Analyses of wrinkling mechanisms during forming of multi-layer woven fabric reinforced thermoplastic prepregs

Thermoplastic composites have made their way into the aerospace industry. The forming of prepregs with different ply orientations induces both intra-plane shear and inter-ply slippage behaviors, and the wrinkling risk is strongly increased by improper parameter control. This paper aims to investigate the deformation behavior of prepreg with different ply orientations and of wrinkling mechanisms during forming. A simulation approach of multi-layer thermoplastic prepreg based on a variable friction model with Stribeck curves and a non-orthogonal constitutive model is developed. The relationship between the local fiber deformation and the development of wrinkle defects is revealed. The results show that the balance between the three deformation mechanisms of shear, bending, and slippage behaviors determines the preform quality. Fiber compression induced by inter-ply friction is the main mechanism of wrinkle defects in the forming process of multi-layer thermoplastic prepregs.