Experimental characterization of single ply out‐of‐plane permeability through gaseous flow

Abstract

A new approach to measure out‐of‐plane permeability of single ply unidirectional fiber material under tensile load has been investigated. Single ply permeability is an important material parameter in prepreg fabrication processes where the polymer impregnates the fiber reinforcement. Fibers are processed under tension changing the flow behavior of the resin into the porous media. The experimental characterization cell developed for these processes is mounted to a universal testing machine allowing application and continuous variation of the tensile load applied to the fiber sample. The article outlines the setup including the sensing and data acquisition concept, and implements the data reduction procedure based on Darcy's flow in porous media to obtain the transverse permeability as a function of tension loading. Transverse permeability was determined for single glass and carbon fiber tows for a wide range of tensile loading. The smaller diameter carbon tow permeability showed an order smaller permeability compared to glass fibers. In addition, permeability for both materials changed up to two orders as tensile loading was applied. The results can be used to optimize the impregnation behavior of single ply infusion processes. POLYM. COMPOS., 39:3247–3258, 2018. © 2017 Society of Plastics Engineers

Saturated transverse permeability of unidirectional rovings for pultrusion: The effect of microstructural evolution through compaction

“…The experimental practice with this setup is performed by placing a sample consisting of dry fibers between two perforated plates. The test fluid is injected along the through‐thickness direction with a constant flow rate or constant pressure to estimate transverse permeability, 33 also known as TTP 34–36 or out‐of‐plane permeability 14,37 for fabrics. The literature describes that various modifications to the 1D permeability setup have been considered for several different purposes 38–44 .…”

On the design of test molds based on unidirectional saturated flows to measure transverse permeability in liquid composite molding

“…The preform (white in the inset of Figure 1A) is laid out and compressed to the desired fiber volume fraction between two perforated plates (red). The test liquid or gas [ 5,6 ] enters in the mold cavity from a bottom inlet gate, flows through the holes of the lower perforated plate into the fibrous reinforcement, and then out of the sample through the upper perforated plate to leave finally the mold cavity from the outlet gate in the mold cover. The transverse permeability mold and data acquisition system provide experimental data (flow rate , pressure drop , etc.)…”