Numerical solution of a 2D lubrication model with Sommerfeld boundary conditions for hip prostheses

BRENDA WEISS; MARCELO E. BERLI; SEBASTIÁN UBAL; JOSÉ DI PAOLO

Paraná

Congreso; VI Congreso Latinoamericano de Ingeniería Biomédica (CLAIB 2014); 2014

Facultad de Ingeniería (Universidad Nacional de Entre Ríos), Sociedad Argentina de Bioingeniería

Prosthetic in-contact surfaces wear is one of the main causes of hip replacements failure. Lubrication is essential to reduce the friction and consequently the wear. A two-dimensional model based on a modified Reynolds equation, was used to analyze the lubricated contact in a hypothetical hip prosthesis. It is assumed that prosthesis is made of a metallic component and a low rigidity elastic porous material that can absorb or exude fluid. The fluid pressure and channel flow shape were simultaneously solved by a double precision computer code based on the finite element method, Newton´s method and parametric continuation. The information provided by this model is extremely difficult to obtain by experimental methods. Results show that a great-er deformation capacity of the elastic material promotes a thicker lubrication film and induces a better load distribution reducing normal stresses; while exudation capacity reduces friction and wear. The sub-ambient pressures predicted and the oscillatory solution, show the need of more realistic boundary conditions and finite element mesh refinement.