Foldcore sandwich structures have gained attention for impact-resistant applications due to their high specific mechanical performance and low density. However, their anisotropy, resulting from unidirectional fiber reinforcement, leads to complex mechanical behavior. The combined effect of fiber orientation and core thickness on bending–compression response and failure evolution remains insufficiently characterized. In this study, carbon fiber prepreg foldcore panels were fabricated, and two orthogonal fiber orientations (L and W) as well as core thicknesses (single and double layers) were examined through three-point bending, out-of-plane compression, and post-bending compression tests. A simplified Abaqus model was also developed to support the experimental analysis. Panels with fibers aligned in the L-direction demonstrating superior flexural toughness and delayed failure. Increasing core thickness significantly enhanced bending performance, while its effect on compressive behavior was minimal. Furthermore, post-bending compression tests reveal that even after partial delamination, foldcore structures retain significant compressive strength, indicating their high toughness and structural stability. Numerical simulations confirmed that failure initiates at the core center, with matrix compression dominating for the W orientation and matrix tension for the L orientation.
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