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The Mechanical Study on the Contact Wear Behavior in Artificial Hip Prostheses
|關鍵字:||Artifical Hip Joint;人工髖關節;Acetabular Cup;Wear Rate;聚乙烯髖臼杯;磨耗 速率||出版社:||機械工程學系||摘要:||
本文主要研究項目包括 1.髖關節磨耗機制之實驗文獻探討與分析模式2.建立磨耗分析模式並建立銷對盤磨耗試驗模型進行驗證 3.聚乙烯髖臼杯與金屬及陶瓷關節頭之磨耗分析4.聚乙烯髖臼杯與金屬關節頭之衝擊磨耗 5.聚乙烯髖臼杯接觸破裂分析。
In this study, a numerical simulation technique based on three-dimensional finite element contact model and modified Archard's wear law was proposed to analyze the wear behavior and contact characteristics at the articulating surface of artificial hip prosthesis. For polyethylene acetabular cup against metallic or ceramic heads, current results showed that the estimated wear rates were very closed to the results obtained from clinical measurements and experimental data available in literature. Furthermore, the ratio of wear rates for polyethylene cups against alumina and the metallic femoral heads was 0.5, which agreed well with that deduced from clinical studies or laboratory hip simulators.
Concerning the contact characteristic at the articulating surface, results from finite element analysis showed that the polyethylene acetabular cup was subjected to cyclic loading under normal walking condition. Meanwhile, the maximum principal stress within the acetabular cups is less then the yielding strength. Under such low stress state, the sliding wear was considered as the dominant mechanism of surface damage. However, higher tensile stress was induced when the non-conforming articulating surface was formed owing to surface wear. It has been proved that for acetabular cup with embedded surface crack the stress intensity factor around surface crack will exceed the fatigue threshold of the material. At this moment, that may enable the inception of crack propagation and will cause the bearing surface to break away, which was the mechanism of fatigue wear.
For the investigation on polyethylene wear rate, the proposed numerical approach can provides a more efficient and reliable manner than wear tests on hip simulators or clinical observations, which take considerable time and expense. It is believed that current analysis model also contributes to further investigation on wear problem and future design improvements of the hip prostheses.
|Appears in Collections:||機械工程學系所|
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