基于Lamb波与时频分析的复合材料结构损伤监测和识别

采用将Lamb波和时频分析相结合的方法,对碳纤维增强复合材料层板结构进行在线的连续监测。首先研究Lamb波在复合材料层板结构中的传播问题,利用Mindlin板理论建立了低阶反对称Lamb波在各向异性复合材料层板中随传播角变化的频散关系;然后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,测量出Lamb波在结构中实际传播的飞行时间和群速度,并与理论结果相比较;在此基础上结合理论与实际量测信息,考虑各向异性对Lamb波速度的影响,使用遗传算法确定损伤位置,并估算损伤尺寸。实验研究表明了本文方法的可应用性和有效性。

Damage Detection and Identification for Composites Based on Lamb Waves and Time-Frequency Analysis Method

An online damage detection and identification method is presented using Lamb wave and time-frequency analysis for continuously monitoring of CFRP composites.Fundamental anti-symmetric Lamb wave propagating in anisotropic laminates is modeled using Mindlin plate theory and the direction-dependent dispersion relationships of the waves are established.Wavelet transform is applied to the wave signals actuated and sensed by piezoelectric transducers in the time-frequency domain to extract the characteristic information to measure the actual time-of-flights and wave group velocities propagating in composite laminates and compare them with the results given by the plate theory. Combined with the theoretically computed and actually measured wave velocity,a genetic algorithms is employed to identify the location and the size of the damage by considering the effect of anisotropic properties to the velocities of Lamb waves.The applicability and the effectiveness of the method are demonstrated by experiments.