Modal analysis of the box assembly with removable component in two configurations
To ensure accurate predictions of behavior and life-cycle of components in their real-use environment, it is essential to develop accurate simulation and testing procedures that reflect such an environment. For components on machines that experience a significant dynamic environment (such as airplanes, missiles, and automobiles), creating testing procedures that accurately mimic such a complex and harsh environment is a significant challenge. Often, testing a system by subjecting it to its operating environment is prohibitive due to cost and testing limitations. Thus, the usefulness of bench testing components through a testing procedure that mimics an operating environment is clear. Structural environmental testing is typically performed using a shaker to apply an environment to a component. However, shaker testing is currently limited in its ability to recreate environments because it often involves excitation in only one axis, when the system experiences a six degree of freedom excitation in practice. Additionally, there are many issues in matching boundary conditions in environmental testing. This paper seeks to explore environmental testing on a simple structure called the “Box Assembly with Removable Component” (BARC). Results from modal testing of the structure will investigate the structures mode shapes, damping, and natural frequencies in a free-free configuration and a fixed-base configuration (mounted to a shaker table). This paper will present a comparison of the mode shapes in these two configurations as well as reciprocities from the modal testing to give further insight into the impedance mismatch between these configurations. Additionally, results from uniaxial shaker excitation of the BARC structure in three axes will be presented. Understanding the differences in dynamics between the two configurations gives insight into how the BARC shaker testing can be understood to more accurately reflect an operational environment.