Guided wave mode selection for inhomogeneous elastic waveguides using frequency domain finite element approach

• Frequency domain finite element method (FDFE) is studied for waves in inhomogeneous waveguides.
• Guided wave mode selection using the approach is addressed.
• An example of mode-selection for inspecting disbond in a quasi-isotropic composite plate is presented.
• Effect of discretization parameters on the solution obtained using FDFE is discussed.

This article describes the use of the frequency domain finite element (FDFE) technique for guided wave mode selection in inhomogeneous waveguides. Problems with Rayleigh–Lamb and Shear-Horizontal mode excitation in isotropic homogeneous plates are first studied to demonstrate the application of the approach. Then, two specific cases of inhomogeneous waveguides are studied using FDFE. Finally, an example of guided wave mode selection for inspecting disbonds in composites is presented. Identification of sensitive and insensitive modes for defect inspection is demonstrated. As the discretization parameters affect the accuracy of the results obtained from FDFE, effect of spatial discretization and the length of the domain used for the spatial fast Fourier transform are studied. Some recommendations with regard to the choice of the above parameters are provided.