中文摘要：

本文基于Lamb波和时频分析方法，提出了一种损伤成像方法，对复合材料结构进行在线的连续监测。首先通过高阶板理论建立了Lamb波在各向异性复合材料层板中随传播角度变化的频散关系，得到Lamb波的理论速度分布，为损伤成像提供基准信息；然后采用小波变换对由压电传感元件激励和接收的Lamb波信号在时频域进行分析，提取特征信息，得到散射波的能量分布；在此基础上通过考虑各向异性对Lamb波传播速度的影响，将散射波的能量分布与各个像素点的对比度关联起来，得到损伤的图像，将损伤的情况可视化。同时建立了原型结构健康监测系统，实验研究表明了本文所提出方法的可应用性和有效性。

英文摘要：

This study proposes a damage imaging method using Lamb wave and time-frequency analysis for continuous on-line monitoring of composites. Lamb wave propagating in anisotropic laminates are first analyzed and modeled using higher-order plate theory;and the direction-dependent dispersion relationships and velocity distributions of the waves are established, which provide baseline information for damage imaging. Wavelet transform is applied to the wave signals excitated and sensed by piezoelectric transducers to extract the characteristic information in time-fre- quency domain and to obtain the energy distribution of the scattered waves. Considering the effect of anisotropic property on the velocity distributions of Lamb waves, the image that indicates the damage can be obtained by relating the contrast on individual pixels to the time-dependent energy distribution of scattered waves. Experimental structural health monitoring system was constructed and experimental study results demonstrate the applicability and effectiveness of the proposed method.