Time-varying Reliability Analysis Based On PDEM Fatigue Damage Model

The main failure form of mechanical parts is fatigue failure.There is great uncertainty in the process of fatigue,so it is of great practical significance to predict and evaluate the reliability of mechanical equipment parts.Based on the ductile dissipative fatigue damage model considering load interactio n,a stress ratio weight factor is introduced to improve the damage evolution equation and a new improved ductile dissipative fatigue damage model is proposed in this paper.The improved toughness dissipation model based on probability density evolution eq uation was solved by using TVD difference scheme with the help of MATLAB software.The time-varying reliability results obtained by the solution were compared with the experimental data points to verify the accuracy of the model.The main work of this paper is as follows:(1)The ductile dissipative fatigue damage model was introduced,a stress ratio weight factor was introduced to improve the damage evolution equation,and a new improved ductile dissipative fatigue damage model was proposed.(2)The main methods of classical structural reliability theory are introduced,and the application scope and defects of these methods are summarized.The probability density evolution theory and the numerical solution method of probability density evolution equation are emphasized,which lays the theoretical foundation for the following.(3)The probability density evolution method is applied to a new improved ductile dissipative fatigue damage accumulation model.Considering the random uncertainty of fatigue life,the fatigue damage state function of materials is constructed according to the improved ductile dissipation fatigue damage accumulation model,and the time-varying reliability curve is obtained by using the probability density evolution method.(4)To solve the time-varying reliability problem of the improved fatigue damage accumulation model based on the probability density evolution method,the fatigue reliability of different materials is solved through two experimental examples.The results of the proposed method are compared with those of PDEM-ML,PDEM-HS and PDEM-Zhao methods.The experimental results of two groups of different materials show that the proposed method has stronger applicability and higher accuracy.In this paper,a new improved ductile diss ipative fatigue damage model is proposed.The time-varying reliability is obtained by solving the improved fatigue damage accumulation model based on the probability density evolution method.The accuracy and applicability of this method are verified by tw o groups of tests.The uncertainty in actual production is considered to predict the fatigue reliability,which has certain value in engineering application.