Wear Prediction of UHMWPE Acetabular Cup against CP Titanium Femoral Head in a Hip Joint Simulator

Ultra high molecular weight polyethylene (UHMWPE) is a biomaterial used for the human hip joint prosthesis bearings for decades. The main disadvantage is the wear resistant. The products should be in service in the lifetime of the patients. Tribological assessments by experiments and computations should be made to solve that problem. The aim of this research is to predict the UHMWPE acetabular cup wear volume sliding against commercially pure titanium (cp Ti) femoral head in a hip simulator. The cp Ti has the highest biocompatibility compared with other femoral head metals such as cobalt chrome, titanium alloy and 316L stainless steel. Computation processes use the Abaqus contact mechanics algorithm followed by a custom made Python script for the data extractions and Archard wear model calculations. Models were an assembly of the UHMWPE acetabular cup and 32 mm cp Ti femoral head in a biaxial rocking motion hip simulator. Sliding between the models was a 60 cycles per minute rotation. Calculations conducted for one million cycles cumulative polymer wear volume in five steps of 200,000 cycles. The geometries of the models were updated in every step. Experimental pin on disc tests conducted to obtain the wear factor and coefficient of friction. Those data support the input of computations. Wear volume verification use the experimental data from Rostlund. Results show a numerical error at 31.42 percents.