PROPAGATION OF GUIDED WAVES IN DAMAGED FIBER REINFORCED POLYMER LAMINATES: NUMERICAL MODELLING

Damage diagnosis in Carbon Fiber Reinforced Polymers (CFRPs) is increasingly crucial due to the rising demand for composite products in several industries. Intralaminar transverse cracks (TCs) are among the most common damages in composite laminates under loading. Hence, early TC detection is vital for reliable structural health monitoring (SHM) and design of CFRP structures. In this study, theTC-induced local wave mode conversion phenomenon is used as a diagnostic tool to identify single TC orientation in a damaged cross-ply CFRP laminate. The TC-induced mode conversion in laminates is modelled using the Finite Element Method (FEM). In the numerical model, Laser-induced Ultrasonic Guided Wave (LUGW) propagation is simulated using an inclined Gaussian laser beam acting on the surface of the laminate. Then, the vertical displacement field of the damaged laminate is analyzed to observe the symmetric (S0) wave mode conversion into antisymmetric (A0) mode. Finally, the 2D wavefield is transformed, using 3D-FFT, into the kx-ky wavenumber domain and analyzed to verify the presence of A0 mode components. This method is applied to three orientations of TC to wave direction, namely: 90°, 30°, and 45°, while undamaged plate is considered as reference. The numerical procedure confirmed its capability in early detection and assessment of TC in CFRP laminates.