Measurement of the Three-Dimensional Permeability of Fiber Preforms Using Embedded Fiber Optic Sensors

Abstract

An experimental technique is described which can be used to measure simultaneously the three principal permeabilities of fiber reforms made of continuous or short fibers. The technique utilizes embedded optical fibers for detecting the position of the liquid front inside the reform. Expressions were derived for calculating the permeabilities from the three-dimensional measurement of the liquid front. Permeabilities measured by the present fiber optic and by the conventional, pressure drop and flow visualization techniques were compared. Good agreements were found between the results of these techniques.

Unified microporomechanical approach for mechanical behavior and permeability of misaligned unidirectional fiber reinforcement

“…• through-thickness flow with constant pressure [11,5] or constant flow rate [12,13]; • three dimensional flows [14][15][16].…”

Advanced Polymer Composite Molding Through Intelligent Process Analysis and Control

“…Among these techniques are optics [24][25][26], ultrasound [27-281, fluorescence [29], calorimetry [30], and DC resistance [31][32][33][34]. All these techniques have to be either embedded or in partial contact with the part to obtain appropriate measurements.…”

Continuous measurement of fiber reinforcement permeability in the thickness direction: Experimental technique and validation

“…(1) where u D is the volume averaged velocity, Q is the flow rate, A is the cross section, K is the permeability, μ is the resin viscosity and P is the resin pressure. Permeability is represented by a three-dimensional tensor as it depends on the direction [5][6].…”

“…The first one is called unsaturated permeability. It is measured by monitoring the flow front advancement as a function of time under a given pressure gradient in the transient resin flow [5][6][7]. The other one is referred as saturated permeability.…”