Investigations of viscoelastic structure behavior using a three-dimensional anelastic displacement field finite element

Space systems, in particular, comprise sensitive electronics and delicate mechanical instruments that need to be protected against harsh vibration and shock loads encountered during launch or landing. High damping viscoelastic materials are commonly used in the design of geometrically complex, shock and vibration isolation components. Since shock transients are characterized by a broad frequency spectrum, and since viscoelastic materials are characterized by frequency-dependent mechanical properties, it is necessary to properly model this behavior over the frequency domain of interest. The Anelastic Displacement Fields (ADF) method is employed herein to model frequency-dependence of material properties within a time-domain finite element framework. A solid, four-node tetrahedron, ADF-based finite element is developed for single and multiple ADF. This particular element is then validated and used for the general purpose of investigating damping in given structures that employ viscoelastic materials. The new three-dimensional finite element may also be used to investigate the potential phase dependence of the Poisson's ratio for such materials. Some model predictions are compared against theory.