In this paper, elastic wave scattering in hollow pipes with non-axisymmetric and inclined angle defects is studied using finite element (FE) simulations. A comb array transducer is employed in the FE code to excite the pipe in its first longitudinal mode using a 10-cycle sine modulated excitation signal at 120kHz central frequency. Defects with variations in geometrical shapes such as depths, axial and circumferential lengths, and inclined angles are investigated to provide detailed analysis of wave propagation patterns and mode conversions in a 12-in diameter pipe. The influence of each geometrical parameter and also possible newborn modes is studied both in time and wavenumber-frequency domain via circumferential order identification approach and dispersion curves. Results show that the depth of a non-axisymmetric circumferential defect has the minimum influence on the propagating mode while crack’s width can influence the measured longitudinal mode in a sinusoidal pattern which is a function of excitation signal’s wavelength. Further, the propagating mode can exhibit higher contribution of either axisymmetric or non-axisymmetric modes based on the reflection patterns, depending on its angle and axial length.

中文翻译：

---

使用有限元建模分析具有非轴对称和倾斜角缺陷的管道中的波散射

在本文中，使用有限元 (FE) 模拟研究了具有非轴对称和倾斜角缺陷的空心管中的弹性波散射。在 FE 代码中使用梳状阵列换能器，使用 120 的 10 周期正弦调制激励信号以第一纵模激励管道kHz 中心频率。研究了几何形状变化的缺陷，例如深度、轴向和圆周长度以及倾斜角，以提供对 12 英寸直径管道中波传播模式和模式转换的详细分析。通过圆周顺序识别方法和频散曲线在时间和波数频率域研究每个几何参数以及可能的新生模式的影响。结果表明，非轴对称圆周缺陷的深度对传播模式的影响最小，而裂纹宽度对测量的纵向模式的影响呈正弦模式，该模式是激励信号波长的函数。进一步，