In‐plane anisotropic permeability characterization of deformed woven fabrics by unidirectional injection. Part II: Prediction model and numerical simulations

Abstract

AbstractThe production of polymer composites by resin injection has strongly increased in the recent years for a wide variety of industrial applications. Manufacturing techniques are continuously optimized for higher and faster production cycles and high performance composites are needed to meet industrial requirements. Actually, the reduction of cost and cycle time is the main motivation for liquid composite molding (LCM) process simulation. In this context, the characterization of preform permeability is a key issue in numerical flow analysis. This investigation concerns the experimental study and development of a predictive model for deformed fabric permeability. Such deformations occur when a fabric is draped on a complex surface. A local shear appears. In Part I, an experimental procedure has been described to measure the permeability of deformed fabrics, and a new methodology presented to characterize the in‐plane permeability tensor. In order to implement experimental results in numerical simulation, a permeability model for deformed fabrics is required. Part II develops a predictive model of the principal permeabilities of deformed fabrics and of the orientation of the permeability tensor. Based on unsheared fabric measurements, the model takes into account the unit cell deformation during shear and the initial elliptic flow pattern orientation and anisotropy ratio of undeformed fabrics. Model predictions are corroborated with sheared fabric measurements. Finally, numerical simulations for an automotive body part are carried out to illustrate the effects of fabric shearing on the filling of the composite part. POLYM. COMPOS. 28:812–827, 2007. © 2007 Society of Plastics Engineers.