Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, United States; Integrated System Health Management Laboratory ISHM, National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666, United States.
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, United States; Integrated System Health Management Laboratory ISHM, National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666, United States.
Ultrasonics. 2018 Sep;89:143-154. doi: 10.1016/j.ultras.2018.05.003. Epub 2018 May 16.
Guided wave dispersion curves in isotropic and anisotropic materials are extracted automatically from measured data by Matrix Pencil (MP) method investigating through k-t or x-ω domain with a broadband signal. A piezoelectric wafer emits a broadband excitation, linear chirp signal to generate guided waves in the plate. The propagating waves are measured at discrete locations along the lines for one-dimensional laser Doppler vibrometer (1-D LDV). Measurements are first Fourier transformed into either wavenumber-time k-t domain or space-frequency x-ω domain. MP method is then employed to extract the dispersion curves explicitly associated with different wave modes. In addition, the phase and group velocity are deduced by the relations between wavenumbers and frequencies. In this research, the inspections for dispersion relations on an aluminum plate by MP method from k-t or x-ω domain are demonstrated and compared with two-dimensional Fourier transform (2-D FFT). Other experiments on a thicker aluminum plate for higher modes and a composite plate are analyzed by MP method. Extracted relations of composite plate are confirmed by three-dimensional (3-D) theoretical curves computed numerically. The results explain that the MP method not only shows more accuracy for distinguishing the dispersion curves on isotropic material, but also obtains good agreements with theoretical curves on anisotropic and laminated materials.
各向同性和各向异性材料中的导波频散曲线可通过矩阵束（MP）方法自动从测量数据中提取，该方法通过 k-t 域或 x-ω 域以及宽带信号进行研究。压电片会发出宽带激励、线性啁啾信号，以在板中产生导波。一维激光多普勒测振仪（1-D LDV）可在板上的线的离散位置测量传播波。测量结果首先进行傅里叶变换，转换到波数-时间 k-t 域或空间-频率 x-ω 域。然后使用 MP 方法明确提取与不同波模相关的频散曲线。此外，通过波数和频率之间的关系可以推导出相位和群速度。在这项研究中，通过 MP 方法从 k-t 域或 x-ω 域对铝板的频散关系进行了检验，并与二维傅里叶变换（2-D FFT）进行了比较。还通过 MP 方法对更厚的铝板上的更高阶模态和复合材料板进行了分析。通过数值计算的三维（3-D）理论曲线对复合材料板的提取关系进行了验证。结果表明，MP 方法不仅在区分各向同性材料的频散曲线方面表现出更高的准确性，而且在各向异性和层合材料的理论曲线上也能很好地吻合。
