Fatigue life assessment of orthopedic plates made of Ti6Al4V

Abstract

This study is aimed to analyse fatigue life of orthopedic plates due to cracks initiated in the stress concentration areas. Material used for this analysis was typical orthopedic alloy, Ti-6Al-4V, strong but not very ductile, meaning also sensivite to cracking, as indicated by its mechanical properties, such as tensile strength, impact toughness and fracture toughness, as well as by high fatigue crack rate, all of them tested and analysed here. Extended finite element method (XFEM) in ANSYS software was used for simulating the fatigue crack growth in 5 orthopedic plates with different geometries. Results for crack length and stress intensity factor vs. number of cycles are given, indicating plate D as the best option regarding residual life. Crack paths are analysed in all 5 plates to explain such a behaviour, indicating benefits of initial crack growth into length, followed by growth into depth. Also, the effect of geometry of plates is considered to explain differences in life predictions for 5 different plates.