The Research On Fretting Fatigue Damage Prediction Methods Of Engine Block-bearing Cap Contact Surface

The engine block and the main bearing cap’s contact surfaces squeeze each other with thelarger bolt preload force when the engine works; easily lead to the occurrence of frettingfatigue between the engine block and the main bearing cap contact surfaces at the outbreak ofalternating pressure and link forces. The research carrying on fretting fatigue crack initiationcharacteristics prediction methods of engine block-bearing cap contact surface. The work andconclusions are as follows:(1) According to the characteristics of the contact, used with a flat-micro-bridge contactmodel plane touching the sample characteristics as analog components, and its structural weredesigned and test load were determined. On this basis, fretting fatigue experimental wasstudied. The results showed that black debris generated with the contact surface, fractureposition located outside the specimen load side of the bridge at the edge of the foot contactsurface.(2) Micro-bridge sample was simulated by using finite element method, the fretting crackinitiation characterization on the contact surface of the sample were predicted by usingfretting fatigue parameters SWT, FS, MSWT, MFS based on critical plane and comprehensivefretting fatigue parameters RUIZ, the predicted results were consistent with the test.(3) Fretting crack initiation characteristic of the body-the main bearing contact surfacewere studied by using the above five methods, the results show that RUIZ parameterprediction method was more consistent with the actual location of the fracture, and increasedpre-bolts clamping force, reduced stiffness and increased body rigidity main bearing caps canhelp reduce effect of fretting fatigue crack initiation.(4) The micro-crack initiation prediction methods were programed by using MATLAB language, and combined with APDL language realizing complete process from the inputparameters to the micro cracks.