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Ken Gall

Professor in the Thomas Lord Department of Mechanical Engineering and Materials Science
Thomas Lord Department of Mechanical Engineering and Materials Science
144 Hudson Hall, Box 90300, Durham, NC 27708
144 Hudson Hall, Box 90300, Durham, NC 27708

Selected Publications


A bending model for assessing relative stiffness and strength of orthopaedic fixation constructs.

Journal Article Clin Biomech (Bristol, Avon) · January 2024 BACKGROUND: The purpose of this study is to develop a simple and reproducible bending model that is compatible with a wide range of orthopaedic fixation devices and 3D printed spacers. METHODS: A robust 4-point bending model was constructed by securing saw ... Full text Link to item Cite

Printability and mechanical behavior as a function of base material, structure, and a wide range of porosities for polymer lattice structures fabricated by vat-based 3D printing

Journal Article Additive Manufacturing · September 25, 2023 Lattice structures offer desirable functionality for engineering design such as having a high strength-to-weight ratio and efficient heat exchange. Lattice parameters can be adjusted to achieve specific benchmarks such as porosity, surface area, weight, or ... Full text Cite

Novel 3D printed lattice structure titanium cages evaluated in an ovine model of interbody fusion.

Journal Article JOR spine · September 2023 BackgroundThe use of intervertebral cages within the interbody fusion setting is ubiquitous. Synthetic cages are predominantly manufactured using materials such as Ti and PEEK. With the advent of additive manufacturing techniques, it is now possib ... Full text Cite

Prediction of tensile performance for 3D printed photopolymer gyroid lattices using structural porosity, base material properties, and machine learning

Journal Article Materials and Design · August 1, 2023 Advancements in additive manufacturing (AM) technology and three-dimensional (3D) modeling software have enabled the fabrication of parts with combinations of properties that were impossible to achieve with traditional manufacturing techniques. Porous desi ... Full text Cite

Tensile performance data of 3D printed photopolymer gyroid lattices.

Journal Article Data in brief · August 2023 Additive manufacturing has provided the ability to manufacture complex structures using a wide variety of materials and geometries. Structures such as triply periodic minimal surface (TPMS) lattices have been incorporated into products across many fields d ... Full text Cite

Deformation and Durability of Soft 3D-printed Polycarbonate Urethane Porous Membranes for Potential Use in Pelvic Organ Prolapse.

Journal Article Journal of biomechanical engineering · May 2023 Pelvic organ prolapse (POP) is the herniation of the pelvic organs into the vaginal space, resulting in the feeling of a bulge and organ dysfunction. Treatment of POP often involves repositioning of the organs using a polypropylene mesh, which has recently ... Full text Cite

Effect of stress state on the mechanical behavior of 3D printed porous Ti6Al4V scaffolds produced by laser powder bed fusion

Journal Article Materials Science and Engineering: B · December 1, 2022 Metallic lattice structures have interconnected porosity for promoting osseointegration and stiffness comparable to bone ideal for minimizing stress shielding. These benefits have caused a widespread proliferation of porous metal scaffolds in orthopedic im ... Full text Cite

Interface contact behavior of 3D printed porous surfaces

Journal Article Journal of Materials Research and Technology · November 1, 2022 When a 3D printed implant integrates a thin surface lattice, the geometry of this porous region controls the bone-implant interface, affecting both short-term implant stability and long-term osseointegration. In intervertebral devices, for example, high ex ... Full text Cite

Flaw sensitivity and tensile fatigue of a high-strength hydrogel

Journal Article International Journal of Fatigue · October 1, 2022 This work describes mechanical behavior of a high-strength hydrogel composite relative to costal cartilage. The materials are analyzed for monotonic ultimate tensile strength (UTS) with differing flaws that represent extreme differences in local stress con ... Full text Cite

A Synthetic Hydrogel Composite with a Strength and Wear Resistance Greater than Cartilage

Journal Article Advanced Functional Materials · October 1, 2022 Key hurdles for replacing damaged cartilage with an equivalent synthetic construct are the development of a hydrogel with a strength that exceeds that of cartilage and fixation of this hydrogel onto the surface of an articulating joint. This article descri ... Full text Cite

Thiol-Based Three-Dimensional Printing of Fully Degradable Poly(propylene fumarate) Star Polymers.

Journal Article ACS applied materials & interfaces · August 2022 Poly(propylene fumarate) star polymers photochemically 3D printed with degradable thiol cross-linkers yielded highly tunable biodegradable polymeric materials. Tailoring the alkene:thiol ratio (5:1, 10:1, 20:1 and 30:1) and thus the cross-link density with ... Full text Cite

High-Strength Composites Based on 3D Printed Porous Scaffolds Infused with a Bioresorbable Mineral–Organic Bone Adhesive

Journal Article Advanced Engineering Materials · July 1, 2022 Bioresorbable bone adhesives are attractive materials for applications where bone repair, regeneration, or reconstruction is involved. They can potentially augment or replace metal fixation while allowing to avoid follow-up procedures upon bone healing. Co ... Full text Cite

Corrosion Resistance of 3D Printed Ti6Al4V Gyroid Lattices with Varying Porosity.

Journal Article Materials (Basel, Switzerland) · July 2022 Corrosion of medical implants is a possible failure mode via induced local inflammatory effects, systemic deposition and corrosion related mechanical failure. Cyclic potentiodynamic polarisation (CPP) testing was utilized to evaluate the effect of increase ... Full text Cite

Eight-Fold Intensification of Electrochemical Azidooxygenation with a Flow-Through Electrode

Journal Article ACS Sustainable Chemistry and Engineering · June 13, 2022 Finding ways to reduce reactor volume while increasing product output for electro-organic reactions would facilitate the broader adoption of such reactions for the production of chemicals in a commercial setting. This work investigates how the use of flow ... Full text Cite

Effects of 3D printed surface topography and normal force on implant expulsion.

Journal Article Journal of the mechanical behavior of biomedical materials · June 2022 3D printing is a critical method for manufacturing metallic implants as it enables direct fabrication of intricate geometries and porous structures inaccessible to other manufacturing methods. Some common 3D printed porous structures are strut based (e.g. ... Full text Cite

Outcomes of Surgical Reconstruction Using Custom 3D-Printed Porous Titanium Implants for Critical-Sized Bone Defects of the Foot and Ankle.

Journal Article Foot Ankle Int · June 2022 BACKGROUND: Treating critically sized defects (CSDs) of bone remains a significant challenge in foot and ankle surgery. Custom 3D-printed implants are being offered to a small but growing subset of patients as a salvage procedure in lieu of traditional alt ... Full text Link to item Cite

From bottle to microplastics: Can we estimate how our plastic products are breaking down?

Journal Article The Science of the total environment · March 2022 Microplastics (MPs) have become an emerging new pollutant of rising concern due to the exponential growth of plastics in consumer products. Most MP and nanoplastic pollution comes from the fragmentation of plastics through mechanical stress, chemical react ... Full text Cite

Direct evidence of interfacial crystallization preventing weld formation during fused filament fabrication of poly(ether ether ketone)

Journal Article Additive Manufacturing · March 1, 2022 Poly(ether ether ketone) (PEEK) is a high-performance, semicrystalline thermoplastic that has attracted significant interest for material extrusion additive manufacturing techniques such as fused filament fabrication (FFF) but remains beset by poor weld st ... Full text Cite

Computational and image processing methods for analysis and automation of anatomical alignment and joint spacing in reconstructive surgery.

Journal Article Int J Comput Assist Radiol Surg · March 2022 PURPOSE: Reconstructive surgeries to treat a number of musculoskeletal conditions, from arthritis to severe trauma, involve implant placement and reconstructive planning components. Anatomically matched 3D-printed implants are becoming increasingly patient ... Full text Link to item Cite

Patient- and Ventilator-Specific Modeling to Drive the Use and Development of 3D Printed Devices for Rapid Ventilator Splitting During the COVID-19 Pandemic

Conference Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) · January 1, 2022 In the early days of the COVID-19 pandemic, there was a pressing need for an expansion of the ventilator capacity in response to the COVID19 pandemic. Reserved for dire situations, ventilator splitting is complex, and has previously been limited to patient ... Full text Cite

A bending model for assessing relative stiffness and strength of orthopaedic fixation constructs.

Journal Article Clin Biomech (Bristol, Avon) · January 2024 BACKGROUND: The purpose of this study is to develop a simple and reproducible bending model that is compatible with a wide range of orthopaedic fixation devices and 3D printed spacers. METHODS: A robust 4-point bending model was constructed by securing saw ... Full text Link to item Cite

Printability and mechanical behavior as a function of base material, structure, and a wide range of porosities for polymer lattice structures fabricated by vat-based 3D printing

Journal Article Additive Manufacturing · September 25, 2023 Lattice structures offer desirable functionality for engineering design such as having a high strength-to-weight ratio and efficient heat exchange. Lattice parameters can be adjusted to achieve specific benchmarks such as porosity, surface area, weight, or ... Full text Cite

Novel 3D printed lattice structure titanium cages evaluated in an ovine model of interbody fusion.

Journal Article JOR spine · September 2023 BackgroundThe use of intervertebral cages within the interbody fusion setting is ubiquitous. Synthetic cages are predominantly manufactured using materials such as Ti and PEEK. With the advent of additive manufacturing techniques, it is now possib ... Full text Cite

Prediction of tensile performance for 3D printed photopolymer gyroid lattices using structural porosity, base material properties, and machine learning

Journal Article Materials and Design · August 1, 2023 Advancements in additive manufacturing (AM) technology and three-dimensional (3D) modeling software have enabled the fabrication of parts with combinations of properties that were impossible to achieve with traditional manufacturing techniques. Porous desi ... Full text Cite

Tensile performance data of 3D printed photopolymer gyroid lattices.

Journal Article Data in brief · August 2023 Additive manufacturing has provided the ability to manufacture complex structures using a wide variety of materials and geometries. Structures such as triply periodic minimal surface (TPMS) lattices have been incorporated into products across many fields d ... Full text Cite

Deformation and Durability of Soft 3D-printed Polycarbonate Urethane Porous Membranes for Potential Use in Pelvic Organ Prolapse.

Journal Article Journal of biomechanical engineering · May 2023 Pelvic organ prolapse (POP) is the herniation of the pelvic organs into the vaginal space, resulting in the feeling of a bulge and organ dysfunction. Treatment of POP often involves repositioning of the organs using a polypropylene mesh, which has recently ... Full text Cite

Effect of stress state on the mechanical behavior of 3D printed porous Ti6Al4V scaffolds produced by laser powder bed fusion

Journal Article Materials Science and Engineering: B · December 1, 2022 Metallic lattice structures have interconnected porosity for promoting osseointegration and stiffness comparable to bone ideal for minimizing stress shielding. These benefits have caused a widespread proliferation of porous metal scaffolds in orthopedic im ... Full text Cite

Interface contact behavior of 3D printed porous surfaces

Journal Article Journal of Materials Research and Technology · November 1, 2022 When a 3D printed implant integrates a thin surface lattice, the geometry of this porous region controls the bone-implant interface, affecting both short-term implant stability and long-term osseointegration. In intervertebral devices, for example, high ex ... Full text Cite

Flaw sensitivity and tensile fatigue of a high-strength hydrogel

Journal Article International Journal of Fatigue · October 1, 2022 This work describes mechanical behavior of a high-strength hydrogel composite relative to costal cartilage. The materials are analyzed for monotonic ultimate tensile strength (UTS) with differing flaws that represent extreme differences in local stress con ... Full text Cite

A Synthetic Hydrogel Composite with a Strength and Wear Resistance Greater than Cartilage

Journal Article Advanced Functional Materials · October 1, 2022 Key hurdles for replacing damaged cartilage with an equivalent synthetic construct are the development of a hydrogel with a strength that exceeds that of cartilage and fixation of this hydrogel onto the surface of an articulating joint. This article descri ... Full text Cite

Thiol-Based Three-Dimensional Printing of Fully Degradable Poly(propylene fumarate) Star Polymers.

Journal Article ACS applied materials & interfaces · August 2022 Poly(propylene fumarate) star polymers photochemically 3D printed with degradable thiol cross-linkers yielded highly tunable biodegradable polymeric materials. Tailoring the alkene:thiol ratio (5:1, 10:1, 20:1 and 30:1) and thus the cross-link density with ... Full text Cite

High-Strength Composites Based on 3D Printed Porous Scaffolds Infused with a Bioresorbable Mineral–Organic Bone Adhesive

Journal Article Advanced Engineering Materials · July 1, 2022 Bioresorbable bone adhesives are attractive materials for applications where bone repair, regeneration, or reconstruction is involved. They can potentially augment or replace metal fixation while allowing to avoid follow-up procedures upon bone healing. Co ... Full text Cite

Corrosion Resistance of 3D Printed Ti6Al4V Gyroid Lattices with Varying Porosity.

Journal Article Materials (Basel, Switzerland) · July 2022 Corrosion of medical implants is a possible failure mode via induced local inflammatory effects, systemic deposition and corrosion related mechanical failure. Cyclic potentiodynamic polarisation (CPP) testing was utilized to evaluate the effect of increase ... Full text Cite

Eight-Fold Intensification of Electrochemical Azidooxygenation with a Flow-Through Electrode

Journal Article ACS Sustainable Chemistry and Engineering · June 13, 2022 Finding ways to reduce reactor volume while increasing product output for electro-organic reactions would facilitate the broader adoption of such reactions for the production of chemicals in a commercial setting. This work investigates how the use of flow ... Full text Cite

Effects of 3D printed surface topography and normal force on implant expulsion.

Journal Article Journal of the mechanical behavior of biomedical materials · June 2022 3D printing is a critical method for manufacturing metallic implants as it enables direct fabrication of intricate geometries and porous structures inaccessible to other manufacturing methods. Some common 3D printed porous structures are strut based (e.g. ... Full text Cite

Outcomes of Surgical Reconstruction Using Custom 3D-Printed Porous Titanium Implants for Critical-Sized Bone Defects of the Foot and Ankle.

