In‐plane anisotropic permeability characterization of deformed woven fabrics by unidirectional injection. Part I: Experimental results

Abstract

Because of the increasing use of polymer composites in a wide variety of industrial applications, the manufacturing of complex composite parts has become an important research topic. When a part is manufactured by liquid composite molding (LCM), the reinforcement undergoes a certain amount of deformation after closure and sealing of the mold. In the case of bidirectional woven fabrics, this deformation may significantly affect the resin flow and mold filling because of changes in the values of permeability. Among other considerations that govern the accuracy of numerical simulations of mold filling, it is important to predict the changes of permeability as a function of the local shearing angle of the preform. The resin flow through a fibrous reinforcement is governed by Darcy's law, which states that the fluid flow rate is proportional to the pressure gradient. The shape of the flow front in a point-wise injection through an anisotropic preform is an ellipse. Part I of this article describes a new methodology based on the ellipse equation to derive the in-plane permeability tensor from unidirectional injection experiments in deformed woven fabrics. Part II presents a mathematical model that predicts the principal permeabilities and their orientation for sheared fabrics from the permeability characterization of unsheared fabrics. Unidirectional flow experiments were conducted for a nonstitched, balanced, woven fabric for different shearing angles and fiber volume fractions. This article presents experimental results for deformed and undeformed fabrics obtained by unidirectional flow measurements. A comparison of the proposed characterization methodology with radial flow experiments is also included. POLYM. COMPOS., 28:797-811, 2007.

Experimental determination of the permeability of engineering textiles: Benchmark II

“…However, the most commonly employed method remains the visual monitoring through a transparent mold [14,27]. In order to reduce the scatter and solve statistical equations described in the next section, it was recommended to measure multiple data points during testing.…”

“…As the unidirectional method was chosen, three directions of measurement were necessary to obtain the in-plane ellipse of permeability [14]. Thus, nine institutions were able to carry out these measurements and obtain the permeability ellipse.…”

“…! : unidirectional [14,15] and radial techniques [16,17]. Both methods show advantages and drawbacks.…”

A Prediction Method for In-Plane Permeability and Manufacturing Applications in the VARTM Process

“…Sun [7] and Ni [8] set up a device to visualize the experimental results and measurements of permeability. Wang and Demaria [11][12][13] characterized the in-plane permeability of woven fabrics and proposed a predictive model. Wu [14] and Nedanov [15] researched the trans-plane permeability by theory and experiments to describe 3D permeability of fiber laminates.…”

“…The VARTM simulation involves with parameters, such as the viscosity of resin, the porosity and permeability of fiber laminates. The permeability of FRP laminates is critical in the manufacturing process and numerous researchers have investigated the measurements and analytical models of permeability [7,8] [ [11][12][13][14][15]. Sun [7] and Ni [8] set up a device to visualize the experimental results and measurements of permeability.…”