Shell offset enhances mechanical and energy absorption properties of SLM-made lattices with controllable separated voids

Abstract

Additive manufacturing has enabled surface-based sheet lattice to emerge as a new mechanical metamaterial with exceptional weight specific strength properties and multifunction. A novel design method of shell offset has been developed here for enhancement of mechanical properties and domain controllability of separated spaces by sheet lattice. Using selective laser melting, Ti6Al4V lattice samples were fabricated for compression experiments, followed by Micro-CT reconstruction. Manufacturing deviations with mean values of statistical analysis were taken into numerical simulations for prediction of mechanical properties. Investigation results show that increasing the shell offset is an effective strategy to improve mechanical properties and energy absorption of sheet lattices by more than 200% competing with net lattices, which is attributed to the higher second moment of area and successive layer-by-layer deformation mechanism of optimized unit type. In addition, a feasible adjustment region of 30–55% has been found, in which spatial volume fraction of the two independent void phases can be controlled for flow regulation of heat exchange without changing their mechanical properties. Those design concepts of sheet lattices will be valuable in future thermal management applications with lightweight protection.

Keywords

• Selective laser melting
• Sheet lattice
• Triply periodic minimal surface
• CT reconstruction
• Mechanical behaviour
• Energy absorption