Bio-inspired Ti‐6Al‐4V mechanical metamaterials fabricated using selective laser melting process

Abstract

In the current study, porous architecture of the Euplectella aspergillum has been used to mimic mechanical metamaterial. Modelled metamaterial are fabricated using selective laser melting (SLM) process with Ti-6Al-4V alloy. The fabricated metamaterials are mechanically tested under quasi-static compressive loading condition. The heat treatment effect on compressive behavior and microstructure is also observed. The as-printed metamaterial has strength (173.36 MPa) and fracture strain (2.96%), whereas heat-treatment decreases the strength to (146.08 MPa) and increases the fracture strain to (12.60%). The increase in ductility after heat treatment is due to the formation of β-Ti and decrease in residual stresses. The presence of β-Ti phase is confirmed using microstructural and X-ray diffraction method. X-ray diffraction also confirms the decrease in tensile residual stress value from (179.5 ± 4.5 MPa) for as-printed to (96.5 ± 2.4 MPa) after heat-treatment process. Normal residual stress value is also dependent on the location of measurement on the metamaterial. However, heat treatment and location of measurement have no effect on shear residual stress. In the last, finite element simulation has been carried out to visualize the effect of diagonal struts on the deformation behavior. The result shows diagonal struts in the E. aspergillum based metamaterial helps to prevent global buckling and uniformly distribute the load, hence improves the strength of the metamaterial. • 2D Metamaterials are derived from Euplectella aspergillum • Metamaterials are fabricated using selective laser melting process with Ti-6Al-4V alloy • Mechanical and fracture behavior of the as-printed and heat-treated samples is compared • Bio-inspired metamaterial shows improved buckling resistance properties • Residual stress decreases with heat treatment and it is dependent on the topology