A Numerical Investigation About Shrink Line Formation in TPMS Lattice Structures During LPBF Process

Abstract

Thermal nature of laser powder bed fusion process (LPBF) causes residual stress formation on the part during printing which may cause penetration of some layers towards inside or outside of the nominal geometry called shrink line. Shrink line affects dimensional accuracy and fatigue life of produced parts. The prediction of shrink line formation via numerical methods is important to mitigate the high cost of trial-and-error printing. This study focused on shrink line formation prediction in triply periodic minimum surface (TPMS) lattices produced by LPBF process. The effect of TPMS type, volume fraction, unit cell size, inclination angle of the lattice with respect to build platform, functional grading and material on shrink line formation were investigated. Numerical results revealed that shrink lines were formed only on Primitive lattices and input or control parameters used in this study directly influence the shrink line penetration depth due to different thermally induced stress formation between successive layers.