魏满晖，向建华，刘健，张利敏.材料热衰退下的连杆衬套刚强度特性分析[J].内燃机工程,2020,41(4):39-45.
材料热衰退下的连杆衬套刚强度特性分析
Analysis of Stiffness and Strength Characteristics for Connecting Rod Bushing Under Thermal Decay of Materials
DOI：10.13949/j.cnki.nrjgc.2020.04.005
关键词:热衰退  连杆衬套  力学性能  塑性变形
Key Words:thermal decay  connecting rod bushing  mechanical properties  plastic deformation
基金项目:国家自然科学基金面上项目（51575045）
作者单位
魏满晖，向建华，刘健，张利敏 1.北京理工大学 机械与车辆学院，北京 100081；2.中国北方发动机研究所，天津 300400 
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摘要:为探究衬套材料的高温性能退化对其刚强度产生的影响，从而为衬套失效抑制设计提供依据，开展了典型锡青铜（QSn7-0.2）与铜镍合金（CuNi6Sn6）两种衬套材料在不同温度下的应力应变力学性能试验，并在考虑材料热衰退特性后对某柴油机连杆衬套组合结构的径向变形量、等效应力、过盈接触压力等刚强度特性进行了计算分析。研究结果表明：两种材料的弹性模量、规定非比例延伸强度及抗拉强度均随温度升高而降低；QSn7-0.2在200~250℃时力学性能急剧衰退，CuNi6Sn6在150~200℃时的热衰退较明显，但在数值上仍高于前者或与其接近。此外，仿真结果表明：QSn7-0.2衬套的径向变形量略大于CuNi6Sn6，失圆现象更加严重；QSn7-0.2衬套等效应力整体偏小，且当温度达到300℃时，衬套中过盈接触压力峰值处产生了一定程度的塑性变形，导致该区域过盈接触压力减小。若变形持续发展，则该衬套较CuNi6Sn6更易产生松脱转动等失效状况。由此可得，材料热衰退是导致衬套出现故障的重要原因，且CuNi6Sn6衬套在高温高载下的力学性能更为优异，更不易产生失效问题。
Abstract:In order to study the influence of the performance decay of bushing materials at high temperature on bushing rigidity and strength and provide a basis for the design of suppressing bushing failure, the stress strain mechanical properties of typical tin bronze (QSn7-0.2) and copper nickel alloy (CuNi6Sn6) at different high temperatures were tested, and the radial deformation, equivalent stress and interference contact pressure of a diesel engine connecting rod bushing of the two materials in assembled state were calculated with considering the material thermal decay characteristics. The results showed that the elastic modulus, specified non proportional extension strengths and tensile strengths of both materials decreased with increased temperature. The mechanical properties of QSn7-0.2 declined sharply at 200~250℃, while those of CuNi6Sn6 decreased slightly obvious at 150~200℃, but the values were still higher than or close to those of QSn7-0.2 at the same high temperatures. In addition, the simulation results showed that the radial deformation of QSn7-0.2 bushing was slightly larger than that of CuNi6Sn6, and the out of roundness was more serious. The equivalent stress of QSn7-0.2 bushing was small on the whole, and when temperature reached 300℃, plastic deformation occurred in the area of the busing where the interference contact pressure was the largest, resulting in a slightly lower interference contact pressure in the region. If the deformation continued to develop, the bushing was more prone to loosen or rotate than CuNi6Sn6. It can be concluded that the material thermal decay is an important cause of bushing failure, and the bushing of CuNi6Sn6 has better mechanical properties at high temperature and high load, and a higher resistance to failure.
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