臺灣博碩士論文加值系統

目前各種微型機械元件與精密機械在經由精密加工後，其表面粗糙度尺寸已達到微米等級，在看似光滑平坦之元件表面，若以微觀角度觀察，可以發現其表面充滿許多微小且高低不等之波峯與波谷，當兩元件進行相對接觸運動時，主要是由表面波峯之頂點接觸以造成摩擦之現象。當連續並長時間之摩擦時會使元件接觸波峯表面與內部之溫度上升與材料變形，進而導致材料劣化、精度降低與元件失效等現象，因此在元件間之接觸關係值得研究與探討。
本論文使用有限元素分析軟體模擬兩物體在滑動接觸時，物體表面波峯頂點之接觸表面與內部之性質變化分析，首先以三維繪圖軟體繪製上、下兩滑塊之接觸模型，上滑塊為表面波峯頂點粗糙模型以模擬元件真實表面上高低不等之波峯與波谷，下滑塊為光滑表面模型，接著將模型結合有限元素分析軟體模擬兩物體真實狀況下滑動接觸之情況；進而探討在不同條件下，表面波峯頂點之接觸表面、內部溫升參數與應力應變變化，其中條件包含表面波峯頂點數、施加壓力、滑動速度與熱膨脹係數。
本論文之研究結果顯示：(一)在進行相對運動時會因為摩擦產生熱量，熱量會集中於接觸波峯頂點周圍之表面部份，由波峯接觸表面向周圍與內部傳遞。(二)在進行相對運動時，會因為熱殘留現象造成後段波峯會受殘留熱量影響，因此最高溫升會發生於與滑動相反方向之最後段波峯處。(三)在本論文中，相較於壓力，滑動速度對於最大溫升參數影響較為明顯。(四)壓力增加時會造成波峯接觸產生擠壓變形更為明顯，促使波峯頂點與非接觸區表面間距離減縮，導致熱量更容易傳遞至非接觸區部份，因此相較於滑動速度，壓力對於非接觸區部份溫升影響較大。(五)在高滑動速度運轉條件下，接觸波峯頂點周圍會有剪應力與等效應力發生，因此機械元件在機構中高速度運轉時，除了表面接觸部分會造成磨損，接觸區域周圍結構也可能是破壞危險區。(六)接觸波峯表面之正剪應力會大於負剪應力，但隨著深度增加，負剪應力會逐漸增加，與正剪應力呈現反對稱形狀，其值扔小於正剪應力；而波峯內部之最大正、負剪應力皆在於波峯底部，並且發生於接觸面邊界部分。(七)在高滑動速度條件下，波峯周圍非接觸區部份所產生之等效應力是受熱應力所影響。(八)最大等效應力發生深度會隨著壓力增加而增加，最大等效應力會發生於與滑動相反方向之接觸面邊界處，因此機械元件在機構中運轉反方向之接觸界面內部容易是材料結構破壞起源。

