Design, analysis and optimization of lattice structure for additive manufacturing of aerospace components.

Abstract

Additive Manufacturing (AM) techniques, such as Selective Laser Melting (SLM), have gained significant attention in recent years by providing design freedom to engineers to design and fabricate complex cellular structures with tailored mechanical properties. To balance the strength and weight, 3D lightweight metallic Body-Centered Cubic (BCC) lattice sandwiches were fabricated by selective laser melting with titanium alloy (Ti6AL4V). This study investigates the mechanical responses under compression and three-point bending tests experimentally and numerically. The experimentally measured strengths are very close to the numerical predictions, demonstrating excellent mechanical properties. The numerical modelling may represent the stressstrain load-deflection curves, and the failure mode is the strut buckling initiated from the plastic hinges with high stress levels. This paper also explores the mechanical properties of functionally graded density BCC lattice structures, which results in different performances in mechanical behavior compared to uniform graded density BCC lattice structures. Due to the gradient lattice structure, the average bending load capacity significantly increases from 6000.0 N to 16000.0 N. We indicate that the BCC lattice structure only exhibits a dual failure model comprising buckling and fracture, in contrast to other lattice structures that often offer sole buckling or fracture failure. The buckling failure of the struts near the bottom face sheets always arises first and is followed by the subsequent fracture. The BCC lattice sandwiches offer an opportunity to effectively balance strength and weight as they present lower density than engineering alloys and higher strength than honeycombs, foams and pyramid lattice sandwiches.