Energy absorption & stiffness behaviour of additively manufactured novel bio-inspired rhombus-shaped lattice structures: An experimental & numerical investigation

• A Novel type of bio-inspired lattices is developed with varying overlapping areas of rhombus-based geometries of two different cell sizes. • The wall thickness of 0.2 mm has also influenced the performance of the specimens. • Energy absorption and stiffness criteria of all the specimens are analysed with the stress-strain curves. • Scanning electron microscope (SEM) images show the fracture of specimens and resin material distribution of the fractured specimens produced via the vat photopolymerization process. A significant approach inspired by nature is observed in the design of lattice structures, which offers significant enhancements in mechanical characteristics and multifunctionality in the field of lightweight engineering applications. The present research develops a novel kind of unique lattice structures based on the concept of mimicking three different patterns seen in nature. The three patterns are observed from the overlayed structure of scales on fish dermis layers, the scute texture on crocodile species' uppermost skin layers, and the rhombus shaped patterns observed from the deep-sea sponges (Euplectella aspergillum). The geometric size of these lattice structures is limited to 30 cubic millimetres. Two different geometrical sizes of 4 mm and 6 mm are applied in the design of lattice unit cells, with 20, 30, 40, and 50 per cent overlapping portions calculated from each cell area. Each unit cell's walls have been maintained between 0.4 and 0.6 mm. The majority of the fundamental additive manufacturing processes that promise superior dimensional accuracy with few defects in 3D printing (3DP) is the vat photopolymerization method has been employed for manufacturing the designed specimens. The crash-resistant performance of the intended specimens is evaluated by applying quasi-static compressive loading in compliance with ASTM 1621 standards. The experimental and numerical findings show a strong connection with enhanced validation. The 16 specimens are evaluated in real time to determine the most appropriate design parameters for applications of energy absorption in the field of space and aviation sectors.