多重波峰滑動接觸表面之應力與溫度分析研究

Analysis of Stress and Temperature for Multiply Asperity Sliding Contact Surface

蔡承翰(Cheng-Han Tsai)

指導教授 ： 陳新郁

共同指導教授 ： 洪政豪(Jeng-Haur Horng)

國立虎尾科技大學/工程學院/機械與機電工程研究所/碩士(2015年)

https://doi.org/10.6827/NFU.2015.00199

摘要

研磨或拋光過的物體表面看似光滑平坦，但以微觀角度來看並非如此，其表面是由許多微小的波峰與波谷組成，當兩物體進行相對滑動接觸時，主要是表面間的微波峰進行相互作用造成了摩擦現象，而波峰間的摩擦會對材料之表面溫度與應力應變造成很大的影響，因此有必要了解粗度波峰與材料性能間的關係。
　　本研究使用有限元素分析軟體ANSYS，建立一個多重波峰數的粗糙表面接觸模型，模擬兩物體滑動接觸之情況。考慮不同的波峰數目、表面粗糙度、壓力、滑動速度、熱傳導係數，探討在不同的接觸情況下，其表面接觸溫升與等效應力應變之變化。由分析結果顯示：(一)影響最大上升接觸溫度的主要因素是壓力與速度，隨著這兩項參數數值的增加，其最大上升接觸溫度有明顯增加的趨勢；當表面粗度值愈大時，其最大上升接觸溫度僅略微增加；熱傳導係數與上述影響因素相反，當熱傳導係數愈大最大上升接觸溫度愈低。(二)影響最大等效應力(及等效應變)的主要因素是壓力、波峰數、表面粗糙度，隨著這三項參數數值的增加，其最大等效應力應變有明顯增加的趨勢；隨著速度的增加，最大等效應力僅些微的增加；而熱傳導係數造成之影響與上述影響因素相反，當熱傳導係數愈大最大等效應力愈小。(三) 影響最大剪應力的主要因素與最大等效應力應變之因素相同，壓力與表面粗度增加對最大剪應力增加之影響最大，其次是速度。而熱傳導係數愈大最大剪應力愈小。與最大等效應力較不同的是，在相同的壓力條件下，最大剪應力之位置離接觸面較近，其深度約為最大等效應力的0.60∼0.71倍。

關鍵字

滑動接觸 ； 多重波峰 ； 接觸溫度 ； 等效應力 ； 粗糙表面

並列摘要

The object after grinding or polishing seems to be smooth and flat on the surface, but it is not from the microscopic point of view, based on which the surface consists of multiple micro peaks and valleys. When two objects are sliding relatively, the micro peaks between the surfaces will contact to result in friction. The friction between the peaks shows great influence on the surface temperature, stress and strain of the material. Therefore, it should learn the influence of the asperity peaks and material property on them.
　　The study applies the Finite Element Analysis software ANSYS to build a rough surface contact model with multiple peaks, which is used to simulate the sliding contact of two objects. Considering different peaks, surface roughness, pressure, sliding velocity and thermal conductivity, it explores the changes of contact temperature rise, von Mises stress and von Mises strain under different contact situations. The analysis results show: (1) The major parameters that influence the maximum contact temperature rise are the pressure and the velocity. With the increase of these two parameters, the maximum contact temperature rise shows a significant increasing trend. When the surface roughness is larger, the maximum contact temperature rise only increases slightly. The thermal conductivity shows opposite influence. Namely, when the thermal conductivity is larger, the maximum contact temperature rise is lower. (2) The major parameters that influence the maximum von Mises stress(and von Mises strain) are the pressure and the surface roughness. With the increase of these two parameters, the maximum von Mises stress shows a significant increasing trend. However, with the increase of velocity and thermal conductivity, the maximum von Mises stress only increases slightly. The maximum stress depth of the lower surface is increased with the increase of pressure, and decreased with the increase of velocity and surface roughness. Moreover, the thermal conductivity doesn’t show influence on the maximum stress depth. (3) The major parameters that influence the maximum von Mises strain are the pressure and the surface roughness. The maximum von Mises strain is increased greatly with the increase of the pressure and the surface roughness, and is increased slightly with the increase of the velocity. However, it is decreased with the increase of the thermal conductivity. The maximum stress depth of the lower surface is increased with the increase of pressure, and decreased with the increase of surface roughness. Moreover, it won’t change with the thermal conductivity or velocity. The difference between the maximum shear stress and the maximum von Mises stress is that the former is closer to the contact area under the same pressure condition, with the depth of almost 0.60∼0.71 times of the latter.

並列關鍵字

Sliding contact ； Multiple peaks ； Contact temperature ； von Mises stress ； Rough surface

參考文獻

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