基于小波变换方法的材料小阻尼识别

Damping Identification of Materials Using Wavelet Transform

基于连续小波变换实现了对振动系统的小阻尼识别。该方法基本原理为通过对系统自由衰减响应的小波系数取极大获取小波脊,借助小波脊理论确定系统的各阶模态频率与指数衰减系数iζωni,采取求中值的方法获取衰减稳定段的参数,进而识别出各阶模态阻尼比。与HT法相比,该方法具有较高的稳定性和识别精度,仿真结果表明,无噪声时识别误差为0.023%,30%噪声时识别的最大误差为3.49%,而且研究中发现阻尼识别的误差与信号采样频率相关。进行了LY12材料的阻尼测试试验,根据试验测试数据对阻尼识别的结果,证明了本文方法的有效性。

We identify the small damping of a vibration system using the continuous wavelet transform. In doing so, we obtain wavelet ridges by extracting the maximal wavelet coefficients of the free decrement response of the system. Resorting to the wavelet ridge theory, we determine the modal frequencies and exponential decrement coefficients of various orders. The parameters of decrement-stable sections are obtained through seeking medians, thus identifying the modal damping ratios of various orders. Compared with the Hilbert transform, our identification method is more stable and precise. Simulation results show that its identification error is only 0. 023% without measuring noise and 3.49% with 30% noise measured. We also discover that the error has something to do with the sampling frequency of signals. Finally we do experiments to test the damping of LY12 material and the damping identification results based on the test data prove the effectiveness of our method.