At present, the surface roughness of various micro-mechanical components and precision machinery has reached the micron level after precision machining. From a microscopic perspective a scemingly smooth surface and flat component can be seen that the surface is filled with many asperity and valley with different ups and downs. When the two elements cause the relative contact movement, it is mainly the two asperity contact of the surface that causes friction.It causes the temperature rises on the surface of the asperity and the internal of the elements also causes the material when continuous and long term frictional contact, resulting in material deterioration, precision degradation, and component failure. Therefore, the contact relationship between components is worthy to study and discussion. The upper slider is a rough model of asperity sirface to simulate the asperity and valleys on the real surface of the component, and the lower slider is a smooth surface model.
In this paper, finite element analysis software is used to simulate the variety of the contact surface and internal properties of the contact spot, when the two objects are in sliding contact. First of all, draw the contact model of the upper and lower sliders with 3D drawing software. Then the model is combined with the finite element analysis software to simulate the situation of the sliding contact between the two objects by the real conditions. Furthermove, we investigated the temperature variety parameter and stress contact surface and the internal of the elements. The conditions included the number of contact spot, pressure, sliding velocity and thermal expansion coefficient.
The results of this paper shows: (1) The friction heat is generated when the relative motion is performed, and the heat is concentrated on the surface part of the asperity, and it is transmitted to the periphery and the inside by the contact surface of the wave. (2) When the relative motion is performed, the latter peak will be affected by the residual heat due to the heat residual phenomenon, so the highest temperature rise will occur at the last peak in the opposite direction to the sliding. (3) In this paper, compared with the pressure, the sliding speed has a significant effect on the maximum temperature rise parameter of the upper slider. (4) When the pressure increases, it will cause the asperity contact surface of the ware to produce extrusion deformation, which will reduce the distance between the asperity of the wave and the surface and make the heat transfer to the body more easily. Therefore, when the pressure incress on the upper sliding has the greater impact of the temperature rise, compared with the sliding speed. (5)For high sliding speed operation conditions, shear stress and equivalent stress around the asperity. Therefore, when a high speed operating condition at the mechanical element, in addition to the surface contact part will cause wear, also the structure around the contact region may be damaged. (6) The shear stress of the contact peak surface is greater than the negative shear stress, but as the depth increases, the negative shear stress will gradually increase, and the positive shear stress will exhibit an antisymmetric shape, and its value will be less than the normal shear stress; The maximum positive and negative shear stresses are at the bottom of the peak and occur at the boundary of the contact surface. (7) At the high sliding speeds, the von mises equivalent stress is generated by the non-contact area around the peak is affected by thermal stress. (8) The maximum equivalent stress occurrence depth will increase by the pressure rise, and the maximum equivalent stress will occur at the boundary of the contact surface opposite to the sliding direction. Therefore, the mechanical element is in the opposite direction of the contact interface in the mechanism., usually the origin of the material structure damage.

摘要.......................................................................i
Abstract.................................................................iii
誌謝.......................................................................v
目錄......................................................................vi
表目錄..................................................................viii
圖目錄........................................................................ix
符號說明.....................................................................xvi
第一章 緒論與文獻回顧...........................................................1
1.1 前言與緒論.................................................................1
1.2 研究動機...................................................................2
1.3 論文架構...................................................................3
1.4 文獻回顧...................................................................5
1.4.1接觸溫度文獻回顧..........................................................5
1.4.2 應力應變文獻回顧.........................................................6
第二章 理論基礎................................................................8
2.1 赫茲接觸理論..............................................................8
2.2 熱傳理論...............................................................11
2.3 接觸溫度概論...........................................................14
2.4 摩擦熱理論.............................................................15
2.5 溫度增量方程式.........................................................15
第三章 有限元素分析軟體簡介與問題求解分析.....................................16
3.1 ANSYS有限元素分析軟體發展概述...........................................16
3.1.1 有限元素法起源與介紹..................................................16
3.1.2 ANSYS有限元素分析軟體發展.............................................16
3.2 ANSYS原理與分析過程概述.................................................17
3.2.1有限元素法基本原理(Finite Element Method, FEM).........................17
3.3模擬之模型尺寸與運轉條件介紹.............................................21
3.4模型之上滑塊表面粗糙度介紹...............................................22
第四章 結果與討論..........................................................26
4.1波峯接觸變形............................................................34
4.1.1波峯表面之正向應力分佈與接觸間隙........................................34
4.1.2上滑塊最大正向應力值比較...............................................34
4.1.3波峯內部之正向應力分佈與接觸間隙........................................35
4.1.4接觸變形與接觸面積比較.................................................35
4.2波峯接觸表面與內部溫升分佈...............................................46
4.2.1波峯表面之溫升分佈與接觸間隙...........................................46
4.2.2波峯內部之溫升分佈與接觸間隙...........................................47
4.3波峯接觸表面與內部應力...................................................54
4.3.1波峯表面之剪應力與應變.................................................54
4.3.2波峯內部之剪應力與應變.................................................55
4.3.3波峯表面之等效應力與應變...............................................55
4.3.4波峯內部之等效應力與應變...............................................57
第五章 結論與建議..........................................................73
5.1溫升參數之變化與比較.....................................................73
5.2應力應變之變化與比較.....................................................74
5.3未來展望................................................................75
參考文獻...................................................................76
Extended Abstract.........................................................79

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