考虑应力梯度的轮盘疲劳寿命预测

Fatigue life prediction of turbine disk based on stress gradient

考虑应力梯度和尺寸效应对寿命的影响,通过引入应力梯度影响因子,将缺口试件与光滑试件的疲劳寿命相关联,建立了基于Walker平均应力修正的缺口试件寿命预测模型,进而结合三维弹性有限元分析对发动机涡轮盘进行了寿命预测.结果表明:所发展的寿命模型能较好地反映影响疲劳寿命的多种因素,尤其是应力集中对试件疲劳寿命的影响,综合考虑平均应力、应力梯度和尺寸效应的轮盘寿命预测结果更接近试验值,对GH901标准试件和轮盘的疲劳寿命预测结果都在2倍分散带以内.

The effects of stress gradient and dimensional size on fatigue life were investigated.The relationship between the notched specimen and the smooth specimen was correlated by introducing the stress gradient effect factor,and a new model of predicting notched specimen based on the Walker modification for the mean stress effect was established.Three-dimensional elastic finite element（FE） analysis of a turbine disk was carried out to obtain the fatigue parameters for predicting its life.The result shows that this model can well reflect several effects on fatigue life,especially the effect of stress concentration on the fatigue life of specimen.If the mean stress,stress gradient and size effect are considered comprehensively,the prediction result of the disk is closer to the experiment result.This model gives a prediction falling within a scatter of two for both GH901 standard specimen and the disk.