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Non-Schmid effects and finite wavelength instabilities in single crystal metals

Publication ,  Journal Article
Salahshoor, H; Pal, RK; Rimoli, JJ
Published in: Extreme Mechanics Letters
April 1, 2018

A long standing postulate in crystal plasticity of metals, known as Schmid law, states that yielding commences once the resolved shear stress on a slip plane reaches a critical value. While non-Schmid effects have previously been reported experimentally (mostly in alloys) and in molecular-dynamics simulations, we examine the validity of this assumption through phonon stability analysis. We subject four distinct single crystal metals to a combined shear-hydrostatic deformation and identify the onset of plasticity with the onset of an instability. We find significant shear-normal coupling in single crystal metals, reflecting non-Schmid effects in defect nucleation. Also, it is a widespread assumption in the literature (Liu et al., 2010; Van Vliet et al., 2003) that the instabilities in single crystal metals are of long wavelength. In contrast, we show that short wavelength instabilities are abundant. Our results illustrate the potential pitfalls of relying on the widely used elastic stability analysis for investigating defect nucleation.

Duke Scholars

Published In

Extreme Mechanics Letters

DOI

EISSN

2352-4316

Publication Date

April 1, 2018

Volume

20

Start / End Page

9 / 13

Related Subject Headings

  • 4016 Materials engineering
  • 4007 Control engineering, mechatronics and robotics
 

Citation

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Salahshoor, H., Pal, R. K., & Rimoli, J. J. (2018). Non-Schmid effects and finite wavelength instabilities in single crystal metals. Extreme Mechanics Letters, 20, 9–13. https://doi.org/10.1016/j.eml.2017.12.010
Salahshoor, H., R. K. Pal, and J. J. Rimoli. “Non-Schmid effects and finite wavelength instabilities in single crystal metals.” Extreme Mechanics Letters 20 (April 1, 2018): 9–13. https://doi.org/10.1016/j.eml.2017.12.010.
Salahshoor H, Pal RK, Rimoli JJ. Non-Schmid effects and finite wavelength instabilities in single crystal metals. Extreme Mechanics Letters. 2018 Apr 1;20:9–13.
Salahshoor, H., et al. “Non-Schmid effects and finite wavelength instabilities in single crystal metals.” Extreme Mechanics Letters, vol. 20, Apr. 2018, pp. 9–13. Scopus, doi:10.1016/j.eml.2017.12.010.
Salahshoor H, Pal RK, Rimoli JJ. Non-Schmid effects and finite wavelength instabilities in single crystal metals. Extreme Mechanics Letters. 2018 Apr 1;20:9–13.
Journal cover image

Published In

Extreme Mechanics Letters

DOI

EISSN

2352-4316

Publication Date

April 1, 2018

Volume

20

Start / End Page

9 / 13

Related Subject Headings

  • 4016 Materials engineering
  • 4007 Control engineering, mechatronics and robotics