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Response of coupled frictional contacts to cyclic loading.

機(jī)譯：耦合摩擦接觸對循環(huán)載荷的響應(yīng)。

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摘要

In this study, the response of coupled frictional contact problems to cyclic loading is investigated. We first consider the receding contact problem for the important case where the loading contains a mean and a periodic component. Dundurs (1975) has shown that if the contact area in a frictionless elastic system under load is equal to or smaller than that before loading, the extent of the contact area is load-independent, and the stress field varies linearly with load. Similar results apply to problems with Coulomb friction as long as the loading is monotonic, but otherwise the system approaches a steady periodic state relatively slowly, and in this final state there is continuous variation of the contact area, with the minimum occurring at the minimum applied load.;Second, we explore whether Melan's theorem can be applied to the coupled system. The evolution of the system history is conveniently represented graphically by tracking the instantaneous condition in the slip-displacement space. The frictional inequalities define directional straight line constraints in this space that tend to 'sweep' the operating point towards the safe shakedown condition if one exists. However, if the safe shakedown region is defined by a triangle in which two adjacent sides correspond to the extremal positions of the two frictional constraints for the same node, initial conditions leading to cyclic slip can be found.;Finally, we study an analytical method to predict friction-induced instability for the case where Coulomb friction conditions may fail to define a unique solution for a quasi-static evolution algorithm. In an attempt to resolve this problem, we develop an elasto-dynamic formulation by introducing the effect of viscous damping. As a result, we find that the final state is determined by the particular values at the discontinuity point. Therefore, it is possible for us to define the unique final state of the system without involving the transient dynamic analysis.
機(jī)譯：在這項研究中，研究了耦合摩擦接觸問題對循環(huán)載荷的響應(yīng)。對于載荷包含平均值和周期分量的重要情況，我們首先考慮后退接觸問題。 Dundurs（1975）表明，如果無摩擦彈性系統(tǒng)在載荷作用下的接觸面積等于或小于載荷作用前的接觸面積，則接觸面積的大小與載荷無關(guān)，應(yīng)力場隨載荷呈線性變化。只要載荷是單調(diào)的，類似的結(jié)果也適用于庫侖摩擦的問題，但是否則，系統(tǒng)會相對緩慢地接近穩(wěn)定的周期性狀態(tài)，并且在此最終狀態(tài)下，接觸面積會連續(xù)變化，在施加的最小值處出現(xiàn)最小值其次，我們探索梅蘭定理是否可以應(yīng)用于耦合系統(tǒng)。通過跟蹤滑動位移空間中的瞬時條件，可以方便地以圖形方式表示系統(tǒng)歷史的演變。摩擦不等式在該空間中定義了方向性直線約束，如果存在，這些約束會趨向于將工作點“掃向”安全擊落條件。但是，如果安全減震區(qū)域由三角形定義，其中兩個相鄰邊對應(yīng)于同一節(jié)點的兩個摩擦約束的極值位置，則可以找到導(dǎo)致循環(huán)滑移的初始條件。最后，我們研究一種分析方法在庫侖摩擦條件可能無法為準(zhǔn)靜態(tài)演化算法定義唯一解的情況下預(yù)測摩擦引起的不穩(wěn)定性。為了解決這個問題，我們通過引入粘性阻尼效應(yīng)來開發(fā)一種彈性動力公式。結(jié)果，我們發(fā)現(xiàn)最終狀態(tài)由不連續(xù)點處的特定值確定。因此，我們有可能定義系統(tǒng)的唯一最終狀態(tài)而無需進(jìn)行瞬態(tài)動態(tài)分析。

著錄項

  • 作者

    Ahn, Young Ju.;

  • 作者單位

    University of Michigan.;

  • 授予單位 University of Michigan.;
  • 學(xué)科 Engineering Mechanical.;Engineering Materials Science.
  • 學(xué)位 Ph.D.
  • 年度 2009
  • 頁碼 123 p.
  • 總頁數(shù) 123
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 機(jī)械、儀表工業(yè);工程材料學(xué);
  • 關(guān)鍵詞

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