Ultrasonic Inspection with Partial Wave Decomposition for Damage Evaluation

提出了一种基于部分波分解的结构构件超声损伤评估方法。本研究以三维波动理论为基础，分三步进行。利用缺陷散射场的积分表示，采用边界积分方程法对每一步进行数值计算。对于声介质中任意形状的散射体，得到了散射振幅、散射截面和散射场相移的关系。借助散射场的积分表示，明确地写出了这三个物理量的积分表示。它们由散射体的形状、入射波的波数、散射体的边界条件来表示。对相移进行了数值计算，以了解不同形状散射体相移的一般趋势。对弹性动力学和弹性动力学散射截面的推广研究表明，对于弹性动力学的对应物，同样的关系在形式上也是成立的。由于散射振幅、散射截面和相移之间存在明确的关系，因此选取散射截面对弹动力散射场进行量化。给出了缺陷表面弹性动力学散射截面的积分表达式。散射截面与缺陷的形状、入射波的波数、缺陷的边界机制和缺陷的材料性质有关。基于部分波相移的形状识别提出了一种缺陷形状识别的逆方法。该方法基于缺陷散射场相移的积分表示。通过给出相位，对三维散射体的几种缺陷形状进行了数值重建。远场偏移。少

A strategy of partial wave decomposition was introduced for an ultrasonic damage evaluation in a structural component. The study is based on the three dimensional wave theory and has three steps. The integral representation of the scattered field from defects was advantageously utilized and the boundary integral equation method was used for the numerical calculations in every step.1. Integral Representation for Phase Shifts of the Scattered FieldThe relations of scattering amplitude, scattering cross-section, and phase shift of the scattered field were made clear for an arbitrary shape of scatters in an acoustic medium. The integral representations for these three physical quantities were explicitly written down with the help of an integral representation of the scattered field. They are expressed by the shape of scatterer, wave number of the incident wave, boundary condition of the scatterer. The numerical calculation was performed for phase shifts to understand the general tendency o … More f phase shifts for several shapes of scatterers.2. Extension to Elastodynamics and Elastodynamic Scattering Cross-SectionIt was shown that the same relations are formally true for an elastodynamic counterpart. Since there are explicit relations among scattering amplitude, scattering cross-section, and phase shift, the scattering cross-section was selected to quantify for the elastodynamic scattered field. The integral representation of the elastodynamic scattering cross-section was formulated over the surface of the defects. The scattering cross-section is related to the shape of defects, wave number of the incident wave, boundary mechanism of defects, and material property of defects.3. Shape Recognition from Phase Shifts of Partial WavesAn inverse method was proposed for the shape recognition of defects. The method is based on the integral representation of phase shifts of the scattered field from defects. Several shapes of defects were reconstructed numerically for three dimensional scatterers by giving the phase. shifts at the far-field. Less