高温下发动机涡轮叶片振动疲劳性能测试方法

Testing method for vibration fatigue performance of engine turbine blades at high temperature

针对某型发动机涡轮叶片高温下振动疲劳性能测试方法进行试验研究。搭建了涡轮叶片中值疲劳极限测量试验系统并建立了相应的试验流程,对比分析了涡轮叶片采用振幅和af值(叶片振幅a与第1阶固有频率f的乘积)两种疲劳应力表征方法的离散程度、偏差随温度的变化趋势,并对小子样升降法参数确定过程进行讨论。试验结果显示振幅作为疲劳应力表征方法的离散程度小,而且可通过常温下获得的振幅表征应力的关系去进行高温下的疲劳试验,其表征偏差位于±3%以内。以逐级加载法获得的疲劳极限预估值作为初始应力水平进行小子样升降法,获得该型涡轮叶片某温度下的中值疲劳极限为162.60 MPa,试验数据分散性小。该方法可为其它类型航空发动机叶片或零部件的高温下振动疲劳性能测试提供参考。

Here,testing method for vibration fatigue performance of turbine blades of a certain type engine at high temperature was studied.The test system for measuring median fatigue limit of turbine blades was constructed,and the corresponding testing procedure was established.Dispersion degrees and deviation varying trends with temperature change of two methods using vibration amplitude and af value(the product of blade vibration amplitude a and its first order natural frequency f),respectively to characterize turbine blade fatigue stress were analyzed contrastively,and the parametric determination process of the small subsample lifting-dropping method was discussed.The test results showed that the dispersion degree of taking vibration amplitude as the characterization of fatigue stress is small,and fatigue tests at high temperature could be conducted with the relation between amplitude and characterized stress obtained at room temperature,the characterization deviation is within±3%;the predicted fatigue limit value obtained using the step-by-step loading method is taken as the initial stress level to implement the small subsample lifting-dropping method,and obtain the median fatigue limit of this type engine’s turbine blade at a certain temperature being 162.60 MPa,the dispersion of test data is small;this method can provide a reference for vibration fatigue performance testing of other types aeroengine blades or parts at high temperature.