The Geometrical Effect on the Von Mises Stress on Ball and Socket Artificial Discs

Wear has been considered as a major issue for ball and socket artificial discs. This paper studies the effects of ball radius and radial clearance of the artificial disc on the von Mises stresses. Different material combinations, used in artificial discs, are compared. FEA simulation using Solidworks has been conducted for different disk geometries. The highest von Mises stress was 714MPa for 10mm radius metal against metal design. The lowest von Mises stress was 14.8MPa for 16mm radius of the UHMWPE/CoCr material combination, which exhibited the lowest von Mises stresses for all the radii of the ball and socket articulation. Considering radial clearance, the lowest von Mises stress was 14.8MPa for 0.015mm clearance of the UHMWPE/CoCr combination. The highest von Mises stress of 100.8MPa with a radial clearance of 0.25mm was recorded for the same combination. There is a strong relation between the von Mises stress and the geometry of the ball and socket of the artificial disc.