基于二维线阵和空间滤波器的结构冲击无波速定位方法

Structure Impact Localization Method Based on 2D Linear Array and Spatial Filter Without Wave Velocity

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 widely used in aerospace structures. But invisible damages will occur on them after suffering impact from external objects. Therefore, online structural health monitoring of impact events for composite structures is essential. One of the focuses of current research on impact location is based on piezoelectric sensors （PZTs） and Lamb wave. But the anisotropy of the Lamb wave in a composite structure makes it difficult to use it to locate the position of impact. In this paper, the algorithm of spatial filter for impact location is extended to composite structures and the theory of impact location by the spatial filter without the information of wave velocity is studied. The method of 2D linear PZTs array and spatial filter is proposed for impact location without wave velocity. Firstly, a narrowband Lamb analytic signal is extracted from the broadband impact response signal by a complex Shannon wavelet transform. Then, the angle of impact position relative to the array is calculated by the spatial filter without using the Lamb velocity. Finally, the impact position is calculated by the impact localization formula without velocity. This method is verified on a carbon fiber reinforced polymer. The verifi- cation results show that the method proposed can locate the structure impact without using the Lamb velocity in composite structures, and the error of localization is less than 1 cm.