Wavefront estimation in curved-fiber CFRP: A curved Fastest-Path Distribution method for smoothly varying anisotropic material

This study proposes a wavefront estimation method for curved-fiber carbon fiber reinforced plastics (CFRP) with smoothly varying anisotropy, based on a geometrical acoustics framework. The method, termed Fastest-Path Distribution (FPD) Method, predicts ultrasonic wavefronts by computing curved fastest-path trajectories that minimize travel time in anisotropic media. Unlike conventional ray tracing approaches, the proposed method treats anisotropy as a continuous field and represents the wave trajectory using spline-interpolated curves. To validate the method, we conducted optical visualization experiments on a concentric curved-fiber CFRP plate fabricated using 3D printing. A group velocity distribution was experimentally acquired from a unidirectional CFRP specimen and implemented into the simulation. The predicted wavefronts showed good agreement with experimentally observed wavefronts for various source positions, demonstrating that the FPD method enables accurate and efficient wavefront prediction in complex anisotropic media, which supports its applicability to nondestructive testing of curved-fiber CFRP.