基于小波包降噪与有限元模型修正的结构损伤识别方法

Structural Damage Identification Method based on Wavelet Packet Denoise and Finite Element Method Model Update

针对模型修正方法进行结构损伤时识别精度易受实测模态噪声干扰的问题,提出一种基于小波包降噪与有限元模型修正的结构损伤识别方法。在损伤识别的每一迭代步中,以结构有限元模型为基准,考虑真实模态与模态噪声在时频域内的差异,以实测模态与有限元模型计算模态的差值为对象进行小波包降噪处理;并利用降噪处理后的模态参数构造模型修正目标函数,进行有限元模型修正,经过修正迭代计算后可识别结构的损伤位置与程度。数值算例表明本文方法可明显提高有限元模型修正方法进行结构损伤识别的鲁棒性。

The accuracy of finite element model update for structural damage identification is easily affected by the noisein the measured modal,so the wavelet packet denoise was introduced to reduce the impact of noise.In each iteration step,the wavelet packet denoising treatment was applied to the difference between measured modal and simulated modal from the finite element model,because the time-frequency characteristic of actual modal is different from noise modal.The modal parameters after denoising were used to construct objective function for modal update,and the optimal question was solved to determine the stiffness in FM model.Finally,the stiffness change can indicate the damage position and magnitude.The numerical analysis shows the proposed method can improve the robustness of finite element model update for the structural damage identification.