• fem
• wear
• hip prostheis
• bilateral wear
• metal-on-metal
• MoM
• Ansys

The aim of this thesis was to develop a finite element wear model of a metal-on-metal hip implant, in order to examine the bilateral wear effect, considering two different wear coefficients for the cup and the head. The wear model which the study was based on is the one proposed by Archard's law, in particular by deriving from it the wear coefficients proper to each component. The simulations were focused on the modifications of the contact features, such as the type of contact and the algorithm, to obtain the best bilateral fit. Starting from the 2D pin-on-plate models, it was possible to evaluate the best parameter set-up for the bilateral wear model with different wear coefficients (K). Then the 3D model representing the ball-in-socket hip joint was implemented. Two different models were studied, the most important difference between them is the direction of the force, as in one model it remains fixed with respect to the global reference system and in the other it remains fixed with respect to the head, which however moves and rotates on its own reference system. In order to overcome the limits imposed by the software, tests were also carried out on different geometries that were comparable to the starting ones. An example of this is the case of a hollow sphere with another spherical body inside. Indeed, the use of different wear coefficients is important to predict the prostheses wear. This is because a higher coefficient in the femoral head leads to greater and more rapid deterioration of the part, which can lead to structural failure as well as loss of particles, which is harmful to the surrounding tissues.