Yu Lingyu, Tian Zhenhua
University of South Carolina, Department of Mechanical Engineering, Columbia, SC, United States.
University of South Carolina, Department of Mechanical Engineering, Columbia, SC, United States.
Ultrasonics. 2016 May;68:43-53. doi: 10.1016/j.ultras.2016.02.001. Epub 2016 Feb 12.
This paper describes phased array beamforming using guided waves in anisotropic composite plates. A generic phased array algorithm is presented, in which direction dependent guided wave parameters and the energy skew effect are considered. This beamforming at an angular direction is achieved based on the classic delay-and-sum principle by applying phase delays to signals received at array elements and adding up the delayed signals. The phase delays are determined with the goal to maximize the array output at the desired direction and minimize it otherwise. For array characterization, the beam pattern of rectangular grid arrays in composite plates is derived. In addition to the beam pattern, the beamforming factor in terms of wavenumber distribution is defined to provide intrinsic explanations for phased array beamforming. The beamforming and damage detection in a composite plate are demonstrated using rectangular grid arrays made by a non-contact scanning laser Doppler vibrometer. Detection images of the composite plate with multiple surface defects at various directions are obtained. The results show that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.
本文描述了在各向异性复合板中使用导波的相控阵波束形成。提出了一种通用的相控阵算法，其中考虑了与方向相关的导波参数和能量倾斜效应。这种在角方向上的波束形成是基于经典的延迟求和原理实现的，即对阵列元件接收到的信号应用相位延迟并将延迟后的信号相加。确定相位延迟的目的是使期望方向上的阵列输出最大化，而在其他方向上使其最小化。为了对阵列进行表征，推导了复合板中矩形网格阵列的波束图。除了波束图，还定义了基于波数分布的波束形成因子，以便为相控阵波束形成提供内在解释。使用非接触扫描激光多普勒振动计制作的矩形网格阵列演示了复合板中的波束形成和损伤检测。获得了复合板在不同方向上具有多个表面缺陷的检测图像。结果表明，导波相控阵方法是一种用于大型复合结构快速检测的潜在有效方法。
