Study on the Flexural Damage Evolution and Failure Mechanisms of AFP ‐Manufactured CFRP Laminates Based on X‐Ray Micro‐ CT

ABSTRACT To reveal the effects of internal defects introduced by the automated fiber placement (AFP) process on the flexural performance and damage evolution behavior of CFRP laminates, orthogonally laminated CFRP plates, and CFRP laminates containing artificially introduced gaps were fabricated using AFP. Real internal structural data at different damage stages were obtained by combining three‐point bending tests with X‐ray micro‐computed tomography. Based on these data, a three‐dimensional model incorporating the true internal morphology was established, and defect evolution during damage was quantitatively characterized, while finite element simulations were conducted to investigate stress concentrations around pores and gaps under flexural loading. The results showed that the gap‐containing specimens showed an average maximum load of 834.62 N and an average flexural strength of 243.15 MPa, representing reductions of 30.17% and 31.34%, respectively, compared with the normal lay‐up. The normal lay‐up exhibited a progressive damage sequence from early intralaminar pore expansion to interlaminar damage and late‐stage crack‐dominated failure. In contrast, the gap‐containing specimens had consistently higher defect volume fractions and an earlier crack peak, indicating that the introduced gaps accelerated damage initiation, propagation, and localization.