Trans‐plane fluid permeability measurement and its applications in liquid composite molding

Abstract

This work discusses tow independent methods to measure and analyze the trans‐plane fjuid permeability of various fiber reinforcements. In the unidirectional flow method, the measured injection pressure and flow rate, together with a one‐dimensional Darcy's law were used to calculate the trans‐plane permeability of fiber mats was independent of flow rate only at low injection pressure. Flow‐induced fiber mat permeability change occurred when the injection pressure exceeded the clamping pressure. Measured permeability in conjunction with a three‐dimensional mold filling computer program was used to simulate the effect of stacking sequence for a combination of different fiber mats on the mold filling pattern. Finally, a method is proposed to simplify the simulation of a three‐dimensional flow through the fiber perform.

An Experimental Assessment of the Saturated Transverse Permeability of Non-crimped New Concept (NC2) Multiaxial Fabrics

“…Another possible source of this non-linearity could be the capillary effects since WEn OO 3 is the only curve to tend downto 0 for decreasing fluid velocities. Eventually, as pointed out for instance by Wu et al for bi-directional stitched fiber mats [17], this could reveal the fabrics consolidation during the flow, most likely to appear for the highest pressures encountered. Further experiments must be carried out on these very heavy glass fibre fabrics.…”

“…A newtonian and incompressible fluid is considered [16], this is justified if the infusion (or more generally the impregnation) takes place before the resin gelification. The porous medium is infinitely rigid, this can be questioned for fabrics where compaction may take place during the flow [17]. The flow must be laminar, this is usually verified for infusion processes.…”

“…But this transient permeability relies usually on optical observations of the flow front [10], quite difficult to achieve on such small distances (of the order of the mm for our N C2) and very seldom purely unidirectional regarding the capillary effects that may drive the flow [23]. To overcome this problem, 3D front tracking are used and transverse permeability is back-calculated from mass conservation expressions combined with Darcy's law [17] [30] [12] [31]. This implies to know the in-plane permeabilities and yields also complex experimental and numerical problems.…”

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

“…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. Some researchers have described the flow using equivalent permeability [16][17][18].…”

“…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.…”