本文選題：摩擦模型 + 端面扭動　； 參考：《中國礦業(yè)大學(xué)》2014年碩士論文

【摘要】：本文基于彈性半無限空間理論，建立剛性平?jīng)_頭作用在彈性半無限空間的端面扭動摩擦模型，利用Maple編寫計算程序，獲得了法向應(yīng)力分布，摩擦扭矩與黏著半徑、扭動角的關(guān)系。研制了一種端面扭動摩擦界面實時觀測裝置，開展了PMMA與45#鋼端面扭動摩擦磨損測試，利用高速顯微攝像儀，實時觀測并逐幀分析摩擦界面的黏著區(qū)與滑移區(qū)，獲得了不同載荷和扭動角下界面的實時磨損形貌與循環(huán)次數(shù)的準確動態(tài)關(guān)系。基于MC尼龍和PTFE的試驗數(shù)據(jù)，從摩擦扭矩-扭動角（T-θ）曲線和穩(wěn)定摩擦扭矩等方面進一步驗證端面扭動摩擦模型的正確性，取得的結(jié)論如下： 1、端面扭動接觸中心的法向應(yīng)力最小，而在靠近平底沖頭的棱角處，法向應(yīng)力迅速增加，出現(xiàn)應(yīng)力集中。剪切模量、扭動角、摩擦系數(shù)和法向力四因素綜合改變黏著半徑的大小，即決定了端面扭動的接觸狀態(tài)，它們與黏著半徑成非線性關(guān)系。摩擦扭矩隨黏著半徑整體上呈現(xiàn)先增加直至近邊緣處達到最大值，然后略有減小。 2、PMMA-45#鋼配副的T-θ曲線隨角位移幅值的增加由直線形轉(zhuǎn)變?yōu)闄E圓形最后變?yōu)槠叫兴倪呅巍Ｏ嗤俏灰品迪�，黏著半徑會隨法向載荷的增大而增加。在扭動角為0.1°時，PMMA在法向載荷83N、123N和163N下的理論黏著半徑都為5mm，表明扭動界面處于完全黏著狀態(tài)，而實測的黏著半徑分別為3.8mm、4mm和4.15mm。在扭動角為0.25°時，PMMA在法向載荷83N、123N和163N下的理論黏著半徑分別為1.48mm、3.88mm和5mm，可知扭動界面處于部分滑移或黏著狀態(tài)，而實測的黏著半徑分別為1.88mm、3.2mm和3.4mm。在扭動角為0.5°時，PMMA在法向載荷83N、123N和163N下的理論黏著半徑分別為0.074mm、0.5mm和1.2mm，而實測的黏著半徑分別為0、0和0.5mm，整個界面處于完全滑移狀態(tài)。實測的黏著半徑與理論值較接近，即從黏著半徑與扭動角的關(guān)系驗證了端面扭動模型的正確性。 3、端面扭動界面損傷首先發(fā)生在接觸界面邊緣處，，部分滑移區(qū)表現(xiàn)為擦傷形貌，完全滑移區(qū)則表現(xiàn)為銀紋損傷。隨著循環(huán)次數(shù)的增加，黏/滑邊界處損傷逐漸加重同時向接觸中心擴散，直到循環(huán)結(jié)束，接觸中心仍無損傷。在部分滑移區(qū)，黏/滑交界處出現(xiàn)沿周向不均勻分布的擦傷形貌，且磨痕沿周向不斷生長，逐漸沿徑向拓展，伴隨著輕微的細紋(即銀紋）損傷。在完全滑移區(qū)，銀紋的波紋狀特征非常明顯，銀紋沿徑向產(chǎn)生，經(jīng)歷伸長變寬和模糊消失的過程，最后留下塑性流動的痕跡。相同載荷下，PMMA磨損體積隨角位移幅值的增大而呈略微增加趨勢；相同角位移幅值下，PMMA磨損體積隨著法向載荷的增加而增加。 4、MC尼龍復(fù)合材料和PTFE的扭矩都隨扭動角的增加急劇減小至穩(wěn)定狀態(tài)，端面總扭矩隨摩擦系數(shù)和法向載荷的增大呈線性增加。部分滑移狀態(tài)時的扭矩值高于完全滑移狀態(tài)的扭矩。不同角位移下的實驗扭矩與計算曲線相似，揭示了該扭動摩擦模型可近似預(yù)測彈性變形下聚合物材料的扭矩。
[Abstract]:Based on the theory of elastic semi infinite space, the friction model of the end of rigid flat punch in the elastic half infinite space is established. The relationship between the normal stress distribution, the friction torque and the adhesion radius and the twist angle is obtained by using Maple to write the calculation program. A real time observation device for the interface between the friction and the torsion is developed, and the PMMA and 4 are carried out. The friction and wear test of the 5# steel end is tested. By using a high-speed micro camera, the real time observation and analysis of the adhesion and slip areas of the friction interface are observed. The exact dynamic relationship between the real time wear morphology and the cycle times of the interface under different loads and twists is obtained. Based on the test data of MC nylon and PTFE, the friction torque twist angle (T- theta) curve is obtained. The correctness of the torsional friction model is further verified by the line and the stable friction torque. The conclusions are as follows:
1, the normal stress of the contact center is minimal, and the normal stress is increased rapidly at the angle of the flat bottom punch. The stress concentration is rapidly increased. The shear modulus, the twist angle, the friction coefficient and the normal force change the size of the adhesive radius synthetically, that is, the contact state of the torsion is determined, which is nonlinear with the adhesion radius. The friction torque increases with the adhesive radius as a whole, until the maximum value near the edge, then slightly decreases.
