A finite element-based heuristic estimation of local preform permeability for resin transfer molding

Uniformity of fabrics significantly affects the resin flow behavior in the resin transfer molding (RTM) process. Due to fabric defects or improper fiber preform preparation/loading, non-uniformity in fabric structure frequently occurs in RTM processing and creates local permeability variations. Such variations often lead to unbalanced resin flow patterns and thus result in defects of finished composite parts. In RTM process modeling, an accurate estimation of the whole field permeability profile of the fiber preform is critical for predicting resin flow pattern correctly. In this article, a finite element-based heuristic computing method is introduced for estimating the in situ whole-field isotropic permeability profile of the preform using a steady flow of gas. Compared with conventional approaches, this method is effective in measuring local permeability variations and applicable to molds with complex 2-D geometries, as well as diverse injection strategies. Several case studies were presented with experimental designs and numerical computations to illustrate the effectiveness and efficiency of the method.