The Effects of Surface Roughness on the Squeeze Film Characteristics with Couple stress fluids in Hip joint

Abstract

On the basis of the Stokes micro continuum theory , This paper aims to study the effects of surface roughness and couple stress on the squeeze film Characteristics in hip joint. The cartilage is modeled as biphasic poro-elastic  matrix and synovial fluid is modeled as couple stress fluid  . Compared to the conventional Newtonian lubricant case, the couple stress and surface roughness effects characterized by the couple stress and surface roughness parameter signify an improvement in the squeeze film Characteristics. Increasing values of the  surface roughness  parameter increases the load-carrying capacity and the squeeze in the squeeze film can be decreased and provides a longer time to prevent sphere –plane surface contact .The approaching time of the sphere in reducing the film thickness h*=1 to h*= 0for the couple stress fluid lubricant which is longer than surface roughness.

Keywords: Surface roughness, Couple stress fluid, Articular cartilage, Synovial fluid, Micro continuum theory, Hip joint.