An Integrated Comprehensive Approach to the Modeling of Resin Transfer Molded Composite Manufactured Net-shaped Parts

摘要

In the process modeling and manufacturing of large geometrically complex structural net-shaped components comprising of fiber-reinforced composite materials by Resin Transfer Molding (RTM), a polymer resin is injected into a mold cavity filled with porous fibrous preforms. The overall success of the manufacturing process depends on the complete impregnation of the fiber preform, by the polymer resin, prevention of polymer gelation during filling, and subsequent avoidance of dry spots. Since the RTM process involves the injection of a cold resin into a heated mold, the associated physics encompasses a moving boundary value problem in conjunction with the multi-disciplinary study of flow/thermal/cure and the subsequent prediction of induced residual stresses inside the mold cavity. Although experimental validations are indispensable, routine manufacture of large complex structural configurations can only be enhanced via effective computational simulations; thus, eliminating costly trial runs and helping designers in the set-up of the manufacturing process. Unlike past efforts [Ngo and Tamma (2000)], this paper describes an in-depth study of the mathematical and computational developments towards the formulation of a fully integrated and comprehensive approach to the modeling of composite manufactured net-shaped parts. The proposed integrated methodology is well suited for applications to practical engineering structural components encountered in the manufacture of complex RTM type composites, and encompasses the following distinguishing features: (i) an implicit pure finite element computational methodology to handle the physics of the moving resin fluid fronts and to overcome the deficiencies of traditional explicit type methods while permitting standard mesh generators to be employed in a straightforward manner, (ii) a multi-scale methodology for predicting the effective constitutive thermophysical properties in the sense of homogenization as related to the permeability tensor for both the virgin and manufactured states, the conductivity tensor, and the elasticity tensor for subsequent use in the integrated flow-thermal/cure-stress formulations, (iii) computational methodology for isothermalon-isothermal considerations, and (iv) preliminary investigations towards the prediction of induced residual stresses in the manufacturing process during post-cure cool down. Overall, the emphasis is placed on mathematical and computational framework leading to applicability for practical situations.