某型发动机风扇叶片的损伤预测与振动分析

Damage Prediction and Vibration Analysis of the Fan Blades of an Engine

为了延长某型发动机风扇叶片的使用寿命,其关键在于如何准确地预测产生疲劳损伤的位置以及发动机工作时可能存在的共振状态,并针对性地采取相应措施。针对这一难点,应用Ansys软件建立叶片模型,并由模态分析测试验证其合理性,在此基础上建立叶片轮盘系统模型,对系统进行静力分析和有预应力的模态分析,成功地预测了叶片产生疲劳损伤的具体位置及系统共振时的形式、临界转速及频率。结果表明:叶片轮盘系统在不同离心转速载荷下等效应力分布方式相近,无明显变化规律,且叶片产生疲劳损伤的位置均为与叶高方向垂直的耳环处,及耳环与橼板的转接处;叶片轮盘系统不可能出现高频激振力引起的共振,可能会发生低频激振力引起的共振情况,且其形式为1阶弯曲振动,转速为8 425.51 r/min,频率为567.29 Hz。

The method to prolong the service lifespan of the fan blades for a certain engine is studied. Themeasurement points and locations of fatigue damage and the resonance state monitoring are predicted, and the relevantmeasures are proposed. The blade model is established through Ansys, and the accuracy is verified by modal analysis andtest. On this basis, model of the wheel and blade system is established. The location of fatigue damage is determined bystatic analysis of the system, and the resonance rotating speed, frequency and type are acquired by modal analysis of theprestressed system. The results show that the distributions of equivalent stress of the system are similar one another underdifferent rotating speed loads. The blade has two critical locations for the fatigue damage, one is on the lug and the other ison the rafter. All the dynamic frequency of the blade-wheel system increases linearly with the increase of the rotating speed.High frequency exciting force cannot lead to resonance for this system, but low frequency exciting force can. And theresonance type is the first order bending vibration, the resonance rotating speed is 8 425.51 r/min, the resonance frequency is567.29 Hz.