Study on the Creep and Creep Relief Behavior of Biomedical UHMWPE under Pin-on-Disc Loading

• Main Authors: Chan, Shinchia, 陳信嘉
• Other Authors: Wei, Monyu
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/22217913315202291826

碩士 === 大華技術學院 === 機電研究所 === 97 === Looseness induced by the wear and creep in Ultra-High Molecular Weight Polyethylene (UHMWPE) is an important problem in artificial joints. It has also been demonstrated on the Pin-on-Disc wear test that the creep deformation induced by alternating stress and the volume loss relating to wear have the similar contribution on dimensional change. In this study, a series of creep and creep relief test under various loading of UHMWPE were carried out on a modified Pin-on-Disc wear machine. A simple three-element mechanical model with elastic, Voigt element and viscous dashpot was used to discuss and then predicting the deformation behaviors of creep and creep relief in such material. The experimental results reveal the elastic element is linear elastic and the Voigt element is also ideal with a constant creep relaxation time (τ) equally to 744min. However, the viscous element hereby is almost steady as the time of loading exceeds 1000min, which is difference from the ideal Newtonian viscous behavior. Regardless of the time independent phenomenon in this region, the viscous strain increases with the increase of creep loads. Finally, the total strain of creep and creep relief can be expressed by the summary of each strain with respect to the various elements. According to the mechanical model mentioned above and experimental results, a method with simple equations proposed here can be used to predict the creep and creep relief deformations behavior under various loads and loading times.