Polymer-filled honeycombs to achieve a structural material with appreciable damping

Abstract

In this study, lossy polymeric infills are introduced into metallic honeycombs with the goal that the resulting filled honeycombs simultaneously have high stiffness and appreciable loss factor. A finite element analysis is conducted with the honeycomb walls modeled with beam elements and the polymeric infill modeled with shell elements. Soft (10 MPa) and stiffer (100 MPa) fillers are used, and the filled honeycombs are oriented to deform along the x- and y-directions. The article presents a discussion on the cell geometries that yield the highest stiffness and loss factor, for loading in the two principle directions. When the honeycomb is loaded, the Poisson’s contraction of the cell walls in the transverse direction deforms and increases the strain energy in the polymer, to levels significantly greater than that in an isotropic polymer sheet subject to the same global strain. From the results in the study, it was predicted that filled aluminum honeycombs can achieve a Young’s modulus in the range of 2–7 GPa while simultaneously having a loss factor in the range of 5%–10%. Experimental measurement of Young’s modulus of both unfilled and filled honeycombs of different cell geometries and for different loading directions was compared with the finite element predictions. The finite element predictions compared well with the experiments for the unfilled cases and the trends matched for the filled cases.