Truss waviness effects in cellular lattice structures

Methods have emerged for making metallic lattice structures either by the lay up of collinear wire arrays or by stacking woven textile meshes. The two fabrication routes result in similar lattice topologies: the collinear lattice has straight struts while those in the textile lattice are wavy. Wire waviness in the textile lattice results in a knockdown in both the stiffness and strength compared to the collinear lattice. Analytical estimates and finite element (FE) predictions of the through thickness compressive responses of collinear and textile lattices indicate that the stiffness and strength of lattices oriented to form a diamond structure are specimen aspect ratio dependent. By contrast, the stiffness of the collinear and textile lattices oriented to form a square structure is independent of both specimen aspect ratio and height while the strength depends on the sandwich height. Experimental measurements on specimens fabricated from 304L stainless steel are in good qualitative agreement with the elastic ideally-plastic analytical estimates while FE predictions incorporating the full strain hardening response of the parent material give accurate quantitative predictions of the measurements.