"Double-Double" layup thermoplastic laminates and their application potential in automotive structures

The lightweight of automobile structures is an important way to reduce automobile energy consumption and increase cruising range. Although thermosetting matrix composites such as fiber reinforced epoxy have extremely high mechanical properties and lightweight potential, their applications in automotive structures are hindered by high manufacturing energy consumption, maintenance costs, and low design and manufacturing efficiency. A new type of "Double-Double" layup (DD) thermoplastic laminate (±Ф/±Ψ_n) is expected to solve the above problems. This paper analyzed the advantages of DD laminates compared to π/4 laminates (Quad) in lightweight design, and compared the mechanical properties and design analysis processes of laminates with different layup methods (DD, Woven, Quad layups) and different matrix materials (thermosetting epoxy resin, thermoplastic nylon 6). The results showed that the stiffness and strength of high axial stiffness DD laminates in the main load direction were much higher than those of Woven laminates with the same fiber and matrix. The stiffness performance of DD laminates was similar to that of Quad laminates with the same fiber and matrix, but the design efficiency of DD laminates was higher than that of Quad laminates. At the same time, research on DD thermoplastic laminates of carbon fiber reinforced nylon 6 composites (carbon/PA6) found that although the tensile modulus and tensile strength of unidirectional carbon/PA6 were lower than those of unidirectional carbon/epoxy, DD carbon/PA6 laminates could still be designed through the layup so that the stiffness and strength in the main load direction exceeded that of Woven carbon/epoxy laminates. Moreover, themoplastic carbon/PA6 has excellent repairability and recyclability, showing its advantages in automobile structural design.