Journal Article Foot Ankle Int · June 2022 BACKGROUND: Treating critically sized defects (CSDs) of bone remains a significant challenge in foot and ankle surgery. Custom 3D-printed implants are being offered to a small but growing subset of patients as a salvage procedure in lieu of traditional alt ... Full text Link to item Cite

From bottle to microplastics: Can we estimate how our plastic products are breaking down?

Journal Article The Science of the total environment · March 2022 Microplastics (MPs) have become an emerging new pollutant of rising concern due to the exponential growth of plastics in consumer products. Most MP and nanoplastic pollution comes from the fragmentation of plastics through mechanical stress, chemical react ... Full text Cite

Direct evidence of interfacial crystallization preventing weld formation during fused filament fabrication of poly(ether ether ketone)

Journal Article Additive Manufacturing · March 1, 2022 Poly(ether ether ketone) (PEEK) is a high-performance, semicrystalline thermoplastic that has attracted significant interest for material extrusion additive manufacturing techniques such as fused filament fabrication (FFF) but remains beset by poor weld st ... Full text Cite

Computational and image processing methods for analysis and automation of anatomical alignment and joint spacing in reconstructive surgery.

Journal Article Int J Comput Assist Radiol Surg · March 2022 PURPOSE: Reconstructive surgeries to treat a number of musculoskeletal conditions, from arthritis to severe trauma, involve implant placement and reconstructive planning components. Anatomically matched 3D-printed implants are becoming increasingly patient ... Full text Link to item Cite

Patient- and Ventilator-Specific Modeling to Drive the Use and Development of 3D Printed Devices for Rapid Ventilator Splitting During the COVID-19 Pandemic

Conference Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) · January 1, 2022 In the early days of the COVID-19 pandemic, there was a pressing need for an expansion of the ventilator capacity in response to the COVID19 pandemic. Reserved for dire situations, ventilator splitting is complex, and has previously been limited to patient ... Full text Cite

Stochastic Modeling and identification of material parameters on structures produced by additive manufacturing

Journal Article Computer Methods in Applied Mechanics and Engineering · December 15, 2021 A methodology enabling the representation, sampling, and identification of spatially-dependent stochastic material parameters on complex structures produced by additive manufacturing is presented. The modeling component builds upon earlier works by the aut ... Full text Cite

High-strength, porous additively manufactured implants with optimized mechanical osseointegration.

Journal Article Biomaterials · December 2021 Optimization of porous titanium alloy scaffolds designed for orthopedic implants requires balancing mechanical properties and osseointegrative performance. The tradeoff between scaffold porosity and the stiffness/strength must be optimized towards the goal ... Full text Cite

Poly(lactide-co-ε-caprolactone) scaffold promotes equivalent tissue integration and supports skin grafts compared to a predicate collagen scaffold.

Journal Article Wound Repair Regen · November 2021 Dermal scarring from motor vehicle accidents, severe burns, military blasts, etc. is a major problem affecting over 80 million people worldwide annually, many of whom suffer from debilitating hypertrophic scar contractures. These stiff, shrunken scars limi ... Full text Link to item Cite

Effect of surface topography on in vitro osteoblast function and mechanical performance of 3D printed titanium.

Journal Article J Biomed Mater Res A · October 2021 Critical-sized defects remain a significant challenge in orthopaedics. 3D printed scaffolds are a promising treatment but are still limited due to inconsistent osseous integration. The goal of the study is to understand how changing the surface roughness o ... Full text Open Access Link to item Cite

Fabrication of Biomedical Scaffolds Using Biodegradable Polymers.

Journal Article Chemical reviews · September 2021 Degradable polymers are used widely in tissue engineering and regenerative medicine. Maturing capabilities in additive manufacturing coupled with advances in orthogonal chemical functionalization methodologies have enabled a rapid evolution of defect-speci ... Full text Cite

Structure-property relationships in 3D-printed poly(l-lactide-co-ε-caprolactone) degradable polymer.

Journal Article Journal of the mechanical behavior of biomedical materials · September 2021 The recent growth of polymer 3D-printing has brought innovation to the medical implant field. Implants with complex porous structures can be fabricated by printing to tune mechanical behavior and enable diffusion, consequently improving integration with ti ... Full text Cite

Correction to: Tensile Fatigue of Poly(Vinyl Alcohol) Hydrogels with Bio-Friendly Toughening Agents (Macromolecular Materials and Engineering, (2020), 305, 3, (1900784), 10.1002/mame.201900784)

Journal Article Macromolecular Materials and Engineering · August 1, 2021 In the published version of this article, section 1.2, the sentence “The ratio of the width of the grip section to the width of the gauge section was controlled at 3:1 (ratio described as grip:gauge).” contains an incorrect ratio. The correct sentence shou ... Full text Cite

Rotational Wear and Friction of Ti-6Al-4V and CoCrMo against Polyethylene and Polycarbonate Urethane

Journal Article Biotribology · June 1, 2021 Total joint replacement (TJR) is a successful procedure for millions of patients each year. Optimizing mechanical properties of bearing couples is important to increase implant longevity and improve patient outcomes. Softer viscoelastic materials offer a p ... Full text Open Access Cite

Processing, structure, and properties of additively manufactured titanium scaffolds with gyroid-sheet architecture

Journal Article Additive Manufacturing · May 1, 2021 While the relationships between processing, structure, and properties of solid titanium alloys produced by additive manufacturing have been established, these relationships are less understood for porous materials, particularly those with rough surfaces in ... Full text Cite

Functional repair of critically sized femoral defects treated with bioinspired titanium gyroid-sheet scaffolds.

Journal Article Journal of the mechanical behavior of biomedical materials · April 2021 Despite the innate ability for bone to remodel and repair, its regeneration has a limit. In these cases of critically sized bone defects (CSBD), the bone deficit must be repaired using reconstructive techniques that support immediate load bearing and encou ... Full text Cite

Tailoring nitric oxide release with additive manufacturing to create antimicrobial surfaces.

Journal Article Biomaterials science · April 2021 The current use of implantable and indwelling medical is limited due to potential microbial colonization leading to severe ailments. The aim of this work is to develop bioactive polymers that can be customized based on patient needs and help prevent bacter ... Full text Cite

Compressive anisotropy of sheet and strut based porous Ti-6Al-4V scaffolds.

Journal Article Journal of the mechanical behavior of biomedical materials · March 2021 Porous metallic scaffolds show promise in orthopedic applications due to favorable mechanical and biological properties. In vivo stress conditions on orthopedic implants are complex, often including multiaxial loading across off axis orientations. In this ... Full text Cite

Flaw Sensitivity and Tensile Fatigue of Poly(Vinyl Alcohol) Hydrogels

Journal Article Macromolecular Materials and Engineering · March 1, 2021 Tensile fatigue behavior is commonly overlooked as researchers pursue the toughest hydrogels. This work describes a poly(vinyl alcohol) (PVA) hydrogel prepared through freezing–thawing (FT) processing to achieve varied monotonic strength and toughness. The ... Full text Cite

Evaluation of Host Immune Cellular and Extracellular Matrix Responses to Prolapse Mesh With and Without Tension in a Rat Model.

Journal Article Female pelvic medicine & reconstructive surgery · February 2021 ObjectivesWe sought to determine whether vaginal host immune cellular and extracellular matrix responses are altered in a rat sacrocolpopexy model when lightweight polypropylene mesh is attached on tension versus without tension.MethodsWe ... Full text Cite

High-Strength Hydrogel Attachment through Nanofibrous Reinforcement.

Journal Article Advanced healthcare materials · February 2021 The repair of a cartilage lesion with a hydrogel requires a method for long-term fixation of the hydrogel in the defect site. Attachment of a hydrogel to a base that allows for integration with bone can enable long-term fixation of the hydrogel, but curren ... Full text Cite

Polycarbonate Urethane Mesh: A New Material for Pelvic Reconstruction.

Journal Article Female Pelvic Med Reconstr Surg · February 1, 2021 OBJECTIVE: Polycarbonate urethane (PCU) is a new biomaterial, and its mechanical properties can be tailored to match that of vaginal tissue. We aimed to determine whether vaginal host immune and extracellular matrix responses differ after PCU versus lightw ... Full text Link to item Cite

3D printing of high-strength, porous, elastomeric structures to promote tissue integration of implants.

Journal Article Journal of biomedical materials research. Part A · January 2021 Despite advances in biomaterials research, there is no ideal device for replacing weight-bearing soft tissues like menisci or intervertebral discs due to poor integration with tissues and mechanical property mismatch. Designing an implant with a soft and p ... Full text Cite

Reinforcement and Fatigue of a Bioinspired Mineral-Organic Bioresorbable Bone Adhesive.

Journal Article Advanced healthcare materials · January 2021 Bioresorbable bone adhesives may provide remarkable clinical solutions in areas ranging from fixation and osseointegration of permanent implants to the direct healing and fusion of bones without permanent fixation hardware. Mechanical properties of bone ad ... Full text Cite

The influence of porosity, crystallinity and interlayer adhesion on the tensile strength of 3D printed polylactic acid (PLA)

Journal Article Rapid Prototyping Journal · January 1, 2021 Purpose: The purpose of this study is to understand how printing parameters and subsequent annealing impacts porosity and crystallinity of 3D printed polylactic acid (PLA) and how these structural characteristics impact the printed material’s tensile stren ... Full text Cite

Free boundary effects and representative volume elements in 3D printed Ti-6Al-4V gyroid structures

Journal Article Journal of Materials Research · October 14, 2020 The adoption of selective laser melting (SLM) for fabrication of porous titanium has resulted in many new investigations into the complex design parameters associated with porous architecture of high spatial resolution. The development of meta-materials ha ... Full text Cite

Modulating antibiotic release from reservoirs in 3D-printed orthopedic devices to treat periprosthetic joint infection.

Journal Article J Orthop Res · October 2020 Periprosthetic joint infection is a costly debilitating affliction following total joint arthroplasty. Despite a relatively low incidence rate, periprosthetic joint infection is an increasing problem due to a substantial increase in arthroplasty surgeries ... Full text Link to item Cite

A Synthetic Hydrogel Composite with the Mechanical Behavior and Durability of Cartilage

Journal Article Advanced Functional Materials · September 1, 2020 This article reports the first hydrogel with the strength and modulus of cartilage in both tension and compression, and the first to exhibit cartilage-equivalent tensile fatigue strength at 100 000 cycles. These properties are achieved by infiltrating a ba ... Full text Cite

Pseudoelastic NiTiNOL in Orthopaedic Applications

Journal Article Shape Memory and Superelasticity · September 1, 2020 Pseudoelastic NiTiNOL presents an attractive material option for devices used in clinical orthopaedic applications. The capacity of the material to exert sustained compression during shape recovery aligns well with the mechanobiological factors associated ... Full text Cite

Helmet Modification to PPE With 3D Printing During the COVID-19 Pandemic at Duke University Medical Center: A Novel Technique.

Journal Article The Journal of arthroplasty · July 2020 Care for patients during COVID-19 poses challenges that require the protection of staff with recommendations that health care workers wear at minimum, an N95 mask or equivalent while performing an aerosol-generating procedure with a face shield. The United ... Full text Open Access Cite

Effects of Surface Topography and Chemistry on Polyether-Ether-Ketone (PEEK) and Titanium Osseointegration.

Journal Article Spine · April 2020 Study designAn in vivo study examining the functional osseointegration of smooth, rough, and porous surface topographies presenting polyether-ether-ketone (PEEK) or titanium surface chemistry.ObjectiveTo investigate the effects of surface ... Full text Cite

Tensile Fatigue of Poly(Vinyl Alcohol) Hydrogels with Bio-Friendly Toughening Agents

Journal Article Macromolecular Materials and Engineering · March 1, 2020 Inspired by the avoidance of toxic chemical crosslinkers and harsh reaction conditions, this work describes a poly(vinyl alcohol)-based (PVA) double-network (DN) hydrogel aimed at maintaining biocompatibility through the combined use of bio-friendly additi ... Full text Cite

Authors' reply to Letter to the Editor regarding: Impaction durability of porous PEEK and titanium-coated PEEK interbody fusion devices.

Journal Article The spine journal : official journal of the North American Spine Society · December 2019 Full text Cite

Fatigue behavior of As-built selective laser melted titanium scaffolds with sheet-based gyroid microarchitecture for bone tissue engineering.

Journal Article Acta biomaterialia · August 2019 Selective laser melting (SLM) has enabled the production of porous titanium structures with biological and mechanical properties that mimic bone for orthopedic applications. These porous structures have a reduced effective stiffness which leads to improved ... Full text Cite

Application of a novel suture anchor to abdominal wall closure.

Journal Article Am J Surg · July 2019 BACKGROUND: Mesh suture used in high-tension wound closures produces large knots susceptible to increased palpability, infection, and foreign body response; yet has superior tensile strength and increased resistance to cutting through tissue compared to st ... Full text Link to item Cite

The effect of surface topography and porosity on the tensile fatigue of 3D printed Ti-6Al-4V fabricated by selective laser melting.

Journal Article Materials science & engineering. C, Materials for biological applications · May 2019 Additive manufacturing (3D printing) is emerging as a key manufacturing technique in medical devices. Selective laser melted (SLM) Ti-6Al-4V implants with interconnected porosity have become widespread in orthopedic applications where porous structures enc ... Full text Cite

Examining the viability of carbon fiber reinforced three-dimensionally printed prosthetic feet created by composite filament fabrication.

Journal Article Prosthetics and orthotics international · December 2018 Background:A low-cost, yet high-functioning, fabrication method for prosthetic components is needed to provide underserved amputee communities with quality mobility devices. Three-dimensional printing is a potential alternative, yet limitations in ... Full text Cite

Porous PEEK improves the bone-implant interface compared to plasma-sprayed titanium coating on PEEK.

Journal Article Biomaterials · December 2018 Polyether-ether-ketone (PEEK) is one of the most common materials used for load-bearing orthopaedic devices due to its radiolucency and favorable mechanical properties. However, current smooth-surfaced PEEK implants can lead to fibrous encapsulation and po ... Full text Cite

Bioinspired Mineral-Organic Bioresorbable Bone Adhesive.

