Finite element analysis of the total hip joint prostheses against fatigue fracture

number: 
2401
English
Degree: 
Author: 
Nawar Banwan Hassan
Supervisor: 
Dr. Albert E. Yousif
Dr. Mohammed N. Latif
year: 
2010

Abstract: Forces applied to the implant due to human activity generate dynamic stresses varying in time and resulting in the fatigue failure of implant material. Therefore, it is important to ensure the hip prostheses against static, dynamic and fatigue failure. This study about two types of implants; the Austin Moore, cemented Thompson, and cementless Thompson hip replacements. The three dimensional solid models were built using AutoCAD 2007 software and then transferred to the finite element software (ANSYS Workbench). The resulting stresses were highlighted in every case by changing the alloy type using three types Ti6Al4V, Stainless Steel 316L, and Cobalt Chromium alloys. The bone considered healthy and the implant well fixed. The materials were considered a homogenous, isotropic, and linearly elastic. The static load applied which was the maximum stumbling load resulting in Maximum Von Mises stresses in the Austin Moore hip replacement when using the Cobalt Chromium alloy was 254.42MPa.The dynamic loading was as loading history for five seconds, resulting in Maximum Von Mises stresses in the Austin Moore hip replacement when using the Cobalt Chromium alloy was 263.37MPa. It was observed that the Maximum Von Mises stresses occurred in the cement mantel was when using the Cobalt Chromium alloy for the implant statically and dynamically respectively was 80MPa and 86MPa. The fatigue analyses were done by using the theories Mean, Soderberg, Goodman, and Gerber theories. It was found that the minimum safety factor was when using the Cobalt Chromium alloy by using the Goodman theory which was 1.1608.The minimum life were found equal to about 23 years in the case of cemented Thompson implant.