Fretting Characteristics Analysis Of Connecting Rod Bushing Of Diesel Engine

The connecting rod is acted upon by the alternating load of piston pin and inertia forceof connecting rod during the running process of engine, The contact surface under the samecontact pressure can produce the different degree of deformation resulting in two contactbodies mutual slip in the contact surface because the material character of connecting rod andbushing is different, it is called fretting. The fretting would not only cause fretting wear, butalso cause fretting fatigue, which can leads to Interference of connecting rod bushing isinsufficient. Insufficient Interference of connecting rod bushing can cause serious damage forengine. So, it is great significance for improving service life of bushing by finding the frettingcharacteristics of connecting rod bushing.Combined with actual working condition of connecting rod and bushing of a certaintype diesel engine, this paper simulates the contact process of the connecting rod and bushingby contact mechanics theory and finite element method for analyzing the frettingcharacteristics of bushing. The specific work is as follows:（1）Access to a large number of literatures of fretting characteristic analysis, this paperexpounds the current status of development of the fretting. The key of research,analysis methods and the problems that need to be solved of this paper are decided.(2) This paper summarizes structure and classification of the connecting rod bushing.On the basis of the elastic contact theory, this paper analyses the commonly ball andplane contact model to get the theory resolution method of key parameters offretting.（3）This paper expounds finite element theory and algorithm of the contact problem. Onehalf of the solid model of connecting rod, bushings and piston pin are established,and the boundary conditions of model are ascertained. This paper analyzes thechanging regularity of the comprehensive stress and deformation of connecting rod and bushing under different amount of interference of bushing in the detonationpressure moment.(4) Firstly, the fretting characteristic of bushing is analyzed under different connectingrod angles when the amount of interference of bushing is 0.05mm. According toanalysis, the key parameters of bushing fretting are the largest in the detonationpressure moment. And then the fretting characteristic of bushing is analyzed underdifferent amounts of interference of bushing in the detonation pressure moment.Finally, the fretting characteristic of bushing is analyzed under different frictioncoefficients when the amount of interference of bushing is 0.05mm. According tothe above analysis result, the law of fretting key parameters of bushing issummarized under different connecting rod angles, amounts of interference ofbushing and friction coefficients. Combined with the fretting characteristic ofbushing, some measures about slowing fretting wear of bushing are proposed.The results show that the fretting of bushing is most serious in the detonation pressuremoment. Along with the increase of amounts of interference, contact pressure, friction stressand frictional work of bushing show increasing trends, but fretting amplitude shows reducingtrend. With the decrease of the friction coefficient, bushing contact pressure changes a little,friction stress and frictional work show reducing trends, but fretting amplitude showsincreasing trend.