Effects of imperfections on the mechanical behavior of a wire-woven bulk Kagome cellular metal under compression

A new cellular metallic structure known as wire-woven bulk Kagome (WBK) has been recently introduced. The fabrication of WBK is done by assembling metal wires in six directions and being brazed at all crossing points. Namely, wires that are naturally easy to handle and have high strength with least defects are used as the raw material to fabricate a structure similar to the Kagome truss. Its mechanical strength and energy absorption capability has been shown to be superior to previously developed cellular metals. The effect of imperfections on the performance of WBK, however, has never been explored either numerically or experimentally. In order to investigate the mechanical characteristics of the WBK under compression, a new hierarchical simulation method was proposed in this paper. First, the behavior of the bulk WBK composed of infinite number of cells in perfectly uniform structure was simulated by finite element analysis conducted on a unit cell under periodic boundary conditions. Second, the equivalent moduli of single truss obtained from the finite element analysis were utilized in the network analysis to examine the effects of geometry and material property imperfections. The imperfections introduced in statistical manner were added on perfect WBK lattice structures, and numerical results of the compressive strength and its sensitivity on the defects were compared with experimental results.