平板叶片非线性振动及疲劳试验

A Study of Nonlinear Vibration and Fatigue Experiment on Square Blade

针对航空发动机压气机叶片掉角故障,提出了一种采用方形平板试件弯扭复合共振开展试验研究的方法,研究了试件非线性振动特性及振动疲劳试验方法。结果表明:叶片模拟试件存在十分复杂的"软硬化并存"非线性特征,对试件开展振动疲劳试验产生重要影响;由于非线性原因振幅具有明显的突跳现象,须使激振频率稍小于曲线峰值频率以保持振动状态的稳定;为了更精准地确定试件裂纹出现节点,在进行疲劳试验时针对试件制定裂纹判定标准;利用制定的裂纹判定标准可成功确定疲劳强度,验证了裂纹判定标准的有效性和可行性。

Aiming at the problem that fracture of blade exists in the aero-engine compressor, this paper proposes a testing methodology by using composite bending-torsional resonance of the square plate testing specimen, and researches on nonlinearity vibration characteristic and vibration fatigue testing method of the specimen. The results show that simulated testing specimens have quite complicated nonlinearity characteristics of softening and hardening to seriously impact on vibration fatigue testing of the specimen. And the phenomenon of amplitude jumping is obvious because of nonlinearity, driving frequency must be slightly less than peak frequency to maintain vibration stability. In order to accurately determine testing specimen crack appearing node, crack criterion is developed. Fatigue strength can be accurately determined by the developed crack criterion, and the test and the verification show that the crack criterion is valid and feasible.