Design and mechanical performance of nature-inspired novel hybrid triply periodic minimal surface lattice structures fabricated using material extrusion

The materials found in nature often exhibit intriguing characteristics due to multiple mor- phologies that are architecture and integrated at different length scales. On the other hand, most of the engineered cellular lattice structures possess a less-sophisticated, uniform, and one type of morphology that may not be ideal and optimized. Therefore, the engineered materials possess multiple morphologies/hybrid lattices can exhibit higher performance and advantages to achieve desired properties. In this work, hybrid lattice structures are designed by incorporating surface-based triply periodic minimal surface (TPMS) structures that are constructed using implicit equations. Six samples were designed that include four hybrid (Diamond, Gyroid, Lidinoid, Split P are joined and hybridized linearly in a single sample) and two uniform morphology samples composed of Gyroid, and Diamond TPMS structures. The challenges related to interfaces while joining different morphologies in hybrid samples were addressed properly. For quasi-static compression tests, three specimens for each sample were additively manufactured using PLA material. Mechanical performance in terms of strength, stiffness, energy absorption and failure are studied using experimental and finite element analysis methods. The results show that hybrid HS2 and Diamond structures performance is almost similar at higher strain rates; however, the deformation behavior significantly varied. The deformation mechanics of hybrid structure is greatly different from uniform morphology counterparts. Structures with better connectivity almost deform together and it highly affects the post-yield response of the structure. Uniform morphology structures absorbed energy nearly at a constant stress level; whereas, all hybrid structures possess progressive mode of energy absorption. The hybrid structure HS2 possesses highest specific energy absorption among all structures. Thus, hybrid structures are crucial when used for energy absorption application with a progressive deformation mechanics such as footwear, blast, impact, crashworthiness, and ballistic protection applications.