| Turbine disk is a key part of aero-engine. Once failed, it would lead to serious accident. Research on the fatigue life prediction method of turbine disk is very urgent. During work time, turbine disk is exposed to interactive damage factor including complex loading, high-temperature creep and corrosion. Its failure modes include low cycle fatigue failure, oversize deformation, rupture, plate buckling and vibration cracking. Among them all, low cycle fatigue failure happens most frequently and causes most serious results. Scholars of USA, Russia, England and France began their researches in this field early, so up to now, their predicting and evaluating system of fatigue life is rather complete. But in our country, the beginning of researches in this field is relatively late, and there is no complete system for fatigue life predicting and evaluating. At present, researches of life prediction modeling are mostly focused on some part about engineering application, and also for the foundation of complete prediction and evaluating system later.The research of thesis focuses on two aspects, including improving fatigue life prediction model, fatigue life experiment result evaluating are proposed.The aim of the first part is to improve life prediction model. This part consists of two new models, one is based on interference plain approach and the other is based on critical plain approach. They bring in the effect of cyclic additional hardening in different way, thus both of them are available for non-proportional loading.Two methods for dealing with data are discussed. One is scatter factor, which is available for small-scale experiment; its basic idea is to compare the prediction result with parameters which can reflect the character of the test data. The other is to set the parameter of the model as probability distribution. Then Monte-Carlo simulation is used to work out the results. Mixed Weibull distribution is used to fit the results right and estimate the parameters. |
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