Detailed finite element modal analysis of layered isolators is conducted to gain an improved understanding of three-dimensional effects in compression. Layered isolators exhibit transmissibility 'stop bands', or frequency ranges with very low transmissibility. Comparison between one-dimensional theory based on Floquet analysis and the three-dimensional finite element analysis indicates that stop band frequencies predicted using one-dimensional results can be highly inaccurate. Errors for isolators studied in this investigation were between 17-70%. Experimentally transmissibility measurements are obtained for two different layered isolators. Both isolators exhibit pronounced attenuation within stop band frequencies. Good correlation between three-dimensional finite element analysis and experimental data is obtained. Contrary to earlier one-dimensional analyses, material damping can play a significant role in peak attenuation levels. An efficient one-dimensional analysis of layered isolators is developed. This analysis incorporates table look-up frequency corrections to account for three-dimensional elastic effects. A design optimization methodology is then developed for layered isolators subject to quasi-static stiffness constraints. A simulated annealing algorithm is employed to determine optimal material properties and layer thicknesses.
|Number of pages
|Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
|Published - 2000
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