Modeling the Manufacturing Process of Thin-Walled Composite Parts by Vacuum Infusion Using Controlled External Pressures

This study considered the molding process of a thin-walled composite structure, imported from a CAD model, with the requirements of the uniformity of the mechanical properties and wall thickness. The developed numerical process model, which includes both the vacuum infusion and post-infusion stages, takes into account the entire complex of processes evolving in a spreading liquid resin, as well as in a porous preform. The controlled process parameters are the temperature and the magnitudes and times of pressure applied to the open surface of the preform and in the vacuum line. The low thickness of the preform walls and the fixation of its inner surface on an open composite mold allow the mechanical part of the problem to be simplified, thus considering only the preform deformation normal to the opened surface, which provides a significant reduction in the simulation time and the ability to effectively optimize the process. The examples associated with the three control modes considered here show that the presented model’s description of the process, with the toolkit for selecting the controlled parameters, eliminates critical situations such as the formation of dry spots, the premature blocking of the vacuum port, or the uneven distribution and insufficient amount of the reinforcing component in the preform. This is due to the appropriately described process dynamics up to the moment of a sharp increase in viscosity and the hardening of the resin. This approach additionally provides access to process parameters that would be inaccessible in a full-scale experiment.