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复合材料在航空结构中的应用越来越广,但其遭受外界物体冲击后很容易在内部产生表面不可见损伤,所以对复合材料结构的冲击事件进行在线监测十分必要。基于压电传感器(PTZ)和Lamb波的冲击定位方法是目前的研究热点,但是Lamb波信号在复合材料结构中传播的各向异性给冲击定位带来了困难。本文将空间滤波器算法推广到复合材料结构的冲击监测应用中,研究了与波速无关的空间滤波器冲击定位原理,提出了基于二维线性压电传感器阵列和空间滤波器的结构冲击无波速定位方法。该方法首先采用Shannon连续复数小波变换提取并构建宽带冲击响应信号中的窄带Lamb波解析信号;然后利用波速无关的空间滤波器算法计算出结构冲击相对于各条线性压电传感器阵列的角度;最后使用冲击无波速定位公式计算出结构冲击的位置坐标。在碳纤维层合板上对该方法进行了实验验证。验证结果表明:该方法可以实现对复合材料结构的冲击进行不依赖信号传播速度的定位,定位误差小于1cm。
Composite materials are more and more widely used in aeronautical structures. However, it is easy to produce invisible surface damage when exposed to external objects. Therefore, it is necessary to monitor the impact of composite structures on-line. The impact localization method based on piezoelectric transducer (PTZ) and Lamb wave is the current research hotspot, but the anisotropy of Lamb wave propagating in the composite structure has caused the impact localization. In this paper, the spatial filter algorithm is extended to the application of the impact monitoring of composite structures. The impact localization principle of the spatial filter, which has nothing to do with the wave velocity, is studied. The structural impactless velocity-based positioning based on two-dimensional linear piezoelectric sensor array and spatial filter method. Firstly, the Shannon continuous complex wavelet transform is used to extract and construct the narrow-band Lamb wave analytical signal in the broadband impulse response signal. Then, the wave velocity-independent spatial filter algorithm is used to calculate the structural impact angle with respect to each linear piezoelectric sensor array. Finally, Use impactless wave velocity location formula to calculate the position coordinates of structural impact. The method was verified experimentally on carbon fiber laminates. The verification results show that this method can locate the impact of the composite structure independently of the signal propagation speed, and the positioning error is less than 1 cm.