Structural-acoustic aspects in the modeling of sandwich structures and computation of equivalent elasticity parameters

Small-deflection theory is used along with FE models to compute the equivalent elasticity parameters of sandwich structures. Eigenfrequency and eigenmode analyses, comparing the equivalent 2-D continua with full 3-D models, are utilized to determine how continuous connections and in-vacuo assumptions are influenced as real-world discontinuities and gas- or foam-filled cavities are included. It is found that discrete connections between structural elements reduce stiffnesses and eigenfrequencies of the net structure substantially. The presence of gas or foam in the core cavities is observed to increase the overall damping of the dynamic panel response while also amplifying certain panel resonances.