Fracture and Fatigue Behaviour of Implants Made of Ti Alloys

Abstract

This paper presents an analysis of Ti alloys used in biomedical applications, such as artificial joint implants and fixation plates, from a fracture mechanics perspective, including fatigue crack initiation and propagation phenomenon. Toward this end experimental and numerical research of mechanical behaviour of fixation plate and hip replacement implant is presented. Experimental analysis was based on standard methods for testing mechanical properties and application of Digital Image Correlation (DIC) technique, while the Finite Element Method (FEM) was used for numerical simulation. Comparison of results indicated a good agreement of experimental and numerical results and reasonable explanation of fixation plate failure. Experimental and numerical research of cracked hip replacement implant is also presented, including fatigue crack propagation, simulated by the Extended FEM (XFEM) using MORFEO postprocessing of ABAQUS stress-strain results. Based on static analysis and fracture toughness properties, the critical crack length was calculated and then used as the final crack length for fatigue life estimation. Toward this end, the Paris law has been used, with coefficients C and m obtained experimentally on RUMUL testing device. The number of cycles needed for failure which has been obtained was in a reasonable agreement with data from case study analysed.