Journal Article Advanced healthcare materials · September 2018 Bioresorbable bone adhesives have potential to revolutionize the clinical treatment of the human skeletal system, ranging from the fixation and osteointegration of permanent implants to the direct healing and fusion of bones without permanent fixation hard ... Full text Cite

Creating a small anchor to eliminate large knots in mesh and tape suture

Journal Article Journal of Medical Devices, Transactions of the ASME · September 1, 2018 Wide mesh or tape sutures are used to close high-tension wounds such as in hernia or tendon repair. However, wide sutures produce large knots that are susceptible to increased palpability, infection, and foreign body response. To prevent such adverse event ... Full text Cite

Adjustable-Loop Femoral Cortical Suspensory Fixation for Patellar Tendon Anterior Cruciate Ligament Reconstruction: A Time Zero Biomechanical Comparison With Interference Screw Fixation.

Journal Article The American journal of sports medicine · July 2018 BackgroundAdjustable-loop cortical buttons for femoral fixation of bone-tendon-bone grafts have potential advantages over interference screw fixation; however, these devices have not been benchmarked biomechanically against interference screws. Pu ... Full text Cite

Tough, stable spiroacetal thiol-ene resin for 3D printing

Journal Article Journal of Applied Polymer Science · June 10, 2018 Though over 30 years old, 3D printing has seen an explosion of interest in recent years as technology has become sufficiently advanced and affordable, enabling widespread usage, and investigation of the technique as a method of manufacture. However, the ma ... Full text Cite

Impaction durability of porous polyether-ether-ketone (PEEK) and titanium-coated PEEK interbody fusion devices.

Journal Article The spine journal : official journal of the North American Spine Society · May 2018 Background contextVarious surface modifications, often incorporating roughened or porous surfaces, have recently been introduced to enhance osseointegration of interbody fusion devices. However, these topographical features can be vulnerable to da ... Full text Cite

Modifying hernia mesh design to improve device mechanical performance and promote tension-free repair.

Journal Article J Biomech · April 11, 2018 PURPOSE: Approximately 348,000 ventral hernia repairs are performed annually in the United States and the incisional hernia recurrence rate is approximately 20% as a result of suture and mesh device failure. Device failure is related to changes at the sutu ... Full text Link to item Cite

Design and Structure-Function Characterization of 3D Printed Synthetic Porous Biomaterials for Tissue Engineering.

Journal Article Advanced healthcare materials · April 2018 3D printing is now adopted for use in a variety of industries and functions. In biomedical engineering, 3D printing has prevailed over more traditional manufacturing methods in tissue engineering due to its high degree of control over both macro- and micro ... Full text Cite

Effect of porous orthopaedic implant material and structure on load sharing with simulated bone ingrowth: A finite element analysis comparing titanium and PEEK.

Journal Article Journal of the mechanical behavior of biomedical materials · April 2018 Osseointegration of load-bearing orthopaedic implants, including interbody fusion devices, is critical to long-term biomechanical functionality. Mechanical loads are a key regulator of bone tissue remodeling and maintenance, and stress-shielding due to met ... Full text Cite

Deformation and fatigue of tough 3D printed elastomer scaffolds processed by fused deposition modeling and continuous liquid interface production.

Journal Article Journal of the mechanical behavior of biomedical materials · November 2017 Polyurethane (PU) based elastomers continue to gain popularity in a variety of biomedical applications as compliant implant materials. In parallel, advancements in additive manufacturing continue to provide new opportunities for biomedical applications by ... Full text Cite

Getting PEEK to Stick to Bone: The Development of Porous PEEK for Interbody Fusion Devices.

Conference Techniques in orthopaedics (Rockville, Md.) · September 2017 Interbody fusion cages are routinely implanted during spinal fusion procedures to facilitate arthrodesis of a degenerated or unstable vertebral segment. Current cages are most commonly made from polyether-ether-ketone (PEEK) due to its favorable mechanical ... Full text Cite

Tough Semicrystalline Thiol-Ene Photopolymers Incorporating Spiroacetal Alkenes

Journal Article Macromolecules · June 13, 2017 We report a tough, semicrystalline, ternary thiol-ene polymer system containing linear dithiols, cross-linking trithiols, and spiroacetal alkene units in the main chain backbone that is synthesized by "click" ultraviolet photopolymerization in a one-step, ... Full text Cite

Fatigue of injection molded and 3D printed polycarbonate urethane in solution

Journal Article Polymer · January 13, 2017 Thermoplastic polycarbonate urethanes (PCUs), have promise in many biomedical applications due to their low stiffness, favorable biocompatibility, and high strength. The long-term performance of PCU implants in load-bearing applications remains to be seen, ... Full text Cite

Local deformation behavior of surface porous polyether-ether-ketone.

Journal Article Journal of the mechanical behavior of biomedical materials · January 2017 Surface porous polyether-ether-ketone has the ability to maintain the tensile monotonic and cyclic strength necessary for many load bearing orthopedic applications while providing a surface that facilitates bone ingrowth; however, the relevant deformation ... Full text Cite

Substrate Stiffness Controls Osteoblastic and Chondrocytic Differentiation of Mesenchymal Stem Cells without Exogenous Stimuli.

Journal Article PloS one · January 2017 Stem cell fate has been linked to the mechanical properties of their underlying substrate, affecting mechanoreceptors and ultimately leading to downstream biological response. Studies have used polymers to mimic the stiffness of extracellular matrix as wel ... Full text Cite

Shape-memory Polymers for Orthopaedic Soft-Tissue Repair

Conference Techniques in Orthopaedics · January 1, 2017 Shape-memory polymers (SMPs) and their medical devices offer improved performance for soft-tissue fixation because of their ability to expand in vivo. Here, we describe the basics of the SMP cycle and the fundamental biomechanics of SMP soft-tissue fixatio ... Full text Cite

Development of Novel Orthopaedic Materials

Journal Article Techniques in Orthopaedics · January 1, 2017 Full text Cite

Material Selection

Chapter · January 1, 2017 This chapter highlights the material selection process for shape-memory polymers (SMPs). When selecting SMPs, additional properties need to be considered, so two case studies are given as examples. Current SMPs are grouped based on their polymer structure ... Full text Cite

Change in surface roughness by dynamic shape-memory acrylate networks enhances osteoblast differentiation.

Journal Article Biomaterials · December 2016 Microscale surface roughness has been shown to enhance osseointegration of titanium implants through increased osteoblast differentiation while osteoblast proliferation remains greater on smooth titanium. Taking advantage of these phenomena, we developed a ... Full text Cite

Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?

Journal Article Clinical orthopaedics and related research · November 2016 BackgroundDespite its widespread use in orthopaedic implants such as soft tissue fasteners and spinal intervertebral implants, polyetheretherketone (PEEK) often suffers from poor osseointegration. Introducing porosity can overcome this limitation ... Full text Cite

Dynamic Simulation of the Effects of Graft Fixation Errors During Medial Patellofemoral Ligament Reconstruction

Journal Article Orthopaedic Journal of Sports Medicine · September 12, 2016 Background: Medial patellofemoral ligament (MPFL) reconstruction is performed to prevent recurrent instability, but errors in femoral fixation can elevate graft tension. Hypothesis: Errors related to femoral fixation will overconstrain the patella and incr ... Full text Cite

Use of 3D Printed Bone Plate in Novel Technique to Surgically Correct Hallux Valgus Deformities.

Conference Techniques in orthopaedics (Rockville, Md.) · September 2016 Three-dimensional (3-D) printing offers many potential advantages in designing and manufacturing plating systems for foot and ankle procedures that involve small, geometrically complex bony anatomy. Here, we describe the design and clinical use of a Ti-6Al ... Full text Cite

Impact of surface porosity and topography on the mechanical behavior of high strength biomedical polymers.

Journal Article Journal of the mechanical behavior of biomedical materials · June 2016 The ability to control the surface topography of orthopedic implant materials is desired to improve osseointegration but is often at the expense of mechanical performance in load bearing environments. Here we investigate the effects of surface modification ... Full text Cite

Compressive cyclic ratcheting and fatigue of synthetic, soft biomedical polymers in solution.

Journal Article Journal of the mechanical behavior of biomedical materials · February 2016 The use of soft, synthetic materials for the replacement of soft, load-bearing tissues has been largely unsuccessful due to a lack of materials with sufficient fatigue and wear properties, as well as a lack of fundamental understanding on the relationship ... Full text Cite

A possible oriented attachment growth mechanism for silver nanowire formation

Journal Article Crystal Growth and Design · April 1, 2015 Electron microscopy studies suggest that silver nanowires prepared by an approach reported earlier by us (Caswell, K. K., Bender, C. M., Murphy, C. J. Nano Lett., 2003, 3, 667-669) form through a coarsening process via an oriented attachment mechanism. Ini ... Full text Cite

High-strength, surface-porous polyether-ether-ketone for load-bearing orthopedic implants.

Journal Article Acta biomaterialia · February 2015 Despite its widespread clinical use in load-bearing orthopedic implants, polyether-ether-ketone (PEEK) is often associated with poor osseointegration. In this study, a surface-porous PEEK material (PEEK-SP) was created using a melt extrusion technique. The ... Full text Cite

Environmental security of the European cross-border energy supply infrastructure

Journal Article Environmental Security of the European Cross-Border Energy Supply Infrastructure · January 1, 2015 The current volume provides examples of how environmental hazards such as landslides, earthquakes, mountain processes, cold climate processes and tidal flows and currents can affect the energy supply infrastructure. In times of uncertainty, the security of ... Full text Cite

3D printing of thermoplastic polyurethane shape memory polymer

Conference CAMX 2015 - Composites and Advanced Materials Expo · January 1, 2015 Copyright 2015 by Raytheon Company. Published by CAMX-The Composites and Advanced Materials Expo with permission.Raytheon has developed a thermoplastic polyurethane (TPU) shape memory polymer (SMP) suitable for 3D printing via fused deposition modeling (FD ... Cite

3D printing of thermoplastic polyurethane shape memory polymer

Conference CAMX 2015 - Composites and Advanced Materials Expo · January 1, 2015 Raytheon has developed a thermoplastic polyurethane (TPU) shape memory polymer (SMP) suitable for 3D printing via fused deposition modeling (FDM®). After printing, the final part may be warmed above its glass transition temperature (Tg), packaged into a te ... Cite

Semi-degradable poly(β-amino ester) networks with temporally controlled enhancement of mechanical properties.

Journal Article Acta biomaterialia · August 2014 Biodegradable polymers are clinically used in numerous biomedical applications, and classically show a loss of mechanical properties within weeks of implantation. This work demonstrates a new class of semi-degradable polymers that show an increase in mecha ... Full text Cite

Structural transformations in NiTi shape memory alloy nanowires

Journal Article Journal of Applied Physics · May 21, 2014 Martensitic phase transformation in bulk Nickle-Titanium (NiTi) - the most widely used shape memory alloy - has been extensively studied in the past. However, the structures and properties of nanostructured NiTi remain poorly understood. Here, we perform m ... Full text Cite

A surface stacking fault energy approach to predicting defect nucleation in surface-dominated nanostructures

Journal Article Journal of the Mechanics and Physics of Solids · September 1, 2013 We present a surface stacking fault (SSF) energy approach to predicting defect nucleation from the surfaces of surface-dominated nanostructure such as FCC metal nanowires. The approach leads to a criterion that predicts the initial yield mechanism via eith ... Full text Cite

A micromechanical analysis of the coupled thermomechanical superelastic response of textured and untextured polycrystalline NiTi shape memory alloys

Journal Article Acta Materialia · July 1, 2013 In this paper a micromechanical model that incorporates single crystal constitutive relationships is used for studying the pseudoelastic response of polycrystalline shape memory alloys (SMAs). In the micromechanical framework, the stress-free transformatio ... Full text Cite

On superelastic bending of shape memory alloy beams

Journal Article International Journal of Solids and Structures · May 15, 2013 Abstract In this paper, a closed-form solution is presented for bending analysis of shape memory alloy (SMA) beams. Two different transformation functions are considered: a J2-based model with symmetric tension-compression response, and a J2-I1-based model ... Full text Cite

Photopatterning of thiol-ene-acrylate copolymers

Journal Article Journal of Microelectromechanical Systems · January 1, 2013 Thiol-ene-acrylate copolymers exhibit a unique blend of characteristics which make them suitable for both photolithographic patterning and material property tuning. Five thiol-ene-acrylate monomer blends are found to exhibit similar reaction rates via phot ... Full text Cite

Mechanical requirements of shape-memory polymers in biomedical devices

Journal Article Polymer Reviews · January 1, 2013 Shape-Memory polymers are emerging from the academic laboratory into the clinical field, providing new functionality to often static biomedical implants. The purpose of this review is to discuss why their mechanical properties, particularly toughness, must ... Full text Cite

Active Materials

Chapter · January 1, 2013 Active materials represent a class of materials that are able to undergo a physical or chemical change upon exposure to a stimulus. ey can be activated by temperature, force, electric current, water, and/or chemical moieties. In their “active” form, these ... Full text Cite

Anterior cruciate ligament fixation: is radial force a predictor of the pullout strength of soft-tissue interference devices?

