Prediction and formation mechanism analysis of wrinkles in discontinuous prepreg tape placement based on dome reinforcement

To predict wrinkle defects in discontinuous prepreg tape placement and elucidate the associated formation mechanisms, this work investigates the dome reinforcement process of composite pressure vessels using Fiber Patch Placement (FPP). A combined experimental and numerical framework is established, with the placement angle treated as the key process variable. First, the material properties of SYM38360/T700 unidirectional thermoset prepreg under processing conditions are characterized through uniaxial tensile, off-axis tensile, cantilever bending, and probe tack tests. Based on the measured parameters, a high-fidelity finite element model is developed by incorporating hybrid shell–membrane elements and viscous contact. Validation at a placement angle of 30° shows good agreement between the predicted wrinkle morphology and the experimental observations. Variable-angle placement experiments are then conducted over a range of 35°-55° with an interval of 5° to evaluate the influence of placement angle on wrinkle formation. The results indicate that wrinkle severity decreases initially and then increases with increasing placement angle, with the best placement quality obtained at 45°. Under this condition, no obvious wrinkles are observed along the fiber direction, whereas only slight out-of-plane bulging appears in the transverse direction. Mechanism analysis reveals that fiber-direction wrinkles are mainly caused by instability induced by abrupt curvature variation in the dome region combined with viscous friction, while transverse wrinkles originate from out-of-plane buckling triggered by transverse compressive stresses developing near the free edges during adaptation to the curved surface.