Evaluation of Fatigue Life of Additively Manufactured Ti6Al4V Neovius Lattices in Simulated Body Fluid for Biomedical Applications

Abstract

Additive manufacturing (AM) using laser powder bed fusion (LPBF) enables the fabrication of intricate biomimetic structures, such as triply periodic minimal surfaces (TPMS), which hold significant potential for biomedical implants. However, the fatigue performance of these structures is often compromised by surface roughness and internal defects. In this work, Triply periodic minimal surface (TPMS) based lattices were fabricated using the LPBF process. Quasi-static compression tests and computational fluid dynamics (CFD) simulations were conducted to determine mechanical properties. and to evaluate permeability and wall shear stress of the lattices respectively. Moreover, High-cycle fatigue testing under compression-compression cyclic loading was performed to determine endurance limits. To further improve its endurance limit, surface modification was carried out using shot peening. Additionally, the influence of a simulated physiological environment on fatigue behaviour was assessed by testing fatigue in Simulated Body Fluid (SBF). Results revealed that surface modification increased the endurance limit under ambient conditions by 20%. However, fatigue testing in SBF revealed a 32% reduction in the endurance limit of surface-modified samples, emphasizing the detrimental effects of physiological conditions. These findings highlight the importance of surface modification and environmental factors in the design of biomimetic implants.