Special Topics in Structural Dynamics, Volume 6 pp 515-533 | Cite as
Analysis and Dynamic Characterization of a Resonant Plate for Shock Testing
Abstract
Satellite hardware subjected to pyroshock events during launch must pass one or more qualification tests to ensure proper function during operation in space. This research involves the dynamic characterization of a resonant plate that is used to perform qualification tests. The goal is to develop an analytical model that accurately predicts the shock response spectra (SRS) for a variety of configurations of the resonate plate. Experimental shock data is collected to analyze the system’s variability. Experimental modal tests are performed to determine the system’s mode shapes, natural frequencies, and damping. A finite element model is constructed to predict higher frequency mode shapes for use in the analytical model. The modal superposition technique is then employed to solve for acceleration time responses at specific locations on the plate which allow for the calculation of SRS at each point. The paper concludes by discussing multiple case studies that analyze the effects of key parameters on the analytical model’s predicted SRS.
Keywords
Shock testing Modal analysis Shock response spectrum Modal superpositionNomenclature
- SDOF
Single-degree-of-freedom oscillator describes a system with one natural frequency and one mode shape
- MDOF
Multiple-degree-of-freedom (MDOF) system describes a system with more than one natural frequency and mode shape
- FRF
Frequency response function is used to describe the amplitude of response of a structure as a function of the excitation frequency
- SRS
Shock response spectrum (or spectra) is used to describe the amplitude of response of a structure by exciting an array of SDOF oscillators with a prescribed damping with the acceleration time response collected from the structure. Unlike the FRF, the SRS omits phase information and is most applicable for very high amplitude, very high frequency content, transient excitations
- MAC
Modal assurance criteria refers to a metric that describes the congruency of two mode shapes. Two mode shapes which are exact scalar multiples of each other have a MAC value of 1, and two mode shapes that are exactly orthogonal have a MAC value of 0
Notes
Acknowledgements
The team would like to acknowledge the software used during the research: MATLAB, Abaqus and ME’scope. Also, the team would like to thank the Los Alamos Dynamics Summer School, which provided the project and funding for the research. Lastly, the team would like to thank the three mentors Peter Avitabile, Jim Lake, and Chris Stull for their invaluable guidance.
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