Journal Article The Knee · December 2012 BackgroundIn anterior cruciate ligament (ACL) reconstruction, an interference device achieves soft-tissue graft fixation by radially compressing the graft against the bone.PurposeThe objective of this study was to measure the radial force ... Full text Cite

Bending analysis of textured polycrystalline shape memory alloy beams

Conference ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2012 · December 1, 2012 In this paper a micro-mechanical model that incorporates single crystal constitutive relationships is used for studying the pseudoelastic response of polycrystalline shape memory alloy beams subjected to bending. In the micro-mechanical framework, the stre ... Full text Cite

Atomistic characterization of pseudoelasticity and shape memory in NiTi nanopillars

Journal Article Acta Materialia · October 1, 2012 Molecular dynamics simulations are performed to study the atomistic mechanisms governing the pseudoelasticity and shape memory in nickel-titanium (NiTi) nanostructures. For a 〈1 1 0〉 - oriented nanopillar subjected to compressive loading-unloading, we obse ... Full text Cite

Effect of crosslinking and long-term storage on the shape-memory behavior of (meth)acrylate-based shape-memory polymers

Journal Article Soft Matter · July 28, 2012 This work highlights the free- and fixed-strain shape-memory response of amorphous (meth)acrylate-based shape-memory polymers as the level of crosslinking is varied from uncrosslinked to highly crosslinked (corresponding to a decrease in failure strains an ... Full text Cite

MEMS-Based Nanomechanics: Influence of MEMS Design on Test Temperature

Journal Article Experimental Mechanics · July 1, 2012 Microelectromechanical system (MEMS) devices based on electro-thermal actuation have been used over the past few years to perform tensile tests on nanomaterials. However, previous MEMS designs only allowed small (e. g., <100 nm) total displacement range wi ... Full text Cite

A closed-form solution for superelastic shape memory alloy beams subjected to bending

Conference Proceedings of SPIE - The International Society for Optical Engineering · June 6, 2012 A macroscopic phenomenological framework is used for developing a closed-form solution for analyzing the pure bending of shape memory alloy (SMA) beams. In order to study the effect of tension-compression asymmetry on the bending response, two different tr ... Full text Cite

Coupled thermo-mechanical analysis of shape memory alloy circular bars in pure torsion

Journal Article International Journal of Non-Linear Mechanics · April 1, 2012 Pure torsion of shape memory alloy (SMA) bars with circular cross section is studied by considering the effect of temperature gradient in the cross sections as a result of latent heat generation and absorption during forward and reverse phase transformatio ... Full text Cite

Impact of shape-memory programming on mechanically-driven recovery in polymers

Journal Article Polymer · September 29, 2011 Shape-memory polymers (SMPs) are a class of mechanically functional "smart" materials defined by their ability to change shape upon exposure to an environmental stimulus. The shape-memory effect has traditionally been activated by thermal mechanisms via he ... Full text Cite

Thermo-Mechanical Properties of Semi-Degradable Poly(β-amino ester)-co-Methyl Methacrylate Networks under Simulated Physiological Conditions.

Journal Article Polymer · September 2011 Poly(β-amino ester) networks are being explored for biomedical applications, but they may lack the mechanical properties necessary for long term implantation. The objective of this study is to evaluate the effect of adding methyl methacrylate on networks' ... Full text Cite

Atomistic study of nanotwins in NiTi shape memory alloys

Journal Article Journal of Applied Physics · August 1, 2011 Atomistic simulations are performed to study the structure and geometrical limit of nanoscale twins in NiTi shape memory alloys. We analyze compound twins as narrow as ∼1 nm, involving a few atomic layers. A novel nanotwinned structure is found, forming th ... Full text Cite

Post-Polymerization Crosslinked Polyurethane Shape-Memory Polymers.

Journal Article Journal of applied polymer science · July 2011 Novel urethane shape-memory polymers (SMPs) of significant industrial relevance have been synthesized and characterized. Chemically crosslinked SMPs have traditionally been made in a one-step polymerization of monomers and crosslinking agents. However, the ... Full text Cite

Pseudoelastic intramedullary nailing for tibio-talo-calcaneal arthrodesis.

Journal Article Expert review of medical devices · March 2011 Tibio-talo-calcaneal (TTC) arthrodesis is a procedure to treat severe ankle arthropathy by providing a pain-free and stable fusion. Intramedullary (IM) nails offer a method of internal fixation for TTC arthrodesis by providing compressive stability, as wel ... Full text Cite

Tough shape-memory polymer-fiber composites

Journal Article Journal of Reinforced Plastics and Composites · March 1, 2011 This study describes a multi-faceted materials selection problem that ultimately produces a new class of polymer-fiber composites with failure strains of near 400% and ultimate tensile strengths (UTS's) up to 20 MPa. Independent control of the rubbery modu ... Full text Cite

Effect of poly(ethylene glycol) diacrylate concentration on network properties and in vivo response of poly(β-amino ester) networks.

Journal Article Journal of biomedical materials research. Part A · February 2011 Poly(β-amino ester) networks have shown promise as tissue scaffolds. The objective of this work was to examine the effect of changing poly(ethylene glycol) diacrylate concentration on poly(β-amino ester) network properties and to assess the degradable poly ... Full text Cite

Long-term toughness of photopolymerizable (meth)acrylate networks in aqueous environments.

Journal Article Acta biomaterialia · February 2011 Photopolymerizable (meth)acrylate networks are potentially advantageous biomaterials due to their ability to be formed in situ, their fast synthesis rates and their tailorable material properties. The objective of this study was to evaluate how immersion t ... Full text Cite

Dependence on diameter and growth direction of apparent strain to failure of Si nanowires

Journal Article Journal of Applied Physics · February 1, 2011 Previous studies of the mechanical properties of Si nanowires have not shown the size-dependent strengths that are expected for this prototypical brittle material. A potential source of the ambiguity in the literature is the development of tensile stresses ... Full text Cite

A versatile microelectromechanical system for nanomechanical testing

Journal Article Applied Physics Letters · January 31, 2011 This letter presents a microelectromechanical system (MEMS) material testing setup that relies on electronic measurements of nanospecimen elongation. Compared to previously demonstrated MEMS that rely on high magnification images to measure elongation, thi ... Full text Cite

The influence of trabecular microstructure on mechanical properties and the pullout strength of suture anchors

Conference ASME 2010 Summer Bioengineering Conference, SBC 2010 · December 1, 2010 Full text Cite

A metallization and bonding approach for high performance carbon nanotube thermal interface materials.

Journal Article Nanotechnology · November 2010 A method has been developed to create vertically aligned carbon nanotube (VACNT) thermal interface materials that can be attached to a variety of metallized surfaces. VACNT films were grown on Si substrates using standard CVD processing followed by metalli ... Full text Cite

Shape-memory polymers for biomedical applications

Journal Article Advances in Polymer Science · October 8, 2010 Shape-memory polymers (SMPs) are a class of mechanically functional "smart" materials that have generated substantial interest for biomedical applications. SMPs offer the ability to promote minimally invasive surgery, provide structural support, exert stab ... Full text Cite

The dependence of MG63 osteoblast responses to (meth)acrylate-based networks on chemical structure and stiffness.

Journal Article Biomaterials · August 2010 The cell response to an implant is regulated by the implant's surface properties including topography and chemistry, but less is known about how the mechanical properties affect cell behavior. The objective of this study was to evaluate how the surface sti ... Full text Cite

The effect of the trabecular microstructure on the pullout strength of suture anchors.

Journal Article Journal of biomechanics · July 2010 This study investigates how the microstructural properties of trabecular bone affect suture anchor performance. Seven fresh-frozen humeri were tested for pullout strength with a 5mm Arthrex Corkscrew in the greater tuberosity, lesser tuberosity, and humera ... Full text Cite

Letter to the editor [4]

Journal Article Foot and Ankle International · May 1, 2010 Full text Cite

Pullout strength of suture anchors: effect of mechanical properties of trabecular bone.

Journal Article Journal of biomechanics · April 2010 This study investigated the relationships between trabecular microstructure and elastic modulus, compressive strength, and suture anchor pullout strength. Twelve fresh-frozen humeri underwent mechanical testing followed by micro-computed tomography (microC ... Full text Cite

Cyclic compression behavior of epoxy shape memory polymer foam

Journal Article Mechanics of Materials · April 1, 2010 Shape memory polymer foams have significant potential in aerospace and biomedical applications, however their thermomechanical behavior and damage response under cyclic deformation are not well understood. This paper investigates effects of pre-strain and ... Full text Cite

Effects of sensitizer length on radiation crosslinked shape-memory polymers

Journal Article Radiation Physics and Chemistry · April 1, 2010 Shape-memory polymers (SMPs) are smart materials that can be designed to retain a metastable state and upon activation, recover a preprogrammed shape. In this study, poly(methyl acrylate) (PMA) is blended with poly(ethylene glycol) diacrylate (PEGDA) of va ... Full text Cite

Deformation of epoxy shape memory polymer foam. Part I: Experiments and macroscale constitutive modeling

Journal Article Mechanics of Materials · March 1, 2010 Shape memory polymer foams have both shape memory properties and attributes of low density and compressibility of foams. Potential applications for these materials span from embolic sponges for biomedical uses to morphing wings on advanced airframes. This ... Full text Cite

Deformation of epoxy shape memory polymer foam: Part II. Mesoscale modeling and simulation

Journal Article Mechanics of Materials · March 1, 2010 The present study focuses on how the relative density of an epoxy shape memory polymer foam affects mesostructural response to deformation. The modeled foam had relative densities of 20%, 30%, and 40%, with a glass transition temperature (Tg) near 85 °C as ... Full text Cite

Synthesis, characterization, and cyclic stress-influenced degradation of a poly(ethylene glycol)-based poly(beta-amino ester).

Journal Article Journal of biomedical materials research. Part A · February 2010 This study aims to fundamentally understand the polymer network formed by poly(ethylene glycol) diacrylate (PEGDA) MW 700 and 3-methoxypropylamine (3MOPA) as well as to characterize the degradation response of this material with and without applied cyclic ... Full text Cite

Microstructural inclusion influence on fatigue of a cast A356 aluminum alloy

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · February 1, 2010 We examine the dependence of fatigue properties on the different size scale microstructural inclusions of a cast A356 aluminum alloy in order to quantify the structure-property relations. Scanning electron microscopy (SEM) analysis was performed on fatigue ... Full text Cite

High-strain shape-memory polymers

Journal Article Advanced Functional Materials · January 8, 2010 Shape-memory polymers (SMPs) are self-adjusting, smart materials in which shape changes can be accurately controlled at specific, tailored temperatures. In this study, the glass transition temperature (Tg) is adjusted between 28 and 55°C through synthesis ... Full text Cite

Compression forces of internal and external ankle fixation devices with simulated bone resorption.

Journal Article Foot & ankle international · January 2010 BackgroundInternal and external fixation techniques have been developed to provide rigidity and stability to a fusion site such as in tibiotalocalcaneal (TTC) arthrodesis. Compression of the fusion site plays an integral role in primary bone heali ... Full text Cite

Radiation crosslinked shape-memory polymers

Journal Article Polymer · January 1, 2010 Shape-memory polymers (SMPs) are active smart materials with tunable stiffness changes at specific, tailored temperatures. The use of thermoset SMPs has been limited in commodity applications because a variety of common low-cost plastics processing techniq ... Full text Cite

The effect of chemistry on the polymerization, thermo-mechanical properties and degradation rate of poly(β-amino ester) networks

Journal Article Polymer · January 1, 2010 Poly(β-amino ester) networks are gaining attention as a scaffold material for tissue engineering applications where it is important to have tailorable degradation rate and elastic modulus. The objective of this work is to characterize and understand the re ... Full text Cite

The effect of trabecular microstructure and mechanical properties on the pullout strength of suture anchors

Conference Proceedings of the ASME Summer Bioengineering Conference 2009, SBC2009 · December 1, 2009 Full text Cite

On the toughness of photopolymerizable (meth)acrylate networks for biomedical applications

Journal Article Journal of Applied Polymer Science · December 1, 2009 Photopolymerizable networks are being explored for a variety of biomedical applications because they can be formed in situ, rendering them useful in minimally invasive procedures. The purpose of this study was to establish fundamental relationships between ... Full text Cite

Effect of sidegroup on mechanical properties of acrylate networks for biomedical applications

Conference Proceedings of the ASME Summer Bioengineering Conference, SBC2008 · December 1, 2009 Cite

Preface

Journal Article Materials Research Society Symposium Proceedings · December 1, 2009 Cite

Remote activation of nanomagnetite reinforced shape memory polymer foam

Journal Article Smart Materials and Structures · November 9, 2009 Shape memory polymer foams are thermally activated using remote induction of magnetic susceptor filler particles dispersed in the thermoset foam matrix. Material properties and foam performance are characterized and compared over a range of fillers, induct ... Full text Cite

Synthesis and Thermomechanical Behavior of (Qua)ternary Thiol-ene(/acrylate) Copolymers.

Journal Article Polymer · November 2009 The objective of this work is to characterize and understand the structure-to-thermo-mechanical property relationship in thiol-ene and thiol-ene/acrylate copolymers in order to complement the existing studies on the kinetics of this polymerization reaction ... Full text Cite

The effect of the glass transition temperature on the toughness of photopolymerizable (meth)acrylate networks under physiological conditions.

Journal Article Polymer · October 2009 The purpose of this study is to evaluate how the toughness of photopolymerizable (meth)acrylate networks is influenced by physiological conditions. By utilizing two ternary (meth)acrylate networks, MA-co-MMA-co-PEGDMA and 2HEMA-co-BMA-co-PEGDMA, relationsh ... Full text Cite

Modeling and optimization of the deposition of shape memory Polymers for information storage applications

Journal Article IEEE Transactions on Semiconductor Manufacturing · September 28, 2009 Shape memory polymers are of interest as high-capacity information storage media. This paper seeks to understand the effects of processing conditions on diethylene glycol dimethacrylate (DEGDMA) and bisphenol A ethoxylate dimethacrylate. Full factorial exp ... Full text Cite

Bearing area: a new indication for suture anchor pullout strength?

Journal Article Journal of orthopaedic research : official publication of the Orthopaedic Research Society · August 2009 Studies performed to quantify the pullout strength of suture anchors have not adequately defined the basic device parameters that control monotonic pullout. The bearing area of a suture anchor can be used to understand and predict anchor pullout strength i ... Full text Cite

Shape-memory polymer networks with fe 3O 4 nanoparticles for remote activation

Journal Article Journal of Applied Polymer Science · June 5, 2009 Shape-memory polymers (SMPs) have recently shown the capacity to actuate by remote heating via the incorporation of magnetic nanoparticles into the polymer matrix and exposure to an alternating magnetic field. In this study, methacrylate-based thermoset SM ... Full text Cite

In vivo penetration mechanics and mechanical properties of mouse brain tissue at micrometer scales.

Journal Article IEEE transactions on bio-medical engineering · January 2009 Substantial advancement in the understanding of the neuronal basis of behavior and the treatment of neurological disorders has been achieved via the implantation of various devices into the brain. To design and optimize the next generation of neuronal impl ... Full text Cite

Structure and thermomechanical behavior of NiTiPt shape memory alloy wires.

