Ren Yuanqiang, Qiu Lei, Yuan Shenfang, Bao Qiao
Research Center of Structural Health Monitoring and Prognosis, State Key Lab of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Materials (Basel). 2017 May 11;10(5):519. doi: 10.3390/ma10050519.
Structural health monitoring (SHM) of aircraft composite structure is helpful to increase reliability and reduce maintenance costs. Due to the great effectiveness in distinguishing particular guided wave modes and identifying the propagation direction, the spatial-wavenumber filter technique has emerged as an interesting SHM topic. In this paper, a new scanning spatial-wavenumber filter (SSWF) based imaging method for multiple damages is proposed to conduct on-line monitoring of aircraft composite structures. Firstly, an on-line multi-damage SSWF is established, including the fundamental principle of SSWF for multiple damages based on a linear piezoelectric (PZT) sensor array, and a corresponding wavenumber-time imaging mechanism by using the multi-damage scattering signal. Secondly, through combining the on-line multi-damage SSWF and a PZT 2D cross-shaped array, an image-mapping method is proposed to conduct wavenumber synthesis and convert the two wavenumber-time images obtained by the PZT 2D cross-shaped array to an angle-distance image, from which the multiple damages can be directly recognized and located. In the experimental validation, both simulated multi-damage and real multi-damage introduced by repeated impacts are performed on a composite plate structure. The maximum localization error is less than 2 cm, which shows good performance of the multi-damage imaging method. Compared with the existing spatial-wavenumber filter based damage evaluation methods, the proposed method requires no more than the multi-damage scattering signal and can be performed without depending on any wavenumber modeling or measuring. Besides, this method locates multiple damages by imaging instead of the geometric method, which helps to improve the signal-to-noise ratio. Thus, it can be easily applied to on-line multi-damage monitoring of aircraft composite structures.
飞机复合材料结构的结构健康监测（SHM）有助于提高可靠性并降低维护成本。由于在区分特定导波模式和识别传播方向方面具有显著效果，空间波数滤波技术已成为一个有趣的结构健康监测主题。本文提出了一种基于新型扫描空间波数滤波器（SSWF）的多损伤成像方法，用于对飞机复合材料结构进行在线监测。首先，建立了在线多损伤SSWF，包括基于线性压电（PZT）传感器阵列的多损伤SSWF基本原理，以及利用多损伤散射信号的相应波数 - 时间成像机制。其次，通过将在线多损伤SSWF与PZT二维十字形阵列相结合，提出了一种图像映射方法，用于进行波数合成，并将PZT二维十字形阵列获得的两个波数 - 时间图像转换为角度 - 距离图像，从中可以直接识别和定位多损伤。在实验验证中，对复合板结构进行了模拟多损伤和重复冲击引入的实际多损伤实验。最大定位误差小于2厘米，表明多损伤成像方法具有良好的性能。与现有的基于空间波数滤波的损伤评估方法相比，该方法只需要多损伤散射信号，无需依赖任何波数建模或测量即可进行。此外，该方法通过成像而非几何方法定位多损伤，有助于提高信噪比。因此，它可以很容易地应用于飞机复合材料结构的在线多损伤监测。
