Improved mechanical properties and energy absorption of Ti6Al4V laser powder bed fusion lattice structures using curving lattice struts

Abstract

A porous lattice structure with highly controllable mechanical properties, low weight, and high strength is the most promising option for many fields, such as the aerospace, automobile, and biomedical industries. However, the most common and critical issue is the excessively high stress concentration at the struts’ nodes when the lattice structure is loaded. Thus, a curving lattice design strategy is proposed, maintaining a light structure, through which either a circular or elliptical arc is used in the lattice struts to obtain new forms of curving lattice structures. By establishing theoretical models and preparing samples by laser powder bed fusion (L-PBF), combined with scanning electron microscopy (SEM), quasi-static uniaxial compressive experiments, finite element analysis (FEA), and Gibson-Ashby models, excellent results were obtained. The stress distribution of the original under the loads was altered in the curving lattice structure and the stress concentration at the nodes of the struts was effectively relieved, dramatically improving its mechanical properties. Compared with the original structure, the specific elastic modulus and specific compressive strength of curving lattice structures were maximally increased by 213.7% and 126.2%, respectively. Meanwhile, the curving lattice structure had a superior energy absorption capacity, with a significant increase of 92.9%.