基于压电纤维复合材料的离心叶轮叶片高阶模态测量

为准确获取离心叶轮叶片的高阶振动特性及其模态,利用压电纤维复合材料(Marco fiber composite,MFC)对离心叶轮叶片进行模态测试。设计了MFC激励系统,提出了MFC选型、激励和测点位置的确定方法,研究了不同信号的高阶模态激励效果,并分析了MFC附加质量和刚度对叶片固有频率和模态的影响;结合有限元仿真结果,对比分析了前20阶振动模态的异同。试验结果表明:MFC具有操作简单、重复性好、信噪比高、能够稳定激励出高阶模态等优势,计算模态与测量模态吻合较好,在第6～8阶与第12～15阶之间存在模态密集区域;MFC附加质量和刚度对实验固有频率的影响低于4%。提出的MFC激励方法可用于具有较高固有频率的航空发动机部件的模态测量。

High-order Modal Shape Measurement of Centrifugal Impeller Blade by Using Marco Fiber Composite

In order to obtain the high-order vibration characteristic and mode shape of centrifugal impeller blade accurately, a modal test of a centrifugal impeller blade was conducted by using macro fiber composite (MFC) actuators. The MFC excitation system was designed, the method of MFC type selection, its excitation signal and measuring point position were proposed. The high-order modal excitation effectiveness by using different signals were studied. The influence of MFC added mass and stiffness on the natural frequency and mode shape of the blade were analyzed. Combining with the finite element simulation results, the similarities and differences of the first 20th vibration modes were compared and analyzed. The experimental results show that MFC has the advantages of simple operation, good repeatability, high-signal-to-noise ratio and the ability to excite high-order modes steadily. The calculated mode agrees well with the measured mode, and there are modal densely distributed regions between the 6th-8th and 12th -15th mode. The effect of MFC added mass and stiffness on the experimental natural frequency is less than 4%. The MFC excitation method proposed can be used for modal measurement of aeroengines components with high natural frequency.