2, the T- theta curve of the PMMA-45# steel mating pair increases with the angular displacement from a straight line to an ellipse and turns to a parallelogram. Under the same angular displacement, the adhesion radius increases with the increase of the normal load. At the torsion angle of 0.1 degrees, the theoretical adhesion radius of PMMA at the normal load 83N, 123N and 163N is 5mm, indicating the torsion boundary. When the surface is in full adhesion, the measured adhesion radius is 3.8mm, 4mm and 4.15mm. are 0.25 degrees at the torsion angle. The theoretical adhesion radius of PMMA under the normal load 83N, 123N and 163N are 1.48mm, 3.88mm and 5mm respectively. When the torque angle is 0.5 degrees, the theoretical adhesion radius of PMMA under normal load 83N, 123N and 163N is 0.074mm, 0.5mm and 1.2mm respectively. The measured adhesion radius is 0,0 and 0.5mm, the whole interface is in the state of complete slip. The measured viscosity is close to the theoretical value, that is, the relationship between the adhesion radius and the twist angle verifies the end face twisting. The correctness of the model.
3, the surface torsion interface damage occurs first at the edge of the contact interface, and the partial slip region shows the scratch morphology, and the complete slip region shows a Silver Stripe damage. With the increase of the number of cycles, the damage of the viscous / sliding boundary is gradually increased and diffused to the contact center until the circular junction, the contact center still has no damage. In the partial slip zone, viscosity / There is an uneven distribution along the circumferential direction at the slip junction, and the grinding marks are growing along the circumference, gradually expanding along the radial direction, accompanied by slight fine lines (i.e., Silver Stripe) damage. In the complete slip zone, the ripple characteristics of the silver lines are very obvious. The silver striations are produced along the radial direction, and the process of stretching and blurring, and finally leaving plastic flow. Under the same load, the wear volume of PMMA increases slightly with the increase of the angular displacement amplitude, and the PMMA wear volume increases with the increase of the normal load.
4, the torque of MC nylon composite and PTFE decreases sharply to the stable state with the increase of the torque angle. The total torque of the end face increases linearly with the increase of the friction coefficient and the normal load. The torque value in the partial slip state is higher than that of the complete slip state. The actual torque under different angular displacement is similar to that of the calculation curve, revealing the torsion. The dynamic friction model can approximately predict the torque of polymer materials under elastic deformation.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TH117.1

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本文編號：2000865