Mechanical properties and damage characterizations of 3D double-arrowhead auxetic structure with high-relative-density realized via selective laser melting

Abstract

It is an obstacle to constructing mechanics model for the deformation of the joint region in struts-made metamaterials with high relative densities. In this work, a generalized semi-empirical method is provided by the statistical fitting of numerical solutions for joint correction. The mechanical models of three-dimensional (3D) double-arrowhead honeycomb (DAH) auxetic structure are reconstructed with broad geometrical parameters applicability. Ti–6Al–4V specimens with varied relative densities are fabricated by selective laser melting and subjected to the uniaxial quasi-static compression. Results show that theoretical predictions of effective modulus, Poisson's ratio, critical strength and failure modes are consistent with experimental results. As the relative density increases, the negative Poisson's ratio effect gradually disappears, and the effective modulus and critical strength increase sharply. In most configurations, the structure's initial failure mode is the completely yielding at the root of short struts. Specimens with high relative densities display excellent energy dissipation, which have the maximal specific energy absorption of 17.33 J/g when the relative density is 11.1 %.