【摘要】 研究了基于改进Littlewood-Paley(L-P)小波变换的结构时变模态参数识别方法。用改进的L-P小波对结构动力响应信号进行小波变换,由能量较大的频带所对应的尺度识别结构基本频率及其随时间的变化情况;由某时刻各自由度响应在各阶频率对应尺度上的小波系数的比值识别结构的各阶振型。针对剪切型框架结构,利用识别的频率变化判断结构是否发生损伤以及损伤发生的时间,通过识别损伤前后的一阶振型斜率变化判断损伤发生的位置。该方法不需要激励信息,且有较好的抗噪声能力。更多还原

【Abstract】 The identification of time-variant modal parameters by modified Littlewood-Paley(L-P) wavelet transformation was studied.The responses of a structure subjected to dynamic load were transformed using modified L-P wavelet.The frequency bands with significant energy content were the bands where the natural frequencies are located.The changes of the natural frequencies versus time were determined by the wavelet coefficient graph.The modal shapes were estimated using the ratio of the wavelet coefficients of two degrees of freedom considered at an instant time,corresponding to the frequency band in which the modal frequency lay.The damage of a shear frame structure was detected and the time when the damage occured was estimated with the change of the frequency identified by modified L-P wavelet.The damage location was detected with the change of the slope of the modal shape from the undamaged structure to the damaged one.With this proposed method,structure damage was detected without excitation information,even when there was noise in recorded responses.更多还原