Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2729
標題: 圓蓋-球型接觸結構材料磨耗之有限元素模擬
Finite Element Simulation for Material Wear of the Cover-Ball Contact Structures
作者: 許志祥
HSIANG, HSU CHIH
關鍵字: Finite Element;有限元素;Wear;Artificial Hip Joints;磨耗;人工髖關節
出版社: 機械工程學系
摘要: 
在機械零組件接觸所生成的磨耗問題上,實驗量測是一般最常使用之方法,但是量測法在時間與儀器的投資上均相當的龐大,而且所得到的磨耗量也並不完全真確。
在此,將使用有限元素法來解決不連續接觸結構所生成的磨耗問題,其中有兩點值的注意:(1)接觸結構所發生的能量傳遞不連續問題,在此將使用適當的有限元素法技巧來獲得接觸應力。(2)磨耗模式如何導出的問題,在此將以Archard磨耗定律為基礎來做推導。故本文將以此發展出一套三維接觸結構在長時間相互滑動時的數值模擬法來分析磨耗量,並獲得可靠且可供使用的的結果。
髖關節置換術後最嚴重之問題,乃是鬆脫現象的發生與聚乙稀髖臼杯的磨耗,此現象會導致置換術失敗,像這些磨耗問題在置換術後是相當常見的。上述的磨耗現象是由聚乙稀髖臼杯與人工髖關節頭部間接觸區域的摩擦所引起,此種接觸結構類似於圓蓋-球型軸承結構。諸如此類的軸承結構,像是人工髖關節等,有限元素模式可被建立並分析出磨耗量、磨耗深度、應力值等結果。
一般而言,在大部分發表過的文獻上均以臨床量測或是實驗模擬取得置換術後的磨耗資料,但這些資料散布的範圍甚廣,在設計或改良人工髖關節時無法提供一定的準則。故在此本文將提出可靠與最佳的設計準則,來避免置換術後因磨耗所產生的鬆脫現象,使人工髖關節置換術有較長的植入壽命。由於正確的結果是需要合理的磨耗物理現象來配合,這也顯示在模擬過程中,模擬流程與模式建立是相當的重要。其他類似之機械零組件相關問題亦可因循相同的理論與程序處理之。

Measurements are usually used to study the wear problems occurred in the mechanical contact components. However, such measurements are rather expensive in either time or the instrumental investment. Besides, results of the measured wear data are mostly disputable.
Here, in the study of the wear problems occurred in the discontinu-ous, contact structures using the finite element strategy, two points are considered: (1) Problem of solving the energy transfer difficulties be-tween the discontinuous, contact structures; This is solved by proper fi-nite element formulations on basis of the contact normal and shear stresses, and (2) Problem of deriving the wear quantities; This is solved by using the Archard wear law. In this study, numerical simulations for the analysis of the wear in three-dimensional contact structures during long-time, reciprocal sliding motion may thus be developed and signifi-cant results are provided and discussed.
The most severe problems in total hip arthroplasty are components loosening and the wear of polyethylene acetabular components, which may cause the arthroplasty to fail. Such wear problems in the process of the replacement of the artificial hip joints (AHJ) is quite often and popu-lar after surgery. The friction of the contact region between the polyeth-ylene cup and prostal bone-head in the AHJ mainly causes these wear phenomena which is most like a cover-ball bearing structure. Finite ele-ment models for such bearing-like structure in AHJ are developed and related results, e.g., the amount of wear, the depth of wear, the wear stresses, etc..
In general, the wear data obtained after arthroplasty in most of the published papers, either from clinical collection or experimental results, distributes too wide to be used as the designing criteria of the AHJ. How-ever, optimum and reliable designing criteria to avoid loosening along with the wear happened in the AHJs provided here are quite significant. The data provided here may thus give longer life for the replacement of AHJs. The current results compared to some available physical properties of wear, come out the singnificance of the algorithms and models devel-oped. Similar wear problems of any other machine elements can also be refereed use the formulations and solving procedures discussed in this paper.
URI: http://hdl.handle.net/11455/2729
Appears in Collections:機械工程學系所

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