Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1545
標題: 人工髖關節接觸磨耗行為之力學研究
The Mechanical Study on the Contact Wear Behavior in Artificial Hip Prostheses
作者: 洪瑞斌
HUNG, JUI-PIN
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: 
本研究主要目的是利用有限元素法探討異性材質組合人工髖關節,其關節介面在正常步態週期內之接觸狀態與磨耗現象。研究中透過有限元素法與接觸元素理論,可精確計算髖臼杯介面於磨耗前後之接觸應力變化。再根據符合人工髖關節磨耗機制之磨耗理論,提出三維磨耗分析之數值模擬法則。
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。
本研究針對不同材質組合之髖關節球頭與聚乙烯髖臼杯,進行磨耗分析。其結果顯示,聚乙烯髖臼杯對陶瓷關節頭之磨耗速率小於對金屬關節頭之磨耗速率。就其個別之磨耗速率及其間之比值而言,相較於臨床量測及髖關節模擬實驗之結果,皆顯得相當吻合。這說明各種異性材質組合之人工髖關節,其磨耗行為亦可藉由數值模擬方式進行瞭解與分析。
另外,對磨損髖臼杯而言,其結合面則會因磨耗間隙增加而形成非均勻性接觸,並影響接觸應力分佈。研究發現,此種情形下可能形成更嚴重之磨損現象。此外,若髖臼杯內存有潛在微小裂痕,則此裂痕在衝擊接觸作用下將可能導致表面裂痕擴張,有機會產生嚴重表面損傷之情形。
本文所提出之磨耗分析模式,對於未來人工髖關節在材質開發選擇及結構設計方面,將可提供實質之參考依據。

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.
URI: http://hdl.handle.net/11455/1545
Appears in Collections:機械工程學系所

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