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.
