Research On Aeronautical Material Interaction Model Of Thermo-fatigue And Creep

Safety is a top priority in the field of civil aviation, aeronautical materials life prediction has always been the focus of aviation scientists. However, there are a lot of aeronautical materials are working in high temperature environment, influenced by both thermal fatigue and creep. The mechanism and effect of fatigue and creep damage is different. It always has deviation between the prediction life and the measured life considering separately fatigue and creep damage, then the study of interaction of thermal fatigue and creep for life prediction is very important.In order to study the life prediction problem for 1Cr18Ni9 Ti austenitic stainless steel influenced both high temperature fatigue and creep, the paper first uses the linear cumulative damage rule at different temperatures to predict lifetime, and discover that the result is different from the measured lifetime. In order to predict life more accurately, the paper introduce the interaction coefficient in life prediction equation to characterize the degree of high-temperature fatigue and creep interaction. Then the interaction coefficients are calculated at different temperatures.To calculate the coefficients of interaction at different temperature, creep experiment is conducted to get their creep rupture time under 200 MPa at 600 ?, 625 ?, 650 ?, 675 ?, 700 ? five temperatures; High temperature fatigue and creep experiment is conducted to get fatigue lifetime at the same five temperatures under trapezoidal wave loading. High temperature fatigue lives are simulated by a professional fatigue analysis software LMS. Based on the three kinds of data mentioned above, high temperature fatigue damage and creep damage are calculated. Combined with the life prediction formula with interaction coefficients, the interaction coefficients were calculated at different temperatures.This paper studies the variation of interaction coefficient at different temperature, and predicts the high temperature fatigue- creep lifetime using the new formula with the interaction coefficient. The result cumulative is more accurate than the prediction life using linear damage method.But in order to characterize the asymmetry effect of high-temperature fatigue and creep, creep damage index and fatigue damage index are introduced to the interaction formula. The interaction model has been amended. After re-calculating the predicted life, the result is closer to the measured life. According the interaction coefficient and damage index, the causes of interaction between high temperature fatigue and creep are analyzedThrough the above studies, the experimental data and ideas as reference are provided to predict the life, since the interaction coefficients are simple to use.