基于最大相似性的Lamb波损伤信号分解及试验研究  

Damage signal decomposition of lamb wave and tests based on similarity

作　　者：王建强[1,2] 余龙[2] 张宇[2] 刘鎏[2] 

机构地区：[1]中国飞机强度研究所,西安710065 [2]西北工业大学力学与土木建筑学院,西安710129

出　　处：《振动与冲击》2014年第24期200-204,210,共6页Journal of Vibration and Shock

基　　金：国家自然科学基金项目(50905141);教育部新世纪优秀人才计划(NCET-10-0078);西工大基础研究基金(NPU-FFR-JC20110258)

摘　　要：损伤反射波的准确提取可以使得基于主动Lamb波技术的损伤检测更有效的进行,而边界等结构特征反射波与损伤反射波产生的混叠,是提取损伤反射波的一个重要障碍。针对混叠情况,目前已有的主动Lamb波损伤监测方法大多采用基于参考信号的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。而由于在传感器接收到的Lamb波信号中,直达波之后时间段内的信号并不是任意波形,而应该是由数个反射波组成的,因此只要得到与目标信号最相似的反射波叠加组合,就可以认为成功解读了该目标信号,即相当于得到了损伤反射波。因此,提出一种基于最大相似性的Lamb波损伤信号分解算法。在分析Lamb波传播特性的基础上模拟边界反射波和损伤反射波,然后基于最大相似性原则,通过遗传算法对二者的合成信号的各个参数进行优化,使合成信号与目标信号之间的相似度达到最大。最后,使用Time of Flight(To F)方法对损伤进行了定位。铝板上的试验结果表明,该方法能够准确地提取出与边界反射波混叠的损伤反射波,从而实现对边界附近损伤的检测。It makes damage detection based on lamb wave more effective to extract accurate damage-scattered signals.Meanwhile,one of the key obstacles in the process of extracting damage-scattered signals is that damage-scattered signals are often overlapped with many other reflected signals from structural features,such as,boundaries.To solve the overlapping problem,the baseline subtraction approach which is sensitive to external factors,such as,structure and environment is adopted in many existing methods to obtain damage-scattered waves.Due to the signal after wave incident in damage signals captured by a sensor is not an arbitrary shape wave,but a superposition of several reflected waves,so as long as the superposition of reflected waves which is most similar to the target signal is gained,the target signal is considered to be interpreted successfully,and consequently,the damage-reflected signal is obtained.Therefore,an approach was proposed based on the maximum likelihood for damage signal decomposition.Damage-reflected signals and boundary-reflected signals were simulated on the basis of analyzing Lamb wave propagation characteristics,and then the various parameters of both synthesis of both above signals were optimized with the genetic algorithm based on the similarity index to make the similarity between the synthetic signal and the target one reach the maximum.Finally,the damage was located with Time of Flight （ToF）.The test results on an aluminum plate indicated that the damage-reflected signals can be accurately extracted from the aliasing waves by means of the proposed method.

关 键 词：结构健康监测 LAMB波 损伤反射波 相似性检测 遗传算法 

分 类 号：TB302.5[一般工业技术—材料科学与工程]