Characterization of Polymer-metal Foam Hybrids for Use in Vibration Dampening and Isolation

There is an ever-increasing demand for lightweight, multifunctional material having both higher stiffness and higher damping. In many applications, higher damping in isolators can allow for beneficial changes in the natural frequencies of the vibration isolation system without deterioration in performance. Generally, simplex materials with higher damping usually have lower stiffness and vice versa. This trade-off limits the applicability of homogenous materials in such roles. Therefore, a hybrid material consisting of open cell aluminum foam as ‘skeleton’ with polymeric material introduced into the open pores could be designed to better meet these contradictory demands. This study aims to characterize the dynamic and damping properties of the composite of the aluminum foam and polymer. The hybrid material, modeled as a single degree-of-freedom spring-damper system, is loaded under a sinusoidal compressive force using a universal testing machine yielding a measure of the dynamic stiffness and damping coefficient. This paper presents the experimentally measured damping characteristics for both the unaltered foam as well as the various hybrids of polymers and aluminum foams. By modeling the hybrid as parallel springs of the aluminum and polymers, the damping due to the interface between the two materials is quantified and presented.