Journal Article Acta biomaterialia · January 2009 The objective of this work is to understand the structure-property relationships in polycrystalline NiTiPt (Ti 42.7 at.% Ni 7.5 at %Pt) with a composition showing pseudoelasticity at ambient temperatures. Structural characterization of the alloy includes g ... Full text Cite

Effect of chemical crosslinking on the free-strain recovery characteristics of amorphous shape-memory polymers

Conference Materials Research Society Symposium Proceedings · January 1, 2009 The goal of this study is to investigate the fundamental relationship between the extent of crosslinking and shape-memory behavior of amorphous, (meth)acrylate-based polymer networks. The polymer networks were produced by copolymerization of tert-butyl acr ... Full text Cite

Stress-induced martensitic transformations and shape memory at nanometer scales

Conference SMST-2006 - Proceedings of the International Conference on Shape Memory and Superelastic Technologies · December 1, 2008 Nickel-titanium (NiTi) shape memory alloys undergo relatively large recoverable inelastic deformations via a stress-induced martensitic phase transformation. Although stress-induced phase transformations in shape memory alloys are well characterized and ut ... Full text Cite

Tip size effects on atomic force microscopy nanoindentation of a gold single crystal

Journal Article Journal of Applied Physics · December 1, 2008 The effect of tip radius on atomic force microscopy (AFM) nanoindentation is investigated through indentation on the (111) face of a gold single crystal. The hardness is derived using two different methods: by measuring directly the projected area of the r ... Full text Cite

Effect of chemistry on thermo-mechanical shape-memory properties of acrylate networks

Conference Advances in Heterogeneous Material Mechanics 2008 - Proceedings of the 2nd International Conference on Heterogeneous Material Mechanics, ICHMM 2008 · November 28, 2008 Shape-memory acrylate networks are novel materials for both biomedical and industrial applications. The purpose of this study is to understand how the chemical structure dictates thermo-mechanical properties of shape-memory acrylate networks, specifically ... Cite

Cyclic and monotonic behavior of epoxy shape memory polymer foam

Conference Advances in Heterogeneous Material Mechanics 2008 - Proceedings of the 2nd International Conference on Heterogeneous Material Mechanics, ICHMM 2008 · November 28, 2008 Shape memory polymer (SMP) foams have low density, high compressibility, and shape memory properties that give them a wide range of potential applications. However, their thermo-mechanical and structural behavior is not well understood. We investigated epo ... Cite

Structure-property relationships in photopolymerizable polymer networks: Effect of composition on the crosslinked structure and resulting thermomechanical properties of a (meth)acrylate-based system

Journal Article Journal of Applied Polymer Science · November 5, 2008 Photoinitiated polymer networks were formed by copolymerization of terf-butyl acrylate with di(ethylene glycol) dimethacrylate (DEGDMA) or poly(ethylene glycol) dimethacrylate (PEGDMA). The degree of crosslinking was systematically varied by modifying the ... Full text Cite

Stress-induced chemical detection using flexible metal-organic frameworks

Journal Article Journal of the American Chemical Society · November 5, 2008 In this work we demonstrate the concept of stress-induced chemical detection using metal-organic frameworks (MOFs) by integrating a thin film of the MOF HKUST-1 with a microcantilever surface. The results show that the energy of molecular adsorption, which ... Full text Cite

On the elastic modulus of metallic nanowires.

Journal Article Nano letters · November 2008 Previous atomistic simulations and experiments have attributed size effects in the elastic modulus of Ag nanowires to surface energy effects inherent to metallic surfaces. However, differences in experimental and computational trends analyzed here imply th ... Full text Cite

Effect of chemical structure and crosslinking density on the thermo-mechanical properties and toughness of (meth)acrylate shape memory polymer networks

Journal Article Polymer · September 23, 2008 The objective of this work is to characterize and understand structure-mechanical property relationships in (meth)acrylate networks. The networks are synthesized from mono-functional (meth)acrylates with systematically varying sidegroup structure and multi ... Full text Cite

Fracture in single crystal NiTi

Journal Article Journal of the Mechanics and Physics of Solids · September 1, 2008 This paper presents an investigation of the pseudoelastic transformation of two crystallographic orientations of a single crystal NiTi shape memory alloy (SMA). Both uniaxial tension and notched tension samples are considered with the tensile axes along th ... Full text Cite

Thickness and uniformity modeling of the deposition of shape memory polymers for information storage applications

Conference ASMC (Advanced Semiconductor Manufacturing Conference) Proceedings · August 15, 2008 Shape memory polymers are of interest as high-capacity information storage media. This research seeks to understand the effects of processing conditions on the following candidate polymers: diethylene glycol dimethacrylate (DEGDMA), tertbutyl acrylate (tBA ... Full text Cite

Strong, Tailored, Biocompatible Shape-Memory Polymer Networks.

Journal Article Advanced functional materials · August 2008 Shape-memory polymers are a class of smart materials that have recently been used in intelligent biomedical devices and industrial applications for their ability to change shape under a predetermined stimulus. In this study, photopolymerized thermoset shap ... Full text Cite

Effect of microstructure on the fatigue of hot-rolled and cold-drawn NiTi shape memory alloys

Journal Article Materials Science and Engineering: A · July 15, 2008 We present results from a systematic study linking material microstructure to monotonic and fatigue properties of NiTi shape memory alloys. We consider Ni-rich materials that are either (1) hot rolled or (2) hot rolled and cold drawn. In addition to the tw ... Full text Cite

On the relevance of the 8-chain model and the full-network model for the deformation and failure of networks formed through photopolymerization of multifunctional monomers

Journal Article Journal of Polymer Science, Part B: Polymer Physics · June 15, 2008 Crosslinked networks were synthesized by copolymerization of mono-functional tert-butyl acrylate (tBA) with diethyleneglycol dimethacrylate (DEGDMA) or polyethylene glycol dimethacrylates (PEGDMA). By varying the chain length and concentration of the difun ... Full text Cite

Plastic deformation of pentagonal silver nanowires: Comparison between AFM nanoindentation and atomistic simulations

Journal Article Physical Review B - Condensed Matter and Materials Physics · June 13, 2008 The plastic deformation of a pentagonal silver nanowire is studied by nanoindentation using an atomic force microscope (AFM). AFM images of the residual indent reveal the formation of a neck and surface atomic steps. To study the microscopic deformation me ... Full text Cite

Bending and tensile deformation of metallic nanowires

Journal Article Modelling and Simulation in Materials Science and Engineering · June 1, 2008 Using molecular statics simulations and the embedded atom method, a technique for bending silver nanowires and calculating Young's modulus via continuum mechanics has been developed. The measured Young's modulus values extracted from bending simulations we ... Full text Cite

Cytotoxicity and thermomechanical behavior of biomedical shape-memory polymer networks post-sterilization.

Journal Article Biomedical materials (Bristol, England) · March 2008 Shape-memory polymers (SMPs) are being increasingly proposed for use in biomedical devices. This paper investigates the cytotoxicity, surface characteristics and thermomechanics of two acrylate-based SMP networks as a function of sterilization using a mini ... Full text Cite

Thermomechanical formation and recovery of nanoindents in a shape memory polymer studied using a heated tip.

Journal Article Scanning · March 2008 This paper investigates the thermomechanical formation and recovery of nanometer-scale indents in a shape memory polymer (SMP), studied using a heated atomic force microscope (AFM) tip and hot-stage atomic force microscopy. The material tested is a tert-bu ... Full text Cite

Temperature and strain-rate dependence of surface dislocation nucleation.

Journal Article Physical review letters · January 2008 Dislocation nucleation is essential to the plastic deformation of small-volume crystalline solids. The free surface may act as an effective source of dislocations to initiate and sustain plastic flow, in conjunction with bulk sources. Here, we develop an a ... Full text Cite

Deformation limits in shape-memory polymers

Journal Article Advanced Engineering Materials · January 1, 2008 Full text Cite

Understanding, predicting and preventing failure of Ti-Ni shape memory alloys used in medical implants

Chapter · January 1, 2008 In this chapter, the focus is on the mechanical fatigue of shape memory alloys intended for use in biomedical applications. Emphasis is placed on understanding the current state of knowledge regarding processing-structure-property relationships under cycli ... Full text Cite

Thermo-mechanical behavior of epoxy shape memory polymer foams

Journal Article Smart Materials and Structures · December 1, 2007 Shape memory polymer foams have significant potential in biomedical and aerospace applications, but their thermo-mechanical behavior under relevant deformation conditions is not well understood. In this paper we examine the thermo-mechanical behavior of ep ... Full text Cite

Thermal properties of an open cell epoxy shape memory polymer foam

Conference International SAMPE Technical Conference · December 1, 2007 The thermal properties of an epoxy SMF (shape memory polymer foam) are measured and reported for an 18% dense foam, and it was found that the thermal diffusivity increased by an order of magnitude in going from fully expanded to fully compressed, while the ... Cite

Thermo-mechanical behavior of adaptive polymer foam

Conference International SAMPE Technical Conference · December 1, 2007 Adaptive (shape memory) polymer foams have potential aerospace applications, but their thermo-mechanical behavior under deformation conditions is not well understood. We examined epoxy adaptive foams with an average relative density near 20% by deforming t ... Cite

Molecular dynamics simulations of the shape-memory behaviour of polyisoprene

Journal Article Smart Materials and Structures · October 1, 2007 Full-atomistic molecular dynamics simulations are used to study the shape-memory behaviour of a representative amorphous polymer. A virtual polyisoprene was constructed and subjected to uniaxial stretch and hydrostatic compression thermomechanical cycles. ... Full text Cite

Structural engineering with NiTi. II: Mechanical behavior and scaling

Journal Article Journal of Engineering Mechanics · September 1, 2007 This paper continues to address the overarching goal to provide a more unified understanding of NiTi shape memory alloys intended for use in structural applications by attempting to link standard processing practice and basic materials characterization to ... Full text Cite

Structural engineering with NiTi. I: Basic materials characterization

Journal Article Journal of Engineering Mechanics · September 1, 2007 The overarching goal of this two-part paper is to provide a more unified understanding of NiTi shape memory alloys intended for use in structural engineering applications. Here, we present results from basic materials characterization of large diameter pol ... Full text Cite

Characteristics of a commercially available silicon-on-insulator MEMS material

Journal Article Sensors and Actuators, A: Physical · July 20, 2007 Design of microelectromechanical systems (MEMS) requires an understanding of the material characteristics inherent to the specific processing technologies. In this study, several design-critical characteristics of a silicon-on-insulator (SOI) MEMS fabricat ... Full text Cite

Nanoscale indent formation in shape memory polymers using a heated probe tip

Journal Article Nanotechnology · July 18, 2007 This paper presents experimental investigation of nanoscale indentation formation in shape memory polymers. The polymers were synthesized by photopolymerizing a tert-butyl acrylate (tBA) monomer with a poly(ethylene glycol dimethacrylate) (PEGDMA) crosslin ... Full text Cite

A biomechanical comparison of initial fixation strength of 3 different methods of anterior cruciate ligament soft tissue graft tibial fixation: resistance to monotonic and cyclic loading.

Journal Article The American journal of sports medicine · June 2007 BackgroundTibial fixation of soft tissue grafts continues to be problematic in the early postoperative period after anterior cruciate ligament reconstruction.HypothesisNo differences exist for resistance to slippage of soft tissue grafts ... Full text Cite

Nanowires

Journal Article Philosophical Magazine · May 28, 2007 Full text Cite

Nanoindentation of shape memory polymer networks

Journal Article Polymer · May 21, 2007 This work examines the small-scale deformation and thermally induced recovery behavior of shape memory polymer networks as a function of crosslinking structure. Copolymer shape memory materials based on diethylene glycol dimethacrylate and polyethylene gly ... Full text Cite

Galvanic corrosion induced degredation of tensile properties in micromachined polycrystalline silicon

Journal Article Applied Physics Letters · May 17, 2007 Immersion of polycrystalline silicon in hydrofluoric acid-based solutions is often utilized in microsystem fabrication to liberate mechanical structures. The authors demonstrate, using microfabricated tensile specimens, that such etching can cause a catast ... Full text Cite

Unconstrained recovery characterization of shape-memory polymer networks for cardiovascular applications.

Journal Article Biomaterials · May 2007 Shape-memory materials have been proposed in biomedical device design due to their ability to facilitate minimally invasive surgery and recover to a predetermined shape in vivo. Use of the shape-memory effect in polymers is proposed for cardiovascular sten ... Full text Cite

Thermo-mechanical evolution of multilayer thin films: Part I. Mechanical behavior of Au/Cr/Si microcantilevers

Conference Thin Solid Films · February 12, 2007 MEMS microcantilever test structures were utilized to examine the microstructural evolution of Au/Cr/Si thin films subject to annealing. Curvature evolution of the micron-sized structures was measured in response to anneals at various times and temperature ... Full text Cite

Thermo-mechanical evolution of multilayer thin films: Part II. Microstructure evolution in Au/Cr/Si microcantilevers

Conference Thin Solid Films · February 12, 2007 The structure and composition of Au/Cr/Si microcantilevers were examined both before and after annealing. The microstructural observations are used to explain the sophisticated curvature-temperature relationships presented in Part I of this paper series. F ... Full text Cite

Mechanical effects of galvanic corrosion on structural polysilicon

Journal Article Journal of Microelectromechanical Systems · February 1, 2007 The mechanical properties of miniaturized materials depend strongly on their structure, which can be altered by wet chemistry methods common in microsystems postprocessing. In a comprehensive and systematic study, we examine the dissolution of silicon when ... Full text Cite

Deformation of top-down and bottom-up silver nanowires

Journal Article Advanced Functional Materials · January 5, 2007 Atomistic simulations are employed to probe the deformation behavior of experimentally observed top-down and bottom-up face-centered cubic silver nanowires. Stable, 〈110〉 oriented nanowires with a rhombic and truncated-rhombic cross section are considered, ... Full text Cite

Shape memory capacitors for next generation embedded actives

Conference Proceedings - Electronic Components and Technology Conference · December 22, 2006 Integral discrete passives occupy nearly 45% of the board real estate. By embedding passives we have the following advantages: improving packaging efficiency & electrical performance, reducing the use of printed wiring board real estate, eliminating assemb ... Full text Cite

Toward a self-deploying shape memory polymer neuronal electrode.

