Effect of topology on strength and energy absorption of PA12 non-auxetic strut-based lattice structures

Abstract

With the increasing development of additive manufacturing (AM) technology, lattice structure (LS) emerged and expanded as a subset of cellular materials. LSs' mechanical properties mainly depend on the relative density, the unit cell topology, the manufacturing processes, and the base material. In this research, PA12 lattice structures with non-auxetic strut-based topologies, including BCC, FCC, FCCz, FBCC, FBCCz, FBCCxyz, and OT, were manufactured by selective laser sintering (SLS) and were tested under quasi-static compression. Data from the compression test was analyzed and investigated to achieve mechanical properties such as strength, elastic modulus, and absorbed energy. OT has the highest yield strength (4.07 MPa), ultimate strength (4.53 MPa), specific ultimate strength (10.11 MPa), elastic modulus (0.099 GPa), specific elastic modulus (0.221 GPa), and plateau stress (9.98 MPa) among the investigated sturt-based topologies. BCC has the lowest properties. The absorbed energy (W) for OT and FBCCxyz is higher than in other topologies. FBCCz has the highest volumetric energy absorption (WV) (0.284 MJ/m3) up to the strain of the UTS point, and FCCz has the lowest (0.152 MJ/m3). The finite element method (FEM)-based ABAQUS software was used to simulate the behavior of LSs under compression test. Also, SEM micrographs of struts' fractured surfaces in the CP lattice block were investigated. In most strut-based LSs, the failure mechanism is the layer-by-layer failure of rows. According to finite element modeling results, stress concentration occurred in the nodes and adjacent areas, making cracks, and fractography exhibited ductile fracture in these regions.

Keywords

• Lattice structure
• PA12
• Mechanical properties
• Fractography
• Energy absorption
• Finite element method