基于二次滤波的HHT渡槽模态参数辨识方法  

HHT modal parameter identification for aqueduct based on secondary filtering

作　　者：张建伟[1] 江琦[1] 曹克磊 朱良欢 

机构地区：[1]华北水利水电大学水利学院,郑州450011

出　　处：《农业工程学报》2015年第15期65-71,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金(51009066);河南省高等学校青年骨干教师资助计划(2012GGJS-101);河南省科技攻关(142102310122;132102310320;142300410177)资助

摘　　要：针对大型渡槽安全运行评估问题,提出一种环境激励下基于二次滤波的希尔伯特-黄变换(Hilbert-Huang transform,HHT)模态参数辨识方法。采用小波阈值与经验模态分解(empirical mode decomposition,EMD)结合的二次滤波方法滤除运行环境中强噪声干扰,凸显结构动力特性,有效避免了模态混叠问题;根据奇异熵增量理论确定系统阶数,应用HHT方法辨识降噪后信号,提高辨识准确性和精度。将该方法应用于景泰川二期三泵站输水U型渡槽,辨识正常输水工况下结构前5阶模态参数,建立该渡槽第一跨三维有限元模型,并计算模型同工况下前5阶模态参数,对比模态参数辨识结果与有限元仿真结果。对比结果表明:2种方法计算结果非常接近,最大误差为4.4%。说明基于二次滤波的HHT模态辨识方法能准确高效辨识强噪声背景下结构模态参数,可将该方法推广到大型渡槽结构中,为渡槽安全运行评估和健康在线监测提供新思路,应用前景广阔。In order to improve the accuracy of safe operation assessment for larger aqueduct structure, a valid Hilbert –Huang Transform（HHT） modal parameter identification method based on secondary filtering under ambient excitation was proposed. For the vibration signal of large aqueduct structure, high-frequency white noise and low-frequency noise are often mixed into structure vibration information, which belongs to non-stationary and nonlinear signal in low signal to noise ratio（SNR）. Wavelet threshold method can partially filter out the high-frequency white noise, and Empirical Mode Decomposition（EMD） can be used to obtain a series of intrinsic mode functions from high frequency to low frequency. So the secondary filtering combined wavelet threshold and EMD was used to process vibration signal to achieve a higher precision and a better de-nosing effect. High-frequency white noise and low-frequency water flow noise were filtered out firstly through the secondary filtering, highlighting the useful dominant dynamic characteristics of structure, which reduced the noise interference in a certain extent and avoided the phenomenon of modal frequency mixed effectively during the later modal identification. Then structure system order was determined by theory of singular entropy increment. Finally the modal parameter of large structure was identified through HHT in combination with natural excitation technique（NEx T） to process the de-noised signals, which improved accuracy and precision of modal parameter identification. Taking U-shaped aqueduct of Jintai river pumping irrigation as the research object, we collected the vibration response data under normal working condition. We then used this proposed method to identify vibration response data to achieve the modal parameter of aqueduct structure. According to fluid-solid interactions theory, the three-dimensional finite element model of a cross U-shaped aqueduct structure was constructed through finite element model analysis to obtain the structure modal par

关 键 词：有限元方法 农业工程 供水 HHT 二次滤波 渡槽 模态参数辨识 

分 类 号：TV31[水利工程—水工结构工程] TB53[理学—物理]