Process modeling and implicit tracking of moving fronts for three-dimensional thick composites manufacturing

The emerging trends in Resin Transfer Molding (RTM) process technology for composites manufacturing are its applications in the manufacture of complex thick composite structures. Process modeling simulation tools analyzing the three-dimensional flow of resin impregnating the thick fiber preform are instrumental in process optimizations. The true three-dimensional flow field with multiple flow fronts and the merging and diverging fronts involved in the solution of the time progression of the resin inside a mold cavity pose significant challenges and there is a need for efficient, physically accurate algorithms for process simulation studies. In this paper, a new formulation based on the time dependent conservation of resin mass and a pure finite element method are employed to implicitly solve both for the pressure field and track the flow front progression of the resin inside the mold cavity of three-dimensional thick composites. The numerical developments involving the implicit tracking of resin progression flow fronts provide an accurate representation of the physical problem, do not involve the time step restrictions based on Courant condition as in past explicit finite element-control volume associated formulations The discrete time progression of the flow front computed based on the present methodology does not depend on the time step size and the tracked location of the flow front at any discrete time does not depend on the time step size employed to reach that discrete time. The present developments have been validated with simple geometries and then extended to practical applications involving geometrically complex thick composite sections.