Mathematical Analysis of Deformation Behavior in Hip Joint Composed of Functionally Graded Material and Optimization of Material Composition by GA

点击翻译按钮获取中文摘要

Functionally graded materials (FGMs) which have been developed as one of light-weight structural materials of the reusable rocket engine and flight body in space-plane, could be also applied to create artificial materials with new properties and functions in the medical field. In this study, a material design is performed for the artificial acetabular cup composed of functionally graded material having the bioactivity able to bond to living bone and the function of stress relaxation. The artificial acetabular cup is assumed to be a non-homogeneous hollow hemisphere with arbitrary non-homogeneous mechanical properties only in the radial direction, and then the static and dynamic stresses and displacements in the hemisphere subjected to axisymmetric static and impulsive loadings on the inner spherical surface, are analyzed mathematically, and numerically by using finite element method. The following three analysis models are used : (a) UHMWPE cup fixated to bone with PMMA bone cement ; ( … More b) UHMWPE cup fixated to bone with interface bioactive bone cement ; and c UHMWPE cup with porous AW-glass coating fixated by bone ingrowth into the pores of the coating layer. Furthermore, the contact stress in the functionally graded material artificial hip joint is analyzed. The wear of UHMWPE is a major obstacle limiting the longevity of implanted artificial hip joint. It is now well known that the wear debris of UHMWPE acetabular cup initiates a cascade of adverse tissue response leading to osteolysis and loosening of the article hip joint. Extending the longevity of total hip joint replacements by the improvement of wear behavior has been the subject of ongoing research in the orthopaedic community. The major factor of the UHMWPE wear is the cyclic contact stress. So, material design based on FEM elastic stress analysis is presented for the artificial acetabular cup composed of functionally graded material having the bioactivity able to bond to living bone and the relaxation function of stress on the contact surface and its neighborhood of the femoral head and the acetabular cup subjected to dynamic loadings. Less