基于等效等时应力应变曲线的金属材料多工况蠕变分析

Creep Analysis of Metal Materials under MultipleLoading Cases Based on Equivalent Isochronous Stress-Strain Curve

关键词:  航空发动机  涡轮叶片  蠕变  损伤  等时应力应变曲线

Key words:  Aeroengine  Turbine blade  Creep  Damage  Isochronous stress-strain curve

摘要:

为了在工程设计阶段评估涡轮叶片在多工况下的蠕变变形，基于单工况的等时应力应变曲线，提出了一种等效等时应力应变曲线的方法，并与发动机持久试车实例进行了分析比较。结果表明:基于等效等时应力应变曲线方法所计算的涡轮叶片卸载后的残余变形与发动机持久试车结果的相对误差的平均值为15.30%，而通常所采用的基于二维梁理论和基于时间步的三维有限元分析方法所计算的相对误差的平均值分别为45.35%，31.14%，表明该种方法具有较好的工程应用性。

Abstract:

In order to evaluate the creep deformation of turbine blade under multiple loading cases in the engineering design stage， a method of equivalent isochronous stress-strain curve based on the isochronous stress-strain curve corresponding to the single loading case was proposed. The method was carried out and tested by an aeroengine’s long-term trial. The results show that， the average relative error of the residual radial deformation of turbine blade computed by the proposed method is 15.30% with that of the aeroengine’s long-term trial， but for the two other commonly used methods， one is the two-dimensional analysis method based on the beam theory and the other is the three-dimensional FE analysis method based on the time step， the corresponding comparison results are 45.35% and 31.14%， respectively， which indicates the good application of the proposed method.