某型航空发动机涡轮盘低循环疲劳寿命分析

确定发动机零部件的最大应力应变循环是进行零部件寿命研究的重要内容之一.弹塑性有限元分析常用于计算最大应力应变循环,但是由于各种载荷、约束等条件考虑不全面,得到的应力应变循环往往偏大.同时,某些零部件的瞬态温度场是决定其疲劳强度和使用寿命的重要因素,而获得准确的瞬态温度场是非常困难的.文中对某型发动机的高压涡轮盘进行疲劳试验条件下弹塑性有限元分析,对一台涡轮盘的残余应力进行测试,利用稳态温度场计算涡轮盘危险点最大应力应变循环,并根据弹塑性有限元分析和通过残余应力测试得到的最大应力应变循环进行低循环疲劳寿命预测.研究结果表明,弹塑性有限元分析法预测的寿命偏低,由残余应力可以较准确地确定最大应力应变循环.

LOW CYCLE FATIGUE LIFE OF AN AEROENGINE GAS TURBINE DISK

To determine the principal maximal stress-strain cycle of engine components is an important step in research on engine components' life. Elastic-plasticity finite element analysis is used frequently to calculate the maximal stress strain cycle, but the conditions such as various loads and restraints are not considered all-correctly, the stress strain cycle obtains is often too great. The instantaneous temperature field of some components is very important to fatigue strength and low cycle fatigue life, but it is very difficulty to measure the instantaneous temperature field accurately. Elastic-plasticity finite element analysis for a high pressure gas-turbine disk of an aero engine under fatigue test conditions. The residual stress was measured on high pressure disk, and calculated the maximal stress-strain cycle on dangerous location of the disk using the stable temperature field. The low cycle fatigue lives are predicted according to the maximal stress-strain cycles of elasticity-plasticity finite element analysis and the residual stress respectively. The result shows that predicting life by elasticity-plasticity finite element analysis is low and the maximal stress-strain cycle can be calculated accurately by the residual stress method.