Modeling And Analysis Of ElastoHydroDynamic Lubrication Aritficial Hip Joint Via Elements Of Absolute Nodal Coordinate Formulation

Artificial hip joints in the process of movement appear complex nonlinearcharacteristics which attract attentions of researchers in recent years. All kinds of artificialhip joints are inserted into the patients of the different demands, and the artificial sphericalbearings in the human body work normally up to15years. However, such a life can notmeet demands of young patients with lots of sports. The outer circumstances and the innerlubricating conditions of the whole system will aggravate the coupling effect among parts,and this can increase aging. In recent years, the elastic acetabulum cup is rising andacetabulum cup material’s elastic modulus becomes lower and lower. It makes the elasticdeformation of the acetabulum cup should not be ignored. Therefore, modeling and analysisof EHD lubrication of artificial hip joints have a great theoretical significance and theengineering application value.On the basis of previous studies, the EHD lubricated artificial hip joints are studied inthis thesis. Three aspects are focused as follow:1. To solve the correspondence problem between oil film difference points and finiteelement model nodes of acetabulum cup and computational efficiency problem, modelingin this paper adopts15nodes pentahedron element and20nodes hexahedron element.Based on the continuum mechanics theory, formulas of efficient elastic forces and Jacobi ofthe15-node pentahedron element of ANCF are deduced. The dynamic simulationeffectiveness of this element and this element combined with20-node hexahedral elementare validated.2. A new ElastoHydroDynamic(EHD) lubricated artificial hip joint model is proposed.The model is modeled by the Absolute Coordinate Based (ACB) method which combinesthe Natural Coordinate Formulation (NCF) describing rigid ball bodies and the AbsoluteNodal Coordinate Formulation (ANCF) describing flexible cup bodies.3. The OpenMP parallel computing technology and the generalized-alpha method areused to solve large-scale equations. The formulas of lubricant pressure field arederived,and then they are solved by the MLMG method. Results are validated by using theADINA software.