温度升高会导致材料的力学性能退化，对连杆小头的变形、连杆与衬套的结合状态都会产生较大的影响，可能导致连杆小头轴承润滑不良、衬套松脱等失效现象。针对某柴油机连杆小头摩擦副，本研究利用多体系统动力学及有限元仿真分析了高温状态下材料退化对连杆小头衬套内孔变形的影响，结果表明，温度达到150 ℃后衬套内孔的变形过大，已无法保持与活塞销之间良好的润滑状态。通过有限元计算分析了材料退化对连杆小头与衬套之间接触状态的影响，结果表明温度升高会导致接触面滑移区域扩大、黏着区域减小，衬套更容易发生松脱。通过衬套的压出试验考察了材料退化对连杆与衬套结合力的影响，结果表明，温度由300 ℃降至常温后衬套的结合力锐减，并结合有限元计算，证明了300 ℃时衬套已产生较大的塑性形变，导致降至常温后变形无法消除而容易产生滑移松脱。

The increase of temperature will lead to the material degradation so that the deformation of connecting rod small end and the poor contact state between the connecting rod and the bushing occur, which may cause the poor lubrication of connecting rod small end and the loosening of bushing. The influence of material degradation on the deformation of connecting rod small end bore at high temperature was analyzed by using multibody system dynamics and finite element simulation. The results showed that the deformation of connecting rod small end bore was too large to keep good lubrication with the piston pin beyond 150 ℃. Additionally, the influence of material degradation on the contact state of connecting rod and bushing was analyzed by the finite element simulation. It was found that the increase of temperature would lead to the enlargement of slip zone and the reduction of adhesion zone so as to make the bushing to loosen more easily. Besides, the influence of material degradation on the binding force between connecting rod and bushing was analyzed through the extrusion experiment of bushing. The binding force decreased sharply when the temperature dropped to room temperature from 300 ℃. The finite element simulation also proved that the large plastic deformation had occurred at 300 ℃, which could not recover at room temperature and hence cause the slip and even loosening of bushing easily.