基于Morlet小波变换的振动特性参数识别

Identification of Vibration Characteristics Parameters Based on Morlet Wavelet Transformation

摘要:

传统的振动系统特性参数识别方法对于非线性、非平稳信号的处理能力差，尤其对于阻尼比的识别精度较低.将Morlet小波变换和随机减量技术相结合识别振动系统的特性参数，首先利用随机减量技术提取振动的自由衰减响应信号，进而由Morlet小波变换对信号进行连续的小波变换处理得到小波能量谱，结合参数识别的基本理论及对时间 幅值坐标面曲线的半对数拟合结果得到振动系统的频率及阻尼比，数值仿真结果表明，提出的方法能有效识别系统的固有频率和阻尼比.将该方法应用于罐车模型流固耦合冲击试验研究，较好地识别出充液工况下振动系统的固有频率和阻尼比.

关键词:Morlet小波变换; 随机减量技术（RDT）; 振动特性参数; 流固耦合冲击试验; 阻尼比

Abstract:

Traditional identification methods of vibration system characteristics are not capable to process nonlinear and non stationary signal,especially the low precision for identifying the damping ratio.An approach to identify the characteristics parameters of vibration system combining on random decrement technique and Morlet wavelet transform is proposed. Firstly, the free decay vibration response signal was extracted by random decrement technique(RDT), and then signal was processed to give a continuous wavelet transform by the Morlet wavelet transform to get wavelet energy spectrum.Combined the basic theory of parameter identification and semi logarithmic and curve fitting result in time frequency coordinate plane, frequency and damping ratio of the vibrating system was got.The numerical simulation result that the proposed method can accurately estimate system natural frequencies and damping ratios. The method was applied for experimental study of tanker liquid solid coupling model, the natural frequency and damping ratio of vibration system structure in loaded water conditions were well identified.

Key words:Morlet wavelet transform; random decrement technique(RDT); vibration characteristics parameters; impact experimental of tanker liquid solid coupling model; damping ratio