Spectral Finite Element Analysis of Sandwich Beams With Passive Constrained Layer Damping1

Abstract

We present a spectral finite element model (SFEM) for sandwich beams with passive constrained layer damping (PCLD) treatments. The viscoelastic core has a complex modulus that varies with frequency. The SFEM is formulated in the frequency domain using dynamic shape functions based on the exact displacement solutions from progressive wave methods, where we implicitly account for the frequency dependent complex modulus of the viscoelastic core. The SFEM results of natural frequencies and frequency response functions are compared to those calculated using conventional finite element (CFEM), where the Golla-Hughes-McTavish method is used to account for the frequency dependent complex modulus of a viscoelastic core. Also experimental data are used to validate both analyses using frequency response functions measured for two cantilevered sandwich beams with PCLD treatments having 50% and 75% coverage of the beam length. SFEM shows improved computational efficiency and accuracy, because many more elements must be incorporated into the CFEM for comparable accuracy.