Elastic Constants Inversion Method for CFRP Plates Based on Multi-Directional Frequency Point Information of Zero Group Velocity

Carbon fiber reinforced polymer (CFRP) plates, characterized by their superior mechanical performance, are extensively employed across the aerospace, wind energy, and shipbuilding industries. The elastic constants of CFRP are key parameters for evaluating its mechanical performance. However, conventional measurement methods are destructive and costly because they require specimen cutting. Although ultrasonic testing provides a nondestructive alternative, its spatial resolution and applicable range remain limited. To address these issues, this study proposes an innovative approach for the inverse identification of the elastic constants of CFRP plates utilizing multi-directional zero group velocity (ZGV) frequency information. An objective function is constructed to quantify the discrepancy between the theoretically calculated and experimentally measured ZGV frequencies, and the particle swarm optimization (PSO) algorithm is employed for multi-parameter optimization. Numerical simulations are conducted on a transversely isotropic CFRP plate to validate the proposed method. The results indicate that the discrepancies among the five retrieved stiffness parameters remain below 1%, demonstrating the high accuracy and strong potential of the proposed approach for the nondestructive evaluation of CFRP plate stiffness properties.