Journal Article Journal of neural engineering · December 2006 The widespread application of neuronal probes for chronic recording of brain activity and functional stimulation has been slow to develop partially due to long-term biocompatibility problems with existing metallic and ceramic probes and the tissue damage c ... Full text Cite

Incipient yielding behavior during indentation for gold thin films before and after annealing

Journal Article Journal of Materials Research · October 1, 2006 We studied the deformation mechanisms and mechanics during indentation of polycrystalline gold thin films at depths below 100 nm. The measured material hardness decreased from 2.1 ± 0.1 to 1.7 ± 0.1 GPa after annealing for 4 h at 177 °C. Upon closer inspec ... Full text Cite

Deformation of FCC nanowires by twinning and slip

Journal Article Journal of the Mechanics and Physics of Solids · September 1, 2006 We present atomistic simulations of the tensile and compressive loading of single crystal face-centered cubic (FCC) nanowires with 〈 1 0 0 〉 and 〈 1 1 0 〉 orientations to study the propensity of the nanowires to deform via twinning or slip. By studying the ... Full text Cite

Bioabsorbable polymers used in knee arthroscopy, part 1: Basic science and application

Journal Article Techniques in Knee Surgery · September 1, 2006 The use of bioabsorbable materials in orthopedics has increased in the past fifteen years, with technological advances using newer polymers for better fixation. Basic science and clinical research have shown the capacity of bioabsorbable materials to be sa ... Full text Cite

Bioabsorbable polymers used in knee arthroscopy, part 2: Clinical results

Journal Article Techniques in Knee Surgery · September 1, 2006 The use of bioabsorbable materials in orthopedics has increased in the past 15 years, with technological advances using newer polymers for better fixation. Basic science and clinical research have shown the capacity of bioabsorbable materials to be safely ... Full text Cite

The mechanical properties of atomic layer deposited alumina for use in micro- and nano-electromechanical systems

Conference Sensors and Actuators, A: Physical · August 14, 2006 Mechanical characterization of atomic layer deposited (ALD) alumina (Al2O3) for use in micro- and nano-electromechanical systems has been performed using several measurement techniques including: instrumented nanoindentation, bulge testing, pointer rotatio ... Full text Cite

Density functional theory investigation of surface-stress-induced phase transformations in fcc metal nanowires

Journal Article Physical Review B - Condensed Matter and Materials Physics · July 24, 2006 We use density functional theory (DFT) and the tight-binding (TB) method to study the relaxation of narrow Cu, Ni, Au, Pt, and Ag nanowires originally oriented in the 001 direction with a fcc structure. For a small enough diameter (d<2 nm) each nanowire, u ... Full text Cite

Shape memory at nanometer scales

Conference Materials Research Society Symposium Proceedings · May 8, 2006 Nickel-titanium (NiTi) shape memory alloys undergo relatively large recoverable inelastic deformations via a stress-induced martensitic phase transformation. The nanoindentation experimental results presented in this study are the first to show evidence of ... Cite

Galvanic corrosion: A microsystems device integrity and reliability concern

Conference Proceedings of SPIE - The International Society for Optical Engineering · May 3, 2006 We have studied the corrosion of phosphorus-doped polySi when contacted to a gold metallization layer and exposed to various hydrofluoric acid (HF) based chemistries, including mixtures with HCI, C 2H 6O, H 2O, NH 4F, Triton-X-100, as well as vapor-hascd H ... Full text Cite

Stress-induced martensitic transformations and shape memory at nanometer scales

Journal Article Acta Materialia · May 1, 2006 Nickel-titanium (NiTi) shape memory alloys undergo relatively large recoverable inelastic deformations via a stress-induced martensitic phase transformation. Although stress-induced phase transformations in shape memory alloys are well characterized and ut ... Full text Cite

Finite strain 3D thermoviscoelastic constitutive model for shape memory polymers

Journal Article Polymer Engineering and Science · April 1, 2006 A 3D thermoviscoelastic model is proposed to represent the thermomechanical behavior of shape memory polymers. The model is based on a physical understanding of the material behavior and a mechanical interpretation of the stress-strain-temperature changes ... Full text Cite

Atomistic simulations of the yielding of gold nanowires

Journal Article Acta Materialia · February 1, 2006 We performed atomistic simulations to study the effect of free surfaces on the yielding of gold nanowires. Tensile surface stresses on the surfaces of the nanowires cause them to contract along the length with respect to the bulk face-centered cubic lattic ... Full text Cite

Thermomechanics of shape memory polymers: Uniaxial experiments and constitutive modeling

Journal Article International Journal of Plasticity · February 1, 2006 Shape memory polymers (SMPs) can retain a temporary shape after pre-deformation at an elevated temperature and subsequent cooling to a lower temperature. When reheated, the original shape can be recovered. Relatively little work in the literature has addre ... Full text Cite

Instrumented microindentation of nanoporous alumina films

Journal Article Journal of Engineering Materials and Technology · January 1, 2006 We examine the mechanical behavior of anodic alumina thin films with organized nanometer-scale porosity. The cylindrical pores in the alumina film are arranged perpendicular to the film thickness in a near-perfect triangular lattice. The films used in this ... Full text Cite

Use of electrical resistance testing to redefine the transformation kinetics and phase diagram for shape-memory alloys

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 2006 The phase-transformation temperatures of a nickel-titanium-based shape-memory alloy (SMA) were initially evaluated under stress-free conditions by the differential scanning calorimetric (DSC) technique. Results show that the phase-transformation temperatur ... Full text Cite

Shape memory and pseudoelasticity in metal nanowires.

Journal Article Physical review letters · December 2005 Structural reorientations in metallic fcc nanowires are controlled by a combination of size, thermal energy, and the type of defects formed during inelastic deformation. By utilizing atomistic simulations, we show that certain fcc nanowires can exhibit bot ... Full text Cite

Tensile deformation of NiTi wires.

Journal Article Journal of biomedical materials research. Part A · December 2005 We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, a ... Full text Cite

Thermal processing of polycrystalline NiTi shape memory alloys

Conference Medical Device Materials II - Proceedings of the Materials and Processes for Medical Devices Conference 2004 · December 1, 2005 The objective of this study is to examine the effect of heat treatment on polycrystalline Ti-50.9 at.%Ni in hot-rolled and cold-drawn states. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation proces ... Cite

Mechanical effects of galvanic corrosion of thin film polysilicon

Conference American Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS · December 1, 2005 Mechanical, and electrical effects generated by the galvanic corrosion of polysilicon immersed in various hydrofluoric acid (HF)-based solutions are described. Micromachined test structures consisting of phosphorus-doped polysilicon in contact with a gold ... Full text Cite

Improved fracture healing with use of shape memory alloys

Conference Medical Device Materials II - Proceedings of the Materials and Processes for Medical Devices Conference 2004 · December 1, 2005 The introduction of shape memory alloys (SMA) as an active implant material has greatly advanced the medical industry. The most heavily utilized SMA in biomedical applications is nickel titanium (NiTiNOL) due to its ability to instantaneously recover large ... Cite

Optimized thermomechanics of a shape-memory polymer stent to recover at body temperature

Conference Proceedings of the 2005 Summer Bioengineering Conference · December 1, 2005 Cite

Shape-memory polymer based neuronal probes

Conference Proceedings of the 2005 Summer Bioengineering Conference · December 1, 2005 Cite

Elastic Memory Composites (EMC) for deployable industrial and commercial applications

Conference Proceedings of SPIE - The International Society for Optical Engineering · September 29, 2005 The use of smart materials and multifunctional components has the potential to provide enhanced performance, improved economics, and reduced safety concerns for applications ranging from outer space to subterranean. Elastic Memory Composite (EMC) materials ... Full text Cite

Galvanic corrosion of miniaturized polysilicon structures morphological, electrical, and mechanical effects

Journal Article Electrochemical and Solid-State Letters · September 29, 2005 The morphological, electrical, and mechanical effects generated by the galvanic corrosion of polysilicon immersed in a standard aqueous HF solution are described. Micromachined test structures consisting of phosphorus-doped polysilicon in contact with a go ... Full text Cite

Thermal processing of polycrystalline NiTi shape memory alloys

Journal Article Materials Science and Engineering: A · September 25, 2005 The objective of this study is to examine the effect of heat treatment on polycrystalline Ti-50.9 at.% Ni in hot-rolled and cold-drawn states. In particular, we examine microstructure, transformation temperatures as well as mechanical behavior in terms of ... Full text Cite

Shape memory polymers for biomedical applications

Journal Article Advanced Materials and Processes · July 1, 2005 This talk examines the structure, thermo-mechanics, and biomedical applications of shape memory polymers. Shape memory polymers possess the capacity to recover permanent strains on the order of 50 to 400% when subjected to unique thermo-mechanical loading ... Cite

Thermomechanics of the shape memory effect in polymers for biomedical applications.

Journal Article Journal of biomedical materials research. Part A · June 2005 We examine the shape memory effect in polymer networks intended for biomedical, and specifically cardiovascular, applications. The polymers were synthesized by photopolymerization from a tert-butyl acrylate monomer with a diethyleneglycol diacrylate crossl ... Full text Cite

Cast NiTi shape-memory alloys

Journal Article Advanced Engineering Materials · June 1, 2005 The structure and properties of shape memory alloys such as nickel and titanium was studied. Nickel and titanium were melted in a graphite crucible, and the melt was poured in a mild steel cylindrical mold with a wall thickness of 2.54 cm. Single crystals ... Full text Cite

Intrinsic stress development and microstructure evolution of Au/Cr/Si multilayer thin films subject to annealing

Journal Article Scripta Materialia · May 1, 2005 Au/Cr/Si microcantilevers were studied in their as-deposited condition and annealed state, with emphasis on a thermal treatment of 225 °C for 24 h. Change in beam curvature was monitored during isothermal hold as a function of time. Secondary grain growth ... Full text Cite

Environmentally influenced microstructurally small fatigue crack growth in cast magnesium

Journal Article Materials Science and Engineering: A · April 15, 2005 We examine the growth of microstructurally small fatigue cracks in cast AM60B magnesium (Mg) cycled in a water vapor environment. The behavior and growth rates of the small cracks were measured in situ during cycling using a fatigue loading stage contained ... Full text Cite

Shape recovery of nanoscale imprints in a thermoset "shape memory" polymer

Journal Article Applied Physics Letters · March 7, 2005 This letter reports temperature-dependent recovery of atomic force microscope tip-formed indentations in a thermoset shape memory polymer. The indentations are made at both room temperature and 69 °C, and then recovered at temperatures between 40 °C and 70 ... Full text Cite

Tetragonal phase transformation in gold nanowires

Journal Article Journal of Engineering Materials and Technology · January 1, 2005 First principle, tight binding, and semi-empirical embedded atom calculations are used to investigate a tetragonal phase transformation in gold nanowires. As wire diameter is decreased, tight binding and modified embedded atom simulations predict a surface ... Full text Cite

Free recovery effects of shape-memory polymers for cardiovascular stents

Conference Materials Research Society Symposium Proceedings · January 1, 2005 The shape-memory effect was examined in polymer stents intended for cardiovascular applications. Four polymer networks were synthesized from polyethylene glycol) dimethacrylate and tert-butyl acrylate with 10 wt% and 20 wt% crosslinker, and with glass tran ... Full text Cite

The strength of gold nanowires

Journal Article Nano Letters · December 1, 2004 Atomistic simulations are used to investigate the yield strength of experimentally observed atomic and nanometer scale gold wires. The atomistic predictions of strength are quantitatively consistent with discrete experimental measurements and they reveal t ... Full text Cite

Thermomechanics of shape memory polymer nanocomposites

Conference Mechanics of Materials · October 1, 2004 Shape memory polymers (SMPs) have the capacity to recover large strains when pre-deformed at an elevated temperature, cooled to a lower temperature, and reheated. The thermomechanical behavior of SMPs can be tailored by modifying the molecular structure of ... Full text Cite

Yield strength asymmetry in metal nanowires

Journal Article Nano Letters · October 1, 2004 We performed atomistic simulations to study the yield mechanisms in gold nanowires. Perfect fee gold nanowires all yield via the nucleation and propagation of {111}〈112〉 partial dislocations. The magnitude of the yield stress is much larger in tension vers ... Full text Cite

Atomistic simulation of the structure and elastic properties of gold nanowires

Journal Article Journal of the Mechanics and Physics of Solids · September 1, 2004 The atomistic simulations for free surfaces on structure and elastic properties of gold nanowires, were investigated. A static relaxation on the assemblage was also performed. A uniform uniaxial strain was incrementally applied to 1.2% to the relaxed nanow ... Full text Cite

Internal stress storage in shape memory polymer nanocomposites

Journal Article Applied Physics Letters · July 12, 2004 The storage and release of internal stresses in shape memory polymers reinforced with a dispersion of nanometer-scale SiC particles were examined. A quantitative Rietveld analysis of diffraction peaks was used to measure changes in the lattice parameter of ... Full text Cite

Thermomechanical behavior and reliability of AU/SI MEMS structures

Conference Annual Proceedings - Reliability Physics (Symposium) · July 12, 2004 The magnitude and physics of inelastic behavior of Au/Si microelectromechanical structures at various thermomechanical loading conditions were investigated. Bimorph gold and polysilicon cantilever beams were fabricated by commercial foundry process. The cu ... Cite

In-situ studies on short crack growth in cast AM60B magnesium

Journal Article Materialpruefung/Materials Testing · July 1, 2004 In cast AM60B magnesium short cracks were observed to grow at stress intensities below the long crack threshold or even below the effective threshold, respectively. The crack growth behavior was affected by the present microstructure ahead of the crack tip ... Full text Cite

Suppression of inelastic deformation of nanocoated thin film microstructures

Journal Article Journal of Applied Physics · June 15, 2004 A study of the suppression of inelastic deformation in multilayer thin film microstructures by alumina nanocoatings was carried out. It was found that while the 40-nm-thick coating had a small effect on the thermoelastic response of the microstructure, it ... Full text Cite

Shape-memory polymers for microelectromechanical systems

Journal Article Journal of Microelectromechanical Systems · June 1, 2004 This paper investigates the use of shape-memory polymer thin films in microelectromechanical systems (MEMS). Shape-memory polymers possess the capacity to recover large-strain deformations by the application of heat and are candidates for small-scale trans ... Full text Cite

