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

功能梯度材料作为可重复使用的火箭发动机和航天飞机飞行器的轻质结构材料之一，在医学领域也可用于制造具有新性能和新功能的人工材料。本研究对具有与活骨结合的生物活性和应力松弛功能的功能梯度材料组成的人工髋臼杯进行材料设计。将人工髋臼杯假设为仅在径向上具有任意非均匀力学性能的非均匀空心半球，然后利用有限元法对半球内球面承受轴对称静载荷和冲击载荷时的静、动应力和位移进行了数学分析和数值计算。使用了以下三种分析模型：（a）使用PMMA骨水泥固定到骨上的UHMWPE髋臼杯;（ ...更多信息 B）使用界面生物活性骨水泥固定到骨上的UHMWPE髋臼杯;和c使用多孔AW-玻璃涂层的UHMWPE髋臼杯，通过骨长入涂层孔内进行固定。在此基础上，对梯度功能材料人工髋关节的接触应力进行了分析。超高分子量聚乙烯（UHMWPE）的磨损是限制人工髋关节植入寿命的主要障碍。现在众所周知，UHMWPE髋臼杯的磨屑会引发一系列不良组织反应，导致骨溶解和供试品髋关节松动。通过改善磨损行为来延长全髋关节置换术的使用寿命一直是骨科界正在进行的研究的主题。UHMWPE磨损的主要因素是循环接触应力。因此，本文提出了基于有限元弹性应力分析的人工髋臼杯材料设计方法，该材料由具有与活骨结合的生物活性的功能梯度材料组成，在动态载荷作用下股骨头与髋臼杯接触面及其附近具有应力松弛函数。少

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