Resin flowing analysis in sandwich laminates under VARTM process

Utilizing a sandwich structure enables FRP assembly to increase bending stiffness and achieve lightweight requirements. Core surfaces are often cut and infused together with fiber laminates in the VARTM process. Nevertheless, resin infusion in the sandwich structure differs from pure fibrous laminates because resin flows rapidly in the grooves and then saturates into the laminates. This research performed sandwich structure infusion experiments under the VARTM process, and defined four resin saturation stages inside the sandwich assembly by observing and explaining the nonlinear experimental flowing fronts. This study also discussed the race-tracking phenomenon of the sandwich structure in detail. This research executed infusion simulations in the 3D sandwich model, including fiber layers and grooves replaced by the circular pipe elements, to compare with the experimental results. Realization of the permeant characteristics in the sandwich structure establishes a base to ensure complete saturation and to analyze the manufacture of large sandwich structures.