Investigation of mechanical properties of laser powder bed fused AlSi10Mg lattice structures using GTN damage model

Abstract

Lightweight lattice structures can have their mechanical properties and failure modes predicted through computer simulation. This approach has great potential for use in aerospace, the automotive industry, and defense equipment. However, due to the limitations of the LPBF process, fabricated lattice structures contain internal defects that affect the compression response, which leads to high-level errors in finite element method (FEM) predictions and experimental results. Thus, in this paper, a finite element model considering the effect of pore defects was built by using finite element simulation in connection with the Gurson-Tvergaard-Needleman (GTN) damage model to investigate the compressive behavior and mechanical response of the body-centered cubic lattice structure of AlSi10Mg alloys prepared by the LPBF process. A three-dimensional reconstruction of the molded BCC lattice structure was performed by computed tomography (CT) to obtain the structure's distribution and shape of micropores. Using a combination of simulation (FEM-GTN) and experimentation, the effects of process parameters on the compressive properties and mechanical behavior of the BCC lattice structure during quasi-static compression were investigated. The results show that the FEM simulation results corrected by the GTN damage model are in better accordance with the experimental results (the error rate is reduced by more than 10 %) compared to the FEM simulation results without considering the influence of the pore defects, which proves the higher accuracy of the FEM-GTN simulation model. This work provides a reference for the property prediction and fabrication of high-performance, lightweight lattice structures.

Keywords

• Laser powder bed fusion
• Gurson-Tvergaard-Needleman model
• Lattice structures
• AlSi10Mg
• Finite element method