Effect of deformation mechanisms on in-plane wave propagation in periodic cellular materials

Abstract

Cellular solids’ acoustic properties, such as dispersion, direction dependence, and phase velocities, are inherently coupled to the dominant deformation modes in their ligaments. Understanding and exploiting this coupling can improve the design process of applications utilizing cellular solids’ acoustic properties. This work aims to provide insights into this coupling using finite element simulations. In particular, this work investigates the effect of the two main deformation mechanisms observed in cellular materials, i.e. bending and stretching, on the dispersive and direction dependent characteristics of 2D elastic waves traversing them. Two related honeycomb-based lattices are used in this work, namely a bending dominated lattice and a stretching dominated lattice. Results show that asymmetric waves in the bending dominated lattice are more direction dependent and less dispersive than in the stretching dominated lattice, whereas symmetric waves are generally independent of direction and dispersive in both bending and stretching dominated lattices. In addition, results show that phase velocities of symmetric and asymmetric waves scale linearly with relative density in the bending dominated lattice and nonlinearly with relative density in the stretching dominated lattice. Moreover, maximum phase velocities in the stretching dominated lattice are observed to be higher than in the bending dominated lattice.