Numerical simulation of the rheology of alumina abrasive particles applied to UHMWPE during the microabrasion test

The material used for 50 years in orthopedics for joint replacements is ultra-high molecular weight polyethylene (UHMWPE). Joint replacements are designed so that the metal is in surface contact with the polymeric material, and it is used in most degenerative joint disorders. A problem with joint replacements is the half-life of their UHMWPE components resulting from surface contact, leading to premature wear. This leads to the detachment of wear particles causing osteolysis. In the present investigation, a numerical simulation of the rheology of 5 mu m size alumina abrasive particles applied to UHMWPE type GUR 1020 was performed by duplicating the microabrasion test. An analogy was proposed between the alumina particles observed in the scanning electron microscope (SEM) and the gravel stone obtaining a geometry similar to that of the alumina particles. A 3D scanner was used, obtaining different randomly selected gravel models. They were scanned and rendered to obtain the IGS files to be used in the finite element software. Using Archad's abrasive wear theory, the volume displaced by the abrasive particles was obtained as a function of the geometry of the abrasive grains, influenced by the entry position of one or more of the different cutting edges contained in the geometry, the hardness of the softer material, the value of the normal load and the sliding distance. Individual trace profiles were obtained by 2D profilometry and wear traces were analyzed by SEM. Explicit dynamic analysis of particle motion was used to simulate the entry, transition and displacement during the abrasive wear test caused by detached particles. The experimental results of the microabrasion test were compared with finite element analysis, demonstrating that simulation can be used as a reliable tool to obtain information about the type of wear of a material.