Cooperative Deformation Behavior and Its Influence on Wrinkling and Spring-Back in Hot-Stamped Al/CF/PEEK Hybrid Structures

Thermoplastic fiber-metal hybrid structures have attracted increasing attention for lightweight structure applications owing to their high specific strength and damage tolerance. Al/CF/PEEK hybrid components are promising lightweight structures in which the aluminum alloy and CF/PEEK layers undergo coupled deformation during hot stamping. However, how the presence of the aluminum layer modifies the deformation behavior of CF/PEEK in hybrid component forming has not been systematically clarified, particularly regarding its influence on stress–strain response, wrinkling, and subsequent spring-back. This study investigates the deformation behavior of Al/CF/PEEK hybrid V-shaped components through comparative finite element analyses of monolithic aluminum, single-material CF/PEEK, and hybrid structures. The material flow and stress–strain responses of the aluminum and CF/PEEK layers are comparatively analyzed between the monolithic and hybrid configurations, followed by an examination of the wrinkling behavior of CF/PEEK and Al/CF/PEEK and the spring-back responses of monolithic aluminum and the hybrid structure. The results show that, during the hot-stamping stage, the hybrid structure exhibits an S-shaped deformation pattern similar to that of monolithic aluminum, while the aluminum layer constrains the bending and fiber-direction shear deformation of the CF/PEEK layers. This constraint reduces the bending amplitude and shear deformation of CF/PEEK and consequently mitigates wrinkle formation. During the subsequent cooling stage, the differences in the coefficients of thermal expansion, elastic modulus, and crystallization-induced shrinkage between aluminum and CF/PEEK result in different free contraction tendencies. Because the two layers remain mechanically coupled during cooling, this mismatch results in mutual constraint and stress redistribution, leading to a reverse S-shaped residual stress distribution. The resulting residual stress state partially counteracts the spring-back tendency and reduces the spring-back deformation of the hybrid component. These results clarify how aluminum–CF/PEEK interaction modifies the deformation and stress–strain states of the constituent layers and thereby affects wrinkling and spring-back in thermoplastic fiber-metal hybrid structures.