Damage diagnose imaging methods based on guided waves have been widely developed to depict the position and area of damage in structural health monitoring (SHM). Among them, compact sensor array based imaging methods have been gradually applied with high accuracy, such as phased array imaging, spatial filter imaging, multiple signal classification imaging and so on. However, when the multi-site damage appears nearly, the performance of these methods usually degrades. On one hand, limited to the array aperture, traditional methods cannot distinguish adjacent damage sites. On another hand, some subspace decomposition based methods also fail, suffering from the correlation between scattered array signals from different damage sites. To realize localization of multi-site damage, a novel near-field signal subspace fitting based multi-site damage localization method is proposed in this paper. This method constructs the cost function, which describe the equivalence relation between the signal subspace and array manifold matrix. Then localization of multi-site damage could be realized through multidimensional search for the optimization of cost function. The proposed method is verified on the aluminum panel with 3 damage sites. Experimental results show that the proposed method can realize multi-site damage localization with the angle errors less than 4° and the distance errors less than 35 mm.

基于导波的损伤诊断成像方法已被广泛开发，用于在结构健康监测（SHM）中描绘损伤的位置和区域。其中，基于紧凑传感器阵列的高精度成像方法已逐渐得到应用，如相控阵成像、空间滤波成像、多信号分类成像等。然而，当多站点损坏即将出现时，这些方法的性能通常会下降。一方面，受限于阵列孔径，传统方法无法区分相邻损伤部位。另一方面，一些基于子空间分解的方法也会失败，因为来自不同损伤部位的散射阵列信号之间存在相关性。为了实现多站点损伤定位，提出一种基于近场信号子空间拟合的多站点损伤定位方法。该方法构造了代价函数，描述了信号子空间与阵列流形矩阵之间的等价关系。然后通过多维搜索优化成本函数，实现多部位损伤的定位。该方法在具有 3 个损伤点的铝板上进行了验证。实验结果表明，该方法能够实现多点损伤定位，角度误差小于4°，距离误差小于35 mm。