Computational prediction of modal damping ratios in thin-walled structures

•We develop a finite element based computation of modal damping ratios in thin-walled structures.•We use shell elements and appropriate volume integrals for the damping computation.•We verify our shell element formulation using solid element and analytical results.•We demonstrate how stress concentrations, and small appendages acting as tuned absorbers, can increase the damping of a structure.

Modal analysis in finite element packages gives natural frequencies and mode shapes, but not modal damping values. Given a constitutive relation for specific material dissipation, volume integrals of the per cycle dissipation can be used to estimate the modal damping. Here, we adopt a well known power law model for such specific dissipation. We develop a modal damping estimation procedure for thin-walled components using shell elements in a commercial finite element package. We validate our shell element results against both analytical results and a solid elements approach developed elsewhere. Our computational approach allows complex geometries in a study of the effects of shape on damping. Finally, we demonstrate the efficacy of both stress concentrations and small tuned resonant appendages in increasing damping.