Variable-thickness sheet lattices with controlled fracture performances

This work aims to make an initial attempt to the controllable fracture performances of sheet lattices. Four types of variable-thickness sheet lattices (VTSLs) are designed using the Schwarz-P type triply periodic minimal surface, taking into account the manufacturability of the laser powder bed fusion technique. Three-point bending tests are conducted to investigate the fracture performance of VTSLs. Using ductile damage simulations, the fracture evolution process is analyzed, and mechanisms of fracture initiation and crack interaction are described. Experimental and numerical studies have established that distributions of local materials have a significant impact on fracture patterns, including intracellular and intercellular fractures. Under the same condition, the flexural strength, energy absorption capability, and fracture force can be improved for VTSLs with smooth transitions of neighboring unit cells. Specifically, the strength of VTSLs can be further enhanced when the homogenized material model is used. This work establishes a link between the controllable fracture performance and the additive manufacturing design of VTSLs.