Experimental and Numerical Fatigue Study of TPMS Gyroid Structures Made from Ti6Al4V

Triply Periodic Minimal Surface (TPMS) cellular structures offer high mechanical performance and are increasingly used for load-bearing applications, where fatigue resistance is critical. This study investigates the quasi-static and high-cycle fatigue (HCF) behaviour of laser powder bed fusion (LPBF)-manufactured Ti6Al4V sheet-based Gyroid structures using experimental testing and numerical modelling. Quasi-static compression tests were performed to characterise the structure’s response, load-carrying capacity and collapse. Compression–compression fatigue tests were conducted under force control into compression to establish the structure’s stress life (S−N) curve. The Gyroid exhibited a repeatable compressive response with a pronounced first peak followed by localisation of deformation within a diagonal collapse band. Recorded cycle counts ranged from approximately 104 to beyond 106 cycles over the investigated stress–amplitude range. A shell-based finite-element model was used to determine local stress fields under the experimental fatigue loads, while fatigue life was estimated using the stress life approach. The numerical predictions showed decent agreement with the experimental fatigue trend, supporting the use of local-stress-based modelling for preliminary HCF assessment of TPMS structures.