Detection of matrix cracking an‎d delamination in laminated composite structures using the guided Lamb wave propagation an‎d FBG sensors

11/22/2025 12:00:00 AM

In this research, guided Lamb waves (Lamb Waves) in combination with fiber Bragg grating (FBG) sensors were employed to detect matrix cracking an‎d interlaminar delamination in composite structures. Numerical modeling was carried out using the finite element method (FEM) in Abaqus/Explicit. In the first stage, a baseline model was developed on an isotropic aluminum specimen for validation purposes. Subsequently, a multilayer glass/epoxy composite with a stacking sequence of [0_2,90_6 ]_swas simulated in three conditions: healthy, matrix-cracked, an‎d delaminated. The excitation was performed using the antisymmetric A₀ Lamb mode with a central frequency of 200 kHz under optimized boundary conditions, an‎d the resulting stress an‎d strain fields were exported to the FBG-SIMUL software. The optical response of the FBG sensors was then simulated using the Modified Transfer Matrix Method (MTMM). The results revealed that, in the specimen with matrix cracking, the Bragg wavelength shift (〖Δλ〗_b) increased by approximately 620%, while the Bragg peak width (〖Δλ〗_wv) increased by about 320% compared with the healthy sample. In contrast, for the delaminated specimen, these variations reached approximately 1820% an‎d 600%, respectively. Moreover, the peak-to-valley amplitude of the reflected signal exhibited the highest sensitivity to the presence an‎d severity of damage an‎d was identified as a reliable indicator for distinguishing between different types of defects. For the validation of the numerical model, three complementary approaches were employed. First, an experimental Lamb wave test using piezoelectric (PZT) sensors showed a difference of less than 3% between the measured an‎d simulated wave velocities, confirming the high accuracy of the FEM model. Second, an analytical validation based on Lamb wave equations indicated excellent agreement between the numerical an‎d theoretical stress values, with an error of less than 2%. Finally, results obtained from the semi-analytical Dispersion Calculator software for stress an‎d wave velocity demonstrated strong consistency with the numerical outcomes, with a maximum deviation below 4.5%. Overall, the findings of this study demonstrate that integrating numerical analysis of guided Lamb waves with optical simulation of FBG sensors provides a precise, highly sensitive, an‎d efficient tool for identifying, locating, an‎d quantifying internal damage—particularly interlaminar delamination—in laminated composite structures. This combined approach presents a novel an‎d effective methodology for structural health monitoring (SHM) in advanced composite systems.

امواج هدايت‌شونده لمب , حسگر توري براگ فيبري (FBG) , تشخيص آسيب , ترك زمينه , تورق , شبيه‌سازي عددي , پايش سلامت سازه‌اي (SHM)

Guided Lamb Waves , Fiber Bragg Grating (FBG) Sensors , Damage Detection , Matrix Cracking , Delamination , Numerical Simulation , Structural Health Monitoring (SHM)

Hossein Sabzchi Asl

Prof. Mahmood Mehrdad Shokrieh & Dr. Siavash Kazemirad