HAp-Ti-6Al-4V Interface Fretting Wear Failure Prediction in Different Bio-lubricants using FEM

Abstract

Plasma-sprayed hydroxyapatite (HAp) coated titanium alloy (Ti-6Al-4V) has been widely used as the material for artificial hip implants. However, studies have greatly challenged their long-time usage due to fretting wear behavior at the HAp-Ti-6Al-4V interface. Wear particles from the HAp coating may activate inflammation at surrounding organs, further leading to implant loosening, implant failures and even total hip replacement (THR) revision surgeries. Hence, present research aims to adopt the finite element methodology (FEM) in predicting fretting wear failure at the HAp-Ti-6Al-4V interface of uncemented hip implant femoral stem component under different body environments (bio-lubricants). A finite element (FE) model based on the half-cylinder on flat contact configuration subjected to actual mechanical and tribological properties under different bio-lubricants is developed with the modified Archard wear equation adopted to examine the fretting wear behavior through simulations. A parametric study is then conducted to evaluate the combined effects of different mechanical and tribological properties, including HAp coating thickness, bone elastic modulus and loading condition, under different bio-lubricants on the fretting wear behavior of HAp-Ti-6Al-4V interface. Lastly, single and multiple regression analyses are performed to formulate fretting wear predictive equation that acts as a fast-fretting wear failure prediction tool. The FE predicted results in this paper prove that the maximum wear depth at HAp-Ti-6Al-4V interface is promoted under lower coefficient of friction (COF), smaller HAp coating thickness, smaller bone elastic modulus and larger intensity of fatigue loading. The formulated predictive equations suggest a strong correlation between independent and dependent variables due to R-squared (R2) values being larger than 0.75 which guarantee goodness of fit.