镍基单晶合金叶片疲劳寿命预测方法研究

研究了3种针对镍基单晶合金各向异性低循环疲劳寿命建模的方法,分别为基于单晶合金弹性模量与晶体取向相关性的方法,与各向异性屈服函数相关的方法和传统滑移系的方法。对基于屈服函数的方法进行了修正以将其应用于单晶合金。利用公开文献中DD3单晶合金的低循环疲劳数据对修正的模型进行了验证,并对采用这3种方法得到的数据进行了比较。结果表明:修正的疲劳寿命模型和基于取向函数的寿命模型的预测结果与试验数据相比基本落在3倍分散带内,而采用基于滑移系的方法所得结果在4倍分散带内。基于屈服函数的修正模型和另外2种模型均可以较好地与3维有限元应力分析直接衔接,便于涡轮叶片结构级的寿命预测。

Fatigue Life Prediction Method of Nickel-based Single Crystal Blade

Three kinds methods of anisotropic low cycle fatigue life for Nickel-based single crystal fatigue were studied, including the method based on elastic modulus of single crystal and crystal orientation relativity, the anisotropic yield function method, and the traditional slip system method. The yield function method was modified to be applied to single crystal. The correction models were validated by low cycle fatigue data of DD3, and the data was contrasted by three methods. The results show that the predicted lives of correction fatigue models and based on the orientation function models are agree with the experimental lives in coefficient of scatter being three, and the predicted lives of the based on slip system models are in coefficient of scatter being four. The correction model based on the yield function and other two models connect with three dimensional finite element stress analysis result well to predict turbine blades life easily.