Analysis of the fatigue failure of a mountain bike front shock

Journal Article Engineering Failure Analysis · June 1, 2004 We present an analysis of a mountain bike front shock failure. The failure of the 1-year-old shock occurred catastrophically as the bike was ridden off of a 1-m drop. The failure was the result of fast fracture through both shock tubes at the location wher ... Full text Cite

Creep and stress relaxation in bilayer Au/Si microcantilevers

Conference Proceedings of SPIE - The International Society for Optical Engineering · May 10, 2004 We examine creep of thin film Au on curved bimaterial Au/Si microcantilevers. Time-dependent inelastic strains in the Au film lead to gradual changes in the microcantilever curvature over time. Curvature- temperature-time experiments are used to examine th ... Full text Cite

Creep of thin film Au on bimaterial Au/Si microcantilevers

Journal Article Acta Materialia · May 3, 2004 We examine creep of thin film Au on curved bimaterial Au/Si microcantilevers. Time-dependent inelastic strains in the Au film lead to gradual changes in the microcantilever curvature over time. Curvature- temperature-time experiments are used to examine th ... Full text Cite

Power cycling thermal fatigue of Sn-Pb solder joints on a chip scale package

Journal Article International Journal of Fatigue · May 1, 2004 Tin-Lead (Sn-37wt%Pb) eutectic solder joints on a chip scale package (CSP) attached to a printed circuit board have been tested under power cycling from 0 to 100 °C each cycle. Fatigue failure by near interfacial crack growth was discovered to progress fro ... Full text Cite

Recent advances in fatigue crack growth modeling

Journal Article International Journal of Fracture · April 6, 2004 Recent advances in our understanding of fatigue crack growth processes and respective crack growth modeling techniques are reviewed. Much of the observed experimental behavior (such as the effects of notches, maximum applied stress, crack length, in-plane ... Full text Cite

High cycle fatigue of a die cast AZ91E-T4 magnesium alloy

Journal Article Acta Materialia · March 8, 2004 This study reveals the micro-mechanisms of fatigue crack nucleation and growth in a commercial high-pressure die cast automotive AZ91E-T4 Mg component. Mechanical fatigue tests were conducted under R=-1 conditions on specimens machined at different locatio ... Full text Cite

Surface stress driven reorientation of gold nanowires

Journal Article Physical Review B - Condensed Matter and Materials Physics · January 1, 2004 Atomistic simulations with modified embedded atom method (MEAM), embedded atom method (EAM) and surface embedded atom method (SEAM) potentials reveal that, at certain sizes, a face centered cubic (fcc) gold 〈100〉 nanowire reorients into an fcc 〈110〉 nanowi ... Full text Cite

Thermal cycling response of layered gold/polysilicon MEMS structures

Conference Mechanics of Materials · January 1, 2004 Multi-layer material structures in micro-electromechanical systems (MEMS) differ considerably from their micro-electronic counterparts since the thicknesses of the film and substrate are comparable. Due to thermal expansion coefficient mismatch between met ... Full text Cite

In-situ observations of high cycle fatigue mechanisms in cast AM60B magnesium in vacuum and water vapor environments

Journal Article International Journal of Fatigue · January 1, 2004 We present in situ scanning electron microscopy (SEM) observations regarding the formation and propagation of small fatigue cracks in cast AM60B magnesium. Using an environmental SEM, observations were made in vacuum and in the presence of water vapor at 2 ... Full text Cite

Thermomechanical behavior and reliability of Au/Si MEMS structures

Conference IEEE International Reliability Physics Symposium Proceedings · January 1, 2004 Our work with micromechanical structures investigates the magnitude and physics of inelastic behavior at various thermomechanical-loading conditions. We also seek to achieve greater mechanical stability, for example using nanometer-thick atomic-layer depos ... Full text Cite

Thermomechanics of the shape memory effect in polymers

Conference Materials Research Society Symposium Proceedings · January 1, 2004 Shape memory polymers (SMPs) have the capacity to store and recover relatively large strains when subjected to a unique thermomechanical cycle. In this study, the thermomechanics of strain storage and strain/stress recovery are investigated in a shape memo ... Full text Cite

In-Situ Observations of Low-Cycle Fatigue Damage in Cast AM60B Magnesium in an Environmental Scanning Electron Microscope

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 2004 We present in-situ observations of low-cycle fatigue damage in cast AM60B magnesium. The in-situ fatigue tests were conducted in an environmental scanning electron microscope under both high vacuum and 20 Torr of water vapor. In both environments, fatigue ... Full text Cite

Cast NiTi shape-memory alloys

Conference Materials Research Society Symposium Proceedings · January 1, 2004 The purpose of this study is to investigate the structure and properties of polycrystalline NiTi in its cast form. Although it is commonly stated in the literature that cast NiTi has poor shape-memory behavior, this study demonstrates that with appropriate ... Full text Cite

Optimizing the thermomechanics of shape-memory polymers for biomedical applications

Conference Materials Research Society Symposium Proceedings · January 1, 2004 We examine the shape-memory effect in polymer networks intended for biomedical applications. The polymers were photopolymerized from tert-butyl acrylate (tBA) with polyethyleneglycol dimethacrylate (PEGDMA) acting as a crosslinker. Three-point flexural tes ... Full text Cite

Multiscale structure and properties of cast and deformation processed polycrystalline NiTi shape-memory alloys

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 2004 The objective of this study is to examine fundamental processing-structure-property relationships in polycrystalline NiTi bars. Three different polycrystalline Ti-50.9 at. pct Ni (Ti-55.7 wt pct Ni) materials were examined: (1) cast, (2) cast then hot roll ... Full text Cite

Morphology and microstructure evolution of multilayer Au/Cr/Si thin films subject to annealing

Conference Materials Research Society Symposium Proceedings · January 1, 2004 Au/Cr/Si microcantilevers were studied in their as-deposited condition and annealed state, with emphasis on a thermal treatment of 225 °C for 24 hours. Change in beam curvature was monitored during isothermal hold as a function of time. Secondary grain gro ... Full text Cite

In-situ studies on short crack growth in cast AM60B magnesium

Journal Article Materialpruefung/Materials Testing · January 1, 2004 In cast AM60B magnesium short cracks were observed to grow at stress intensities below the long crack threshold or even below the effective threshold, respectively. The crack growth behavior was affected by the present microstructure ahead of the crack tip ... Full text Cite

Stability and structural transition of gold nanowires under their own surface stresses

Conference Materials Research Society Symposium Proceedings · January 1, 2004 First-principle, tight binding, and semi-empirical embedded atom calculations are used to investigate a tetragonal phase transformation in gold nanowires. As wire diameter is decreased, tight binding and modified embedded atom simulations predict a surface ... Full text Cite

Galvanic cell formation during mems release processes: Implications for sub-micron device fabrication

Conference American Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS · January 1, 2004 The addition of a noble metallization layer to doped polysilicon results in the formation of a galvanic cell when the composite is submerged in aqueous hydrofluoric acid. A corrosion current created by the galvanic cell promotes the electrochemical etching ... Full text Cite

Thermal processing of polycrystalline NiTi shape memory alloys

Conference Materials Research Society Symposium Proceedings · January 1, 2004 The objective of this study is to examine the effect of heat treatment on polycrystalline Ti50.9 at.%Ni subsequent to hot-rolling. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation processed NiTi. T ... Full text Cite

Thermomechanical recovery couplings of shape memory polymers in flexure

Journal Article Smart Materials and Structures · December 1, 2003 Shape memory polymers (SMPs) have the capacity to recover large strains when pre-deformed at an elevated temperature, cooled to a lower temperature and reheated. The thermomechanical recovery behavior of an SMP is examined in three-point flexure for variou ... Full text Cite

Development of a shockless thermally actuated release nut using elastic memory composite material

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 Spacecraft require a variety of separation and release devices to accommodate separation from the launch vehicle and deployment of solar arrays and other appendages. Pyrotechnic release devices produce high shock and contamination, are hazardous and costly ... Cite

Development of a prototype Elastic Memory Composite stem for large space structures

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 This paper describes an engineering program for the development of a seven-meter-long Elastic Memory Composite (EMC), Storable Tubular Extendible Member (STEM) boom, and its deployment-control system. EMC STEM booms have the potential to be much larger, in ... Cite

Shape memory polymers for medical applications

Journal Article Advanced Materials and Processes · December 1, 2003 Shape memory polymers (SMPs) can store and recover large strains by the application of a prescribed thermomechanical cycle. These polymers are drawing significant interest from the medical community. To date, several investigations have been completed to t ... Cite

Fatigue and asymmetric deformation of nitinol shape memory alloys

Conference Medical Device Materials - Proceedings of the Materials and Processes for Medical Devices Conference 2003 · December 1, 2003 Nickel titanium (NiTi) shape memory alloys, also referred to as Nitinol, have been used in various medical applications owing to their ability to recover large stratins and their relatively strong chemical and mechanical bio-compatibility. Amongst other th ... Cite

Shape memory polymers for medical applications

Conference Medical Device Materials - Proceedings of the Materials and Processes for Medical Devices Conference 2003 · December 1, 2003 We present new results on the thermomechanical packaging and recovery behavior of shape memory polymers (SMPs) for medical applications. SMPs possess the ability to store and recover large strains by the application of a prescribed thermomechanical cycle. ... Cite

Surface-stress-induced phase transformation in metal nanowires.

Journal Article Nature materials · October 2003 Several researchers have demonstrated, through experiments and analysis, that the structure and properties of nanometre-scale materials can be quite different to those of bulk materials due to the effect of surfaces. Here we use atomistic simulations to st ... Full text Cite

Shape memory mechanics of an elastic memory composite resin

Journal Article Journal of Intelligent Material Systems and Structures · October 1, 2003 Substantially more attention has been given in the past to shape memory alloys and shape memory ceramics than to shape memory polymers because unreinforced shape memory polymers have much lower stiffness and recovery force potential than shape memory alloy ... Full text Cite

Effect of Al2O3 ALD nanocoatings on the thermo-mechanical behavior of Au/Si MEMS structures

Conference Annual Proceedings - Reliability Physics (Symposium) · July 21, 2003 The effect of Al203 atomic layer deposition (ALD) nanocoatings on the thermo-mechanical behavior of Au/Si microelectromechanical systems (MEMS) structures was discussed. The gold/polysilicon (Au/Si) beam structures were fabricated using the commercially av ... Cite

The shape memory effect and superelasticity in nickel-titanium single crystals aged under applied stress

Conference Journal De Physique. IV : JP · January 1, 2003 Aging under applied stress of <111> and <122> Ti-51at.%Ni single crystals leads to the formation of one crystallographic variant of Ti3Ni4 particles, but after aging without stress four particle variants are observed. It has been shown that the values of s ... Full text Cite

Cyclic plasticity at pores and inclusions in cast Al-Si alloys

Journal Article Engineering Fracture Mechanics · January 1, 2003 Finite element analyses of micronotches including pores and silicon particles of an A356 aluminum alloy were performed to elucidate microstructure-property relations for fatigue crack incubation. Several important findings resulted. By varying the particle ... Full text Cite

Structural evolution during the cycling of NiTi shape memory alloys

Journal Article Zeitschrift fuer Metallkunde/Materials Research and Advanced Techniques · January 1, 2003 The structural evolution in NiTi shape memory alloys subjected to pseudoelastic cycling is examined in the present study. Single crystals with [100] and [111] orientations were subjected to repeated compressive cycles and then studied by transmission elect ... Full text Cite

Microstructure-based fatigue modeling of cast A356-T6 alloy

Journal Article Engineering Fracture Mechanics · January 1, 2003 High cycle fatigue (HCF) life in cast Al-Mg-Si alloys is particularly sensitive to the combination of microstructural inclusions and stress concentrations. Inclusions can range from large-scale shrinkage porosity with a tortuous surface profile to entrappe ... Full text Cite

Detwinning in NiTi alloys

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 2003 This work focuses on the stress-induced transformation in solutionized and overaged single-crystal NiTi alloys. The potential role of detwinning on the recoverable strains was investigated both theoretically and also with temperature-cycling experiments. T ... Full text Cite

Thermomechanical response of bare and Al2O3-nanocoated Au/Si bilayer beams for microelectromechanical systems

Journal Article Journal of Materials Research · January 1, 2003 We present results on the thermomechanical behavior of bare and nanocoated gold/polysilicon (Au/Si) bilayer cantilever beams for microelectromechanical system applications. The cantilever beams have comparable thicknesses of the Au and Si layers and thus e ... Full text Cite

Numerical, experimental, nondestructive, and image analyses of damage progression in cast A356 aluminum notch tensile bars

Journal Article Theoretical and Applied Fracture Mechanics · January 1, 2003 Void nucleation, growth, and coalescence in A356 aluminum notch specimens was determined from a combination of experiments, finite element analysis, nondestructive analysis, and image analysis. Notch Bridgman tension experiments were performed on specimens ... Full text Cite

Development of a shockless thermally actuated release nut using elastic memory composite material

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 Spacecraft require a variety of separation and release devices to accommodate separation from the launch vehicle and deployment of solar arrays and other appendages. Pyrotechnic release devices produce high shock and contamination, are hazardous and costly ... Full text Cite

Making the grade with students: The case for accessibility

Journal Article Journal of Engineering Education · January 1, 2003 Student-based teaching evaluations are one critical component of instructor and course evaluation in most universities. The purpose of this study is to critically examine several factors that drive student-based ratings of instructors and courses in an und ... Full text Cite

Development of a prototype elastic memory composite stem for large space structures

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 This paper describes an engineering program for the development of a seven-meter-long Elastic Memory Composite (EMC), Storable Tubular Extendible Member (STEM) boom, and its deployment-control system. EMC STEM booms have the potential to be much larger, in ... Full text Cite

Thermomechanical response of bare and Al2O3-nanocoated Au/Si bilayer beams for microelectromechanical systems

Journal Article Journal of Materials Research · 2003 We present results on the thermomechanical behavior of bare and nanocoated gold/polysilicon (Au/Si) bilayer cantilever beams for microelectromechanical system applications. The cantilever beams have comparable thicknesses of the Au and Si layers and thus e ... Cite

