Set-up for unsaturated permeability measurement of LCM reinforcements

Hoto, Rene; Andrés, Javier; Ordeig, I.; García-Manrique, Juan Antonio

doi:10.1063/1.4707634

Cited by 2 publications

(4 citation statements)

References 4 publications

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“…As verified in the next section, the best estimation of the effective permeability is obtained after a sufficiently long time. This is consistent with the measurement methods based on visual flow front observations, where the permeability converges to a final value for sufficiently advanced flow front positions . Finally, we point out that this method is independent of the injection technique (e.g., constant injection pressure or constant flow rate) and no transducer is needed to measure the injection pressure.…”

Section: Theory and Methodologysupporting

confidence: 85%

Characterization of anisotropic permeability from flow front angle measurements

et al. 2015

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Textile permeability is a generally anisotropic material property, which characterizes the ease of establishing a resin flow through the fibrous reinforcement in Liquid composite molding (LCM) processes. Unidirectional injection experiments are commonly performed to determine in‐plane permeability. Effective permeability values have to be measured along three different textile directions to calculate the full in‐plane permeability tensor. This article presents a strategy to reduce the number of the required unidirectional experiments to two or even one by considering the angle that the flow front forms with the measurement direction. The relationship between this flow front angle and the permeability tensor elements was derived theoretically and verified by both simulations and experiments with various textile reinforcements. In addition, two methods were investigated to measure the flow front angle and the effective permeability during the experiments: a standard approach based on visual observations and a new method that relies on three pressure sensors, applicable also in the case of nontransparent tooling. The results show that: (I) the two methods provide consistent measurements and are substantially equivalent; (II) the strategy devised to characterize permeability by measuring the flow front angle is effective and accurate; (III) the proposed procedure allows reducing considerably the time and the material samples required for permeability characterization by unidirectional experiments. POLYM. COMPOS., 37:2037–2052, 2016. © 2015 Society of Plastics Engineers

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Section: Theory and Methodologysupporting

confidence: 85%

Characterization of anisotropic permeability from flow front angle measurements

et al. 2015

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“…Many researchers have been working on the permeability characterization of fabric preforms by using different experimental methods and equipment. Several-separate experiments are more conventional than one-continuous experiments, and they can be conducted either in 1D (linear) [6][7][8][9][10][11][12] or 2D (radial) [13][14][15][16] flow configuration allowing measurement of only one single permeability value or tensor at a certain volume fraction in each experiment. Despite that severalseparate experiments require more intensive labor for mold and specimen preparation, it is more commonly used than one-continuous experiments.…”

Section: Previous Work and Issues About Designmentioning

confidence: 99%

“…Many characterization molds in the literature allow visual monitoring from only one face (top or bottom) which is a transparent lid. [6][7][8]10,[15][16][17]28 However, this configuration can mislead if the flow front races along one mold face and not the other face due to race tracking channels and different surface roughnesses on the two faces, especially when a thick preform is used. An ideal characterization mold should allow monitoring from both top and bottom, and also detect if any void remains in the wetted regions of the specimen.…”

Section: D Flowmentioning

confidence: 99%

“…A press or an equipment similar to a universal compression test machine is preferred to change and control the thickness of the mold cavity during a one-continuous permeability measurement experiment. 8,17,18,20 A powerful press overcomes the need for high compaction force. However, the experimenter needs to be careful to ensure that the mold lids are parallel to each other and thus specimen's thickness is uniform.…”

Section: Equipment and Operationmentioning

confidence: 99%

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A novel mold design for one-continuous permeability measurement of fiber preforms

Yalcinkaya

Sarioglu

Sozer

2015

Journal of Reinforced Plastics and Composites

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One-continuous permeability measurement experiments allow measuring permeability of a fiber preform within a range of fiber volume fractions by conducting a single unsaturated (a.k.a. transient) flow experiment on a dry specimen at an initial thickness, and a set of saturated flow experiments on the wetted specimen by varying the thickness of the mold cavity. This approach allows quicker database construction and reduces the effect of inherent variation of fabric structure caused by inconsistent labor on permeability. In this study, the drawbacks of previous mold designs are eliminated by using appropriate sealing, gap thickness adjustment mechanism and features that allow straightforward and reliable manual operation. Experiments for three different fabric types are conducted and the results are discussed. It is mainly observed that the unsaturated permeability is higher than the saturated permeability.

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Set-up for unsaturated permeability measurement of LCM reinforcements

Cited by 2 publications

References 4 publications

Characterization of anisotropic permeability from flow front angle measurements

Characterization of anisotropic permeability from flow front angle measurements

A novel mold design for one-continuous permeability measurement of fiber preforms

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