裂纹叶片非线性振动响应理论分析与实验验证

叶片裂纹严重威胁航空安全,已引发数起严重飞行事故。为诊断叶片早期裂纹,对裂纹叶片的非线性振动规律进行了理论和实验研究。建立了裂纹叶片动力学非线性模型,梳理了裂纹尺寸与动力学参数的对应关系,推导得到了非线性振动响应谐波分量功率的耦合量化关系式,结果表明叶片振动分量谐波功率与相邻分量谐波功率以及谐波分量的阶次有关,而且谐波分量相对功率与裂纹深度呈正相关。据此,提出了一种基于谐波分量相对功率的裂纹检测方法。对钢直板叶片进行了模拟仿真和振动台实验,仿真结果和实验结果都表明这种方法可以有效区分裂纹叶片和正常叶片。

Theoretical analysis and experimental verification of nonlinear vibrational response of cracked blade

Blade cracks pose a serious threat to aviation safety and lead to serious aviation accidents. In order to diagnose cracks at the early stage, the nonlinear vibration of cracked blades was investigated theoretically and experimentally. A nonlinear dynamic model was established to link the crack size and the dynamic parameters. A coupling quantification expression of the coupling component power in the nonlinear vibration response was obtained. This response expression indicated that the harmonic element power was determined by the adjacent component power, component order, and positively correlated with the depth of the blade crack. Therefore, based on the relative power of the vibrational components, a crack detection method is proposed. Results of the simulation and the testbed experiment both show that the cracked blades are effectively separated from the normal blades by this method.