VISCOELASTIC CONSTRAINED-LAYER DAMPING - TIME-DOMAIN FINITE ELEMENT MODELING AND EXPERIMENTAL RESULTS

摘要

The dynamic behavior of typical viscoelastic materials is characterized by strong frequency and temperature dependence. A physically-motivated approach to modeling the time-domain dynamic response of viscoelastic structures is reported here. The frequency dependent behavior is captured using the concept of "anelastic displacement fields," (ADF) which is based on a decomposition of the total displacement field into two parts: one elastic, the other anelastic. General coupled constitutive equations for the total and anelastic stresses are developed in terms of the total and anelastic strains, and specialized to isotropic materials in plane stress. The partial differential equations governing the temporal evolution of the total and anelastic displacement fields are developed in a parallel fashion, involving the divergence of appropriate stress tensors. These equations are solved using ADF-based finite elements. The case of a constrained-layer damping treatment is analyzed both experimentally by vibration tests and numerically by the ADF approach. Modal damping ratios and natural frequencies were compared for the first five modes, in a range between 0 and 1500 Hz. Use of a single ADF adequately captures the frequency dependence of the material. Multiple ADFs increase the accuracy of the results.