Exploration of the orientational-dependent fatigue response of triply periodic minimal surface cellular structures: A numerical study

Abstract

Recently, Triply Periodic Minimal Surface (TPMS)-based lattices have received significant attraction in structural applications across a variety of engineering sectors, including automobile, aerospace, and biomedical, owing to their improved mechanical properties and lightweight potential. The mechanical characteristics of these lattices are intrinsically linked to the design-related topological descriptors that include the spatial arrangement of their topological cell wall, geometrical sizes, and relative density. In practical applications, however, these structures are often exposed to fuctuating loads that can induce depreciation of their mechanical properties and eventually fatigue failure. Therefore, it is crucial to conduct a comprehensive analysis of their orientational-dependent fatigue response and explore the structure-property correlation under fatigue subjected to various loading conditions. To address this challenge, a novel numerical framework based on the Finite Element Method has been proposed and employed to investigate the fatigue strength of TPMS lattices, specific to uniaxial loading conditions. The stress-based Crossland criterion has been adopted as the fatigue criterion, and the fatigue strength of the considered volume is computed using a fatigue indicator parameter (FIP). The developed framework is undertaken to examine the performance of two widely studied sheet-based TPMS-lattices, namely Schoen Gyroid, and Schwarz Primitive. Besides, the approach permitted to demonstrate the influence of localized material distribution and loading direction towards the evaluation of fatigue strength and structural efficiency. It is observed that among the proposed lattices, Schoen Gyroid is shown to exhibit better fatigue properties in accordance with the existing literature studies. The outcome of these case studies suggests that the proposed numerical framework ofers a promising solution for solving topology optimization problems involving lattices, wherein not only the selection of the lattice but also their preferred orientation can be taken into account as design variables.