Effect of Al2O3 ALD nanocoatings on the thermo-mechanical behavior of Au/Si MEMS structures

Conference IEEE International Reliability Physics Symposium Proceedings · January 1, 2003 In the present study we examine the effect of different thermal hold temperatures on creep and stress relaxation during the first thermal cycle and the effect of maximum cycling temperature on thermal ratcheting. We also explore the use of Atomic Layer Dep ... Full text Cite

Shape memory polymer nanocomposites

Journal Article Acta Materialia · December 3, 2002 The paper describes the fabrication and characterization of composites with a shape memory polymer matrix and SiC nanoparticulate reinforcements. Composites based on a SMP matrix are active materials capable of recovering relatively large mechanical strain ... Full text Cite

High cycle fatigue mechanisms in a cast AM60B magnesium alloy

Journal Article Fatigue and Fracture of Engineering Materials and Structures · November 1, 2002 We examine micromechanisms of fatigue crack initiation and growth in a cast AM60B magnesium alloy by relating dendrite cell size and porosity under different strain amplitudes in high cycle fatigue conditions. Fatigue cracks formed at casting pores within ... Full text Cite

Cyclic deformation mechanisms in precipitated NiTi shape memory alloys

Journal Article Acta Materialia · October 28, 2002 Results are presented on the cyclic deformation of single crystal NiTi containing Ti3Ni4 precipitates of various sizes. Mechanical cycling experiments reveal that the cyclic degradation resistance of NiTi is strongly dependent on crystallographic orientati ... Full text Cite

Small crack tip cyclic behavior in dual-phase Al-Si alloys

Conference PROCEEDINGS OF THE 4TH INTERNATIONAL CONFERENCE ON NONLINEAR MECHANICS · January 1, 2002 Link to item Cite

Micro and macro deformation of single crystal NiTi

Journal Article Journal of Engineering Materials and Technology · January 1, 2002 We present experimental results on the instrumented Vickers micro-indentation and compression of solutionized Ni-rich NiTi single crystals. The tests are conducted at room temperature where the solutionized Ti-50.9 at percent Ni material is 18 degrees abov ... Full text Cite

Observations on stress-induced transformations in NITI alloys

Conference IUTAM SYMPOSIUM ON MECHANICS OF MARTENSITIC PHASE TRANSFORMATION IN SOLIDS · January 1, 2002 Link to item Cite

Micro-mechanisms of deformation in fiber reinforced polymer matrix elastic memory composites

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 Polymer matrix Elastic Memory Composite (EMC) materials show great potential for use as ultra-light weight deployable structures for space applications. Critical to acceptance of these materials is the ability to efficiently package these materials for lau ... Cite

On the mechanical behavior of single crystal NiTi shape memory alloys and related polycrystalline phenomenon

Journal Article Materials Science and Engineering: A · October 31, 2001 Room temperature monotonic and cyclic stress-strain curves for single crystal and polycrystalline NiTi shape memory alloys containing Ti3Ni4 precipitates are presented. The tensile and compressive single crystal results illustrate the importance of crystal ... Full text Cite

Shape memory and pseudoelastic behavior of 51.5%Ni-Ti single crystals in solutionized and overaged state

Journal Article Acta Materialia · October 9, 2001 Deformation of nickel rich (51.5%Ni) Ni-Ti single crystals are investigated over a wide range of temperatures (77-440 K) and strain levels in compression as high as 9%. These alloys combine high strength with an unusually wide pseudoelasticity temperature ... Full text Cite

Computational micromechanics analysis of cyclic crack-tip behavior for microstructurally small cracks in dual-phase Al-Si alloys

Journal Article Engineering Fracture Mechanics · September 21, 2001 Cracks were simulated to grow through the Al-rich matrix and around silicon particles. The results showed that as the crack approached the particle, the maximum plastic shear strain range at the crack-tip reduced due to the blockage mechanism proposed by m ... Full text Cite

Instrumented micro-indentation of NiTi shape-memory alloys

Journal Article Acta Materialia · September 20, 2001 We study the instrumented Vickers micro-indentation of single-crystal Ti-50.9 at% Ni shape-memory alloys with systematically varied surface normal orientations ([100], [210], [111] and [221]) and Ti3Ni4 precipitate sizes (0 nm, 10 nm, 50 nm, 100 nm, 300 nm ... Full text Cite

Cyclic deformation behavior of single crystal NiTi

Conference Materials Science and Engineering: A · September 15, 2001 Single crystals of NiTi (with 50.8 at.% Ni) were subjected to cyclic loading conditions at room temperature which is above the Ms (martensite start) temperature of - 30°C. The single crystals exhibited remarkable cyclic hardening under zero to compression ... Full text Cite

Fracture of precipitated NiTi shape memory alloys

Journal Article International Journal of Fracture · May 1, 2001 The fracture mechanisms in single crystal and polycrystalline Ti-50.8at%Ni shape memory alloys containing Ti3Ni4 precipitates are studied using the scanning electron microscope (SEM). Aged materials with three different precipitate sizes (50 nm, 150 nm, an ... Full text Cite

On the driving force for fatique crack formation from inclusion and voids in a cast A356 aluminum alloy

Journal Article International Journal of Fracture · January 1, 2001 Monotonic and cyclic finite element simulations are conducted on linear-elastic inclusions and voids embedded in an elasto-plastic matrix material. The elasto-plastic material is modeled with both kinematic and isotropic hardening laws cast in a hardening ... Full text Cite

Micro-mechanisms of deformation in fiber reinforced polymer matrix elastic memory composites

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 Polymer matrix Elastic Memory Composite (EMC) materials show great potential for use as ultra-light weight deployable structures for space applications. A detailed investigation on the micro-mechanisms of deformation in EMC materials is presented. The resu ... Cite

Developments in elastic memory composite materials for spacecraft deployable structures

Conference IEEE Aerospace Conference Proceedings · January 1, 2001 Near-term and future spacecraft and satellites will require large ultra-lightweight structures and components that must be efficiently packaged for launch and reliably deployed on orbit. A new material technology called Elastic Memory Composite (EMC) mater ... Full text Cite

Micro-mechanisms of deformation in fiber reinforced polymer matrix elastic memory composites

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 Polymer matrix Elastic Memory Composite (EMC) materials show great potential for use as ultra-light weight deployable structures for space applications. Critical to acceptance of these materials is the ability to efficiently package these materials for lau ... Full text Cite

Carbon Fiber Reinforced Shape Memory Polymer Composites

Journal Article Journal of Intelligent Materials Systems and Structures · November 1, 2000 Full text Cite

Carbon fiber reinforced shape memory polymer composites

Journal Article Journal of Intelligent Material Systems and Structures · November 1, 2000 In this paper we present results on the deformation of carbon fiber reinforced shape memory polymer matrix composites for deployable space structure applications. The composites were processed using resin transfer molding or a pre-impregnated (pre-preg) la ... Full text Cite

Compressive response of NiTi single crystals

Journal Article Acta Materialia · August 1, 2000 The deformation of NiTi shape memory single crystals are reported under compression loading for selected crystal orientations and two different Ti3Ni4 precipitate sizes. For the [148] orientation, selected for highest recoverable strains, the peak aging tr ... Full text Cite

Deformation of single crystal hadfield steel by twinning and slip

Journal Article Acta Materialia · April 2, 2000 The stress-strain behavior of Hadfield steel (Fe, 12.34 Mn, 1.03 C, in wt%) single crystals was studied for selected crystallographic orientations ([1̄11], [001] and [1̄23]) under tension and compression. The overall stress-strain response was strongly depen ... Full text Cite

Two-dimensional fluorescence intensity distribution analysis: theory and applications.

Journal Article Biophysical journal · April 2000 A method of sample analysis is presented which is based on fitting a joint distribution of photon count numbers. In experiments, fluorescence from a microscopic volume containing a fluctuating number of molecules is monitored by two detectors, using a conf ... Full text Cite

Influence of modified intermetallics and Si particles on fatigue crack paths in a cast A356 Al alloy

Journal Article Fatigue and Fracture of Engineering Materials and Structures · February 1, 2000 Mechanical fatigue tests were conducted on uniaxial specimens machined from a cast A356-T6 aluminum alloy plate at total strain amplitudes ranging from 0.1 to 0.8% (R = -1). The cast alloy contains strontium-modified silicon particles (vol. fract. to appro ... Full text Cite

NiTi experiments versus modeling: Where do we stand?

Conference Proceedings of SPIE - The International Society for Optical Engineering · January 1, 2000 The next generation of shape memory alloy constitutive models must explicitly or implicitly account for the physics of deformation. Such thermodynamic based micro-mechanical or internal state variable models yield a class of constitutive models with predic ... Cite

Finite element analysis of the stress distributions near damaged Si particle clusters in cast Al-Si alloys

Journal Article Mechanics of Materials · January 1, 2000 The finite element method is used to study the effects of particle cluster morphology on the fracture and debonding of silicon particles embedded in an Al-1%Si matrix subjected to tensile-compressive cyclic loading conditions. Representative of an actual c ... Full text Cite

Integration of basic materials research into the design of cast components by a multi-scale methodology

Conference Journal of Engineering Materials and Technology, Transactions of the ASME · January 1, 2000 We present a formal methodology to integrate basic materials research results into a design procedure for engineering components. Although the methodology is generic, we demonstrate its development and application in designing a cast automotive control arm ... Full text Cite

Atomistic simulations on the tensile debonding of an aluminum-silicon interface

Journal Article Journal of the Mechanics and Physics of Solids · January 1, 2000 In this paper we present Modified Embedded Atom Method (MEAM) simulations of the deformation and fracture characteristics of an incoherent interface between pure FCC aluminum and diamond cubic silicon. As a first approximation, the study only considers the ... Full text Cite

Role of intergranular constraint on the stress-induced martensitic transformation in textured polycrystalline NiTi

Journal Article International journal of plasticity · January 1, 2000 The influences of grain boundaries and relative grain misorientations on stress-induced martensitic transformations in NiTi are studied using unique experiments and finite element modeling. Tensile and compressive mechanical tests reveal that polycrystalli ... Full text Cite

Size scale dependence of deformation in NiTi

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) · January 1, 2000 Full text Cite

Tension-compression asymmetry of the stress-strain response in aged single crystal and polycrystalline NiTi

Journal Article Acta Materialia · March 10, 1999 The purpose of this work is to thoroughly understand tension-compression asymmetry in precipitated NiTi using unique experimental results and micro-mechanical modeling. For the first time, tensile and compressive stress-strain behaviors were established on ... Full text Cite

The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling

Journal Article Journal of Engineering Materials and Technology, Transactions of the ASME · January 1, 1999 Transmission electron microscopy is used to determine the microstructures of a Ti- 50.8 at% Ni alloy given different aging treatments. Two different peak-aging treatments are shown to result in disk shaped semi-coherent Ti3Ni4 precipitates with a diameter ... Full text Cite

The debonding and fracture of Si particles during the fatigue of a cast Al-Si alloy

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 1999 Constant-amplitude high-cycle fatigue tests (σmax = 133 MPa, σmax/σy = 0.55, and R = 0.1) were conducted on cylindrical samples machined from a cast A356-T6 aluminum plate: The fracture surface of the sample with the smallest fatigue-crack nucleating defec ... Full text Cite

The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part II-discussion of experimental results

Journal Article Journal of Engineering Materials and Technology, Transactions of the ASME · January 1, 1999 An experimental study was performed to determine the effect of aging on martensitic transformations in NiTi. Polycrystalline and single crystal NiTi ([100], [110], and [111] orientations) were both considered. Stress-induced transformations inpolycrystalli ... Full text Cite

Role of texture in tension-compression asymmetry in polycrystalline NiTi

Journal Article International journal of plasticity · January 1, 1999 The purpose of the present study is to thoroughly understand the stress-strain behavior of polycrystalline NiTi deformed under tension versus compression. To do this, a micromechanical model is used which incorporates single crystal constitutive relationsh ... Full text Cite

On the deformation mechanisms in single crystal hadfield manganese steels

Journal Article Scripta Materialia · February 13, 1998 Full text Cite

Stress-induced martensitic phase transformations in polycrystalline CuZnAl shape memory alloys under different stress states

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 1998 The effect of different uniaxial and triaxial stress states on the stress-induced martensitic transformation in CuZnAl was investigated. Under uniaxial loading, it was found that the compressive stress level required to macroscopically trigger the transfor ... Full text Cite

Fatigue crack growth - a modeling perspective

Conference Proceedings of the TMS Fall Meeting · December 1, 1997 Modeling of fatigue crack growth processes require calculations of crack tip stress fields, including the influence of premature crack contact and crack opening displacements. Two problems that have been of recent interest to the senior author will be desc ... Cite

A methodology for predicting variability in microstructurally short fatigue crack growth rates

Journal Article Journal of Engineering Materials and Technology, Transactions of the ASME · January 1, 1997 A finite element model, which implements single crystal constitutive relationships, was used to simulate fatigue cracks growing at the microstructural level. Plastic deformation (slip) was allowed along two specified microscopic crystallographic planes. A. ... Full text Cite

Crack closure and microstructurally short fatigue crack growth rates

Conference ADVANCES IN FRACTURE RESEARCH, VOLS 1-6 · January 1, 1997 Link to item Cite

FEM study of fatigue crack closure under double slip

Journal Article Acta Materialia · January 1, 1996 An elastic-plastic finite element analysis of Mode I crack growth and plasticity induced crack closure is presented. The simulation, which models crack tip plasticity using two slip planes, predicts slip patterns experimentally observed in real crystals or ... Full text Cite

Plastic zones and fatigue-crack closure under plane-strain double slip

Journal Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science · January 1, 1996 The results of a systematic investigation involving forward and reversed plastic zones for a growing fatigue crack under plane-strain double-slip conditions are presented. The study focuses on plasticdeformation fields outside the small-scale yielding regi ... Full text Cite

Recent advantages in fatigue crack growth modeling

Journal Article International Journal of Fracture · 1996 Recent advances in our understanding of fatigue crack growth processes and respective crack growth modeling techniques are reviewed. Much of the observed experimental behavior, can be explained based on crack closure concepts. Both Dugdale based models and ... Cite