Design and Compression Failure Mechanisms of Stiffener–Skin Integrated CFRP Stiffened Panel

ABSTRACT Traditional cobonded CFRP stiffened panels are susceptible to premature stiffener–skin debonding under axial compression. This behavior is mainly caused by discontinuous load transfer across adhesive interfaces, leading to interface‐dominated failure. To investigate the influence of integrated manufacturing on load‐transfer behavior and compressive failure mechanisms, cocured integrated CFRP stiffened panels were manufactured using a metal–rubber mold process. Axial compression tests and finite element simulations were conducted to investigate the failure behavior. Results indicate a transition in failure mechanisms from interface‐dominated debonding in traditional panels to structure‐dominated progressive failure in the integrated configuration. This transition is associated with the continuous load‐transfer characteristics introduced by the integrated cocuring architecture, which alters postbuckling stress redistribution. After skin buckling, localized interlaminar damage initiates, while the continuous load transfer promotes compressive fiber failure at the stiffener root. Subsequent damage propagation leads to large‐scale delamination at [0/90] interfaces and to final structural collapse. The integrated structure transforms the failure mechanism from interface‐controlled to structure‐controlled, improving compressive performance. Compared with the traditional configuration, the integrated panel achieves an 11% reduction in structural weight and a 9% increase in compressive load‐carrying capacity. These findings provide insight into failure mechanisms of integrated CFRP stiffened panels and support the design of lightweight, damage‐tolerant composite structures.