高温低周疲劳-蠕变的改进型广义应变能损伤函数方法

Improved Generalized Strain Energy Damage Function Method for High Temperature Low Cycle Fatigue-creep

通过对广义应变能损伤函数(GSEDF)法进行分析,用非弹性应变能表征低周疲劳(LCF)损伤,提出了一种高温低周疲劳-蠕变(LCF-C)寿命预测的改进型GSEDF模型,修正了GSEDF法中的能量参数,使其与工程实际更吻合。所提出的模型具有模型参数少、适用性广和试验数据利用率高等优点,且能综合反映加载方式、保载时间和平均应力的影响。最后,应用该模型对文献试验数据和轮盘用GH4133高温合金在不同温度和应变比(应力比)下的疲劳-蠕变寿命进行了预测,预测结果与实测结果吻合较好,精度明显优于GSEDF模型、SWT模型、应变能频率修正法和塑性应变能密度法。

The generalized strain energy damage function（GSEDF） model for low cycle fatigue-creep（LCF-C） is investigated,and by using the inelastic strain energy as an LCF damage parameter,an improved GSEDF model is proposed for high temperature low cycle fatigue-creep life prediction of high temperature components,which modifies the energy parameter in GSEDF model and is more consistent with the actual engineering than the GSEDF model.The proposed model has the advantage of less parameters in the expression of this model,wide application and higher utilization efficiency of experimental data.Furthermore,this model not only considers the mechanism of loading waveform and hold time,but also the mean stress effects on LCF life.The predicted fatigue lives based on the proposed model are found in good agreement with reported experimental results of aircraft turbine disk alloys GH4133 at different temperatures and strain（stress） ratios.Compared with the GSEDF model,the SWT model,the plastic strain energy density method and the strain energy frequency modified approach,the proposed model is widely applicable and more precise in predicting the life of low cycle fatigue-creep interaction.