Permeability characterization of sheared carbon fiber textile preform

Abstract

Fabric deformation alters its local permeability characteristics which, in turn, influences the resin infusion process. This work investigates the radial permeability test method of sheared carbon fiber textile reinforcement materials for the purposes of infusion modeling. A novel experimental approach is described, which utilizes a customized Matlab video processing code to track fluid flow and calculate permeability using data from the complete flow field. Results show principal permeability values, K1 and K2, to increase and decrease, respectively, from a near isotropic state as the fabric shear angle increases, yielding a K1/ K2 ratio of 3.74 at the maximum measured shear angle of 40°. Detailed statistical analysis revealed significant error for cases where fewer than 16 measurement directions were used for the permeability calculation, particularly in highly anisotropic samples. POLYM. COMPOS., 39:2287–2298, 2018. © 2016 Society of Plastics Engineers

Effects of post-infusion dwell on vacuum infusion of thermoset composites toughened by thermoplastic interlaminar veils

“…The isotropy of the polyamide veil was unknown prior to testing, and the radial test configuration permitted simultaneous measurement of the two principal permeability values of an anisotropic material. 36,37 A vacuum-driven constant injection pressure experimental setup (Figure 2) was used, as demonstrated by Pierce et al 38,39 A single-ply sample was placed between a bottom tool plate and an upper polycarbonate caul plate (measured cavity thickness of 1.50 AE 0.05 mm), while breather cloth surrounded the sample periphery to establish an even pressure gradient and to maintain cavity thickness. Instead of epoxy resin, olive oil (Kirkland Signature) was infused as a facsimile resin to allow permeability measurement at ambient temperature, as the viscosity of olive oil at room temperature (measured, 0.07 Pa Á s) was consistent with that of the pre-heated RTM6 resin (<0.10 Pa Á s).…”

“…In each experimental run, a radial flow pattern was recorded (1920 Â 1080 px resolution), which was subsequently processed to yield flow front position against flow time data (Figure 6(a)). The permeability value can be obtained using the following isotropic permeability model for constant injection pressure, which is derived from the Laplace equation in polar coordinates, combined with Darcy's law and the continuity equation: 39,49…”

In situ resin age assessment using dielectric analysis and resin cure map for efficient vacuum infusion

“…The simulations assumed a preform comprised of 20 plies of plain weave carbon fiber fabric (areal weight of 193 g/m 2 and 3000 fiber/tow count, part #1530, Fibre Glast). The in-plane permeability of the fabric was measured previously (2.5 Â 10 À11 m 2 , isotropic) using an unsaturated radial flow configuration [29]. Three VI cases were simulated, each with different infusion length: 530 mm (Case A), 600 mm (Case B), and 670 mm (Case C).…”

A multi-physics process model for simulating the manufacture of resin-infused composite aerostructures

“…Olive oil was used as the test fluid, since its standard room temperature viscosity (0.084 Pa.s) was consistent with the viscosity of typical infusion resins (between 0.001 Pa.s and 0.3 Pa.s) [37]. Complete details of the experimental method can be found in previous work [38].…”

“…An in-house MATLAB code was developed to process video footage of the experimental flow front propagation and calculate directional permeability. This code used a statistical approach to define principal permeability values, 1 and 2 , and the principal permeability direction, , with greater confidence [38].…”