小波变换时频敏感特性的试验研究  

Experimental study of time-frequency characteristic of wavelet transform

作　　者：朱斌[1] 陈云敏[1] 梁以德[2] 

机构地区：[1]浙江大学土木工程学系,浙江杭州310027 [2]香港城市大学建筑系

出　　处：《浙江大学学报（工学版）》2007年第1期139-143,共5页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(50608062);香港RGC基金资助项目(#CityU1278/03E)

摘　　要：利用小波变换的时频敏感特性,通过试验提出了结构在自由及受迫振动过程中的健康监测及损伤检测方法.在悬臂板与弹簧组成的系统的自由及随机振动过程中,通过烧断连接弹簧与悬臂板的细绳来对系统造成破坏,其中离散小波变换用于识别结构损伤造成的信号奇异性,而连续小波变换则用于排除外界脉冲噪声的影响及确定结构刚度损失的大小.试验结果表明,该方法能有效地监测结构振动过程中的损伤,以及检测结构刚度损失的大小.在结构随机振动试验中,连续小波变换施加在由随机减量法获得的自由衰减信号上,获得了更好的检测效果.所提出的离散小波变换与连续小波变换联合使用的结构健康监测及损伤检测方法可用于结构的在线监测,且无结构建模误差的影响.A health monitoring and damage detection method using the time-frequency characteristic of the wavelet transform was presented based on the results of free vibration and random vibration tests of a system consisting of a cantilever plate and several springs. During vibration of the system, burning out the string connecting the spring to the plate resulted sudden damage to the structure. Discrete wavelet transform was used to recognize the damage at the moment it occurs. Subsequently, the shifts of frequencies and damping ratios were identified by continuous wavelet transform to study the amplitude of stiffness loss of the structure and make sure that the sudden change or impulse in the signal from the discrete wavelet transform was resulted from the damage but not the impulse noise. Test results showed that the proposed method is effective for health monitoring and damage detection of the considered structure. For the random forced vibration, the random decrement technique can be performed on the original signal to obtain the free decaying responses, and then the continuous wavelet transform can be applied to identify the structural pa- rameters. The present method is free of modelling error and can be used for on-line health monitoring.

关 键 词：小波变换 时频特性 健康监测 损伤检测 

分 类 号：TU311[建筑科学—结构工程] O327[理学—一般力学与力学基础]