Enhancement in the mechanical behaviour of a Schwarz Primitive periodic minimal surface lattice structure design

• An improved Schwarz primitive lattice structure with small openings was proposed. • Compression tests and FE simulations were conducted to evaluate their performances. • The compressive strength and energy absorption of new lattices have greatly increased. • A rigid-plastic hardening model was introduced to predict the mechanical response. Triply periodic minimal surface (TPMS) sheet lattice structures are composed of continuous and smooth shells, enabling the achievement of a high surface-to-volume ratio and pore interconnectivity, which represent an emerging solution for lightweight applications. In this study, an improved Schwarz primitive lattice (P-lattice) structure was proposed by redefining the original opening diameter with a shape parameter. Prototypes of different configurations, such as the original P-lattice (OP) structure, modified P-lattice structure with a small opening diameter (SP), and modified P-lattice structure with a big opening diameter (BP) were fabricated via micro-selective laser melting using 316 L stainless steel. Quasi-static compression tests were performed on the fabricated samples. The experimental results indicated that the Young's modulus, compressive strength, and energy absorption of the SP lattice were increased by 25.84%, 15.63%, and 33.02%, respectively, compared with those of the OP structure. A finite element model was established to investigate the mechanical properties and energy absorption of all the designed configurations, and the results showed good agreement with the experimental observations. A rigid–plastic hardening model was also introduced to macroscopically predict the mechanical response and energy absorption of the as-designed lattice structures. The mechanical properties and energy absorption of the SP structure outperformed those of the OP and BP structures.