Effect of varying unit cell size on energy absorption behaviour of additive manufactured TPMS PETG lattice structure

In this study, a modest attempt has been made to study the effect of varying unit cell size on energy absorption behaviour of additive manufactured Schwarz P Triply Periodic Minimal Surface lattice structure. The four different unit cell sizes called two lattice element, four lattice element, six lattice element and eight lattice element in x, y and z axes were considered in this study. The models were developed using the implicit function equation by considering the required boundary conditions in MathMod software. The Fused Deposition Modelling technique and biocompatible polyethylene terephthalate glycol material were used for this study. The ASTM D695 test procedure was applied over the specimens to find out the amount of energy absorption happened before the failure. The failure modes were analysed with the help of scanning electron microscope images. The results are compared and it was observed that the two lattice specimen exposed the cracks in the middle of the unit cell while the four lattice specimen exposed linear failure between the unit cells from top left to bottom right. The six lattice specimen element shows the horizontal plane failure like a straight line in the lateral direction. The eight lattice element exposes a vertical plane failure observed in vertical direction with respect to the front view projection. The edge distortions and random ruptures inside the portions of the specimens are observed for all the unit cell sizes with no significant penetration. The overall outcomes of the six lattice specimen design provided optimum properties when comparing to other specimens. The outcomes of this study could be further extended for enhancing the knowledge on usage of TPMS structure in bone scaffolding, acoustic, thermal, and piezoelectric applications in an augmented way.