Exploring low-velocity impact-induced damage evolution and failure mechanism in composite laminates: Acoustic emission monitoring and finite element simulation

This work combines acoustic emission (AE) testing and finite element (FE) simulation to explore damage evolution and failure mechanisms of carbon/glass interlayer hybrid laminates under low-velocity impact (LVI). In the experimental part, variational mode decomposition (VMD) were adopted to process the AE signals during the impact process, which preliminarily assigned to and identified the AE characteristics corresponding to four typical damage modes (matrix cracking, fiber-matrix debonding, delamination and fiber fracture), and further analyzed their evolutionary sequence and synergistic effect in the impact process. In the numerical part, a refined three-dimensional FE model integrated with the progressive damage model and cohesive elements was established to simulate the damage initiation and propagation behavior under impact load. At 40J and 60J impact energies, matrix cracking initiates first and dominates damage; fiber/matrix debonding and delamination follow sequentially, and fiber fracture appears last. The increase in impact energy significantly aggravates the propagation of delamination damage. The results of numerical simulation and AE analysis mutually verify each other, revealing the core mechanism of low-energy impact damage: the initiation and propagation of intralaminar damage dominated by fiber/matrix in the early stage further induce and dominate the macroscopic failure process dominated by delamination in the later stage.