Numerical Simulation of Lamb Wave Propagation for Detection of Damage in Composite Structures

With the increasing use of composite materials in the aerospace sector, ensuring their structural integrity is critical. As the industry progresses toward sustainability in material usage, Structural Health Monitoring (SHM) is emerging as a key approach for evaluating structural integrity without causing damage. By continuously monitoring the structural health, the material’s lifecycle can be extended, reducing material waste and supporting more efficient use of resources. This study investigates numerical simulation of Lamb wave propagation using the finite element program LS-DYNA, with the aim of developing a methodology for damage detection in composite structures. The robustness of the methodology is evaluated by analyzing a composite plate under various damage modes and composite material models using different Lamb wave signals. To model the composite plate, thin layers were assigned shells element formulations and stacked to resemble a composite structure. Lamb wave propagation was simulated with the excitation signal defined as a prescribed displacement instead of modelling the sensors used in SHM systems. With a final composite plate model, cracks and delaminations were introduced into the plate, where simulations compared the results from intact and damage plates. The method relies on exciting the Lamb wave signal at a selected excitor node, from which the wave propagates through the plate and the signal data is collected at a receiver node. If a damage is present, the readings at the receiver node will differ from that of an intact plate. The simulations showed that damage such as cracks and delaminations can successfully be detected and localized. The study shows that both amplitude reduction and temporal delay of the wave signal indicates the presence of a damage. The wave interaction with damage suggests potential for characterization of damage modes. Testing various frequencies for the excitation signal demonstrates that higher frequencies are more effective for smaller damages, while lower frequencies are suitable for detecting larger damages. This highlights the importance of selecting frequency based on the criteria for what types and sizes of damage are considered critical for structural integrity.