无参考主动Lamb波结构损伤时反成像监测方法

主动Lamb波损伤监测中的差信号方法获取损伤散射信号容易受到结构和环境等外界因素的影响。针对该问题,提出了无参考信号的损伤成像定位和监测方法;研究了回波式压电阵列的布置方法,并设计采用时间反转窗函数,清除Lamb波监测信号中的直接传播信息和边界反射信号,以截取出内部散射信号;通过控制压电阵列布局、设置窗函数等技术条件,基于时间反转理论中对波源的自适应聚焦原理,直接利用当前状态下的传感信号实现对结构损伤的实时成像、定位与评估,不再需要健康信号作为参考。在玻璃纤维复合材料板上的实验结果表明,该方法能较为准确地实时监测出损伤的位置、范围等特征。

No Baseline Time Reversal Imaging Method for Active Lamb Wave Structural Damage Monitoring

Active Lamb wave damage monitoring methods require a health structural response to act as the baseline. The difference between the damage structural response and the baseline is used to obtain the damage scattering signals in most active Lamb wave damage monitoring methods. Such process will be affected easily by external factors, such as structure and environment variation, etc. This article proposes a no baseline active Lamb wave damage imaging location and monitoring method. Back propagation piezoelectric (PZT) array arrangement method and time reversal window function are purposed to eliminate direct propagation waves and reflections from the boundaries to intercept the inner scattering waves in the structural responses. Based on time reversal theory, current structural responses are used to realize damage location and imaging by suitable piezoelectric array and window function. This method does not need baseline any more. Experiments on a glass fiber reinforced composite board indicate that the location and range of the damage can be expressed well by means of the proposed method.