Optical Measurement of Preform Impregnation in Resin Transfer Molding

1993 ◽  
Vol 305 ◽  
Author(s):  
Thomas Nowak ◽  
Jung-Hoon Chun
Keyword(s):  
High Performance ◽  
Optical Measurement ◽  
Resin Transfer Molding ◽  
Void Formation ◽  
Woven Fabric ◽  
Void Content ◽  
Trade Off ◽  
Transfer Molding ◽  
Scale Models ◽  
Visualization Experiments

AbstractInfiltration of preforms used to manufacture high-performance, advanced polymer composites can lead to void formation due to inhomogeneities within the preforms. Void formation occurs at three distinct length scales: the fiber, tow and part scales. Flow visualization experiments were used to characterize void formation at the tow and fiber scales. Effects of tow-scale inhomogeneities were studied by varying the warp angle of a woven fabric. Effects of fiber-scale inhomogeneities were studied using scale models of typical tows. The experiments indicate that minimization of void content requires a trade-off between fiberscale and tow-scale void formation.

Optical measurement of voids in situ during infusion of carbon reinforcements

2020 ◽  
pp. 002199832095982
Author(s):  
C Lystrup ◽  
A George ◽  
B Zobell ◽  
K Boster ◽  
C Childs ◽  
...  
Keyword(s):  
Image Analysis ◽  
Carbon Fiber ◽  
High Performance ◽  
Optical Measurement ◽  
Void Formation ◽  
Digital Camera ◽  
Void Content ◽  
Liquid Composite Molding ◽  
Automated Method

Liquid composite molding (LCM) is growing in importance as an alternative to traditional prepreg-autoclave methods for manufacture high-performance composites. The most significant roadblock to industry’s implementation of LCM is the usually higher void content compared with prepreg processing. One tool for reducing void levels in LCM involves optimization of flow velocity, which requires models to be developed to describe void formation at a given velocity. To help solve this problem, the following research illustrates the first known method for optical void measurement in situ during infusion in a carbon fiber reinforcement. Similar to previous studies on glass fiber, this work utilizes fluorescent dye and a digital camera to produce sufficient contrast and resolution for image analysis. Visible bubbles are photographed against the opaque carbon fiber background. An automated method of image analysis is outlined, which was used to analyze 230 images for three different flow orientations of a single fabric, producing the highest amount of experimental data seen so far on in situ void measurement. The resulting data identifies a minimum velocity threshold for minimal macro-void formation. The resultant void characterization framework will better enable optimization of LCM processing for high-performance composites based on carbon reinforcements.

Gate optimization for resin transfer molding in dual-scale porous media: Numerical simulation and experiment measurement

2019 ◽  
Vol 54 (16) ◽  
pp. 2131-2145
Author(s):  
Yutaka Oya ◽  
Tsubasa Matsumiya ◽  
Akira Ito ◽  
Ryosuke Matsuzaki ◽  
Tomonaga Okabe
Keyword(s):  
Resin Transfer Molding ◽  
Void Formation ◽  
Weld Line ◽  
Woven Fabric ◽  
Design Rule ◽  
Self Organizing Maps ◽  
Transfer Molding ◽  
Multi Objective ◽  
Filling Simulation ◽  
Visualization Techniques

For resin transfer molding in a woven fabric, this study developed a novel framework for optimization by combining a multi-objective genetic algorithm and mold-filling simulation including a void-formation model, which gives us not only the spatial distribution of the mesoscopic and microscopic voids but also the correlations between molding characteristics such as fill time, total amount of void, weld line, and wasted resin. Our experiment observation of one-point radial injection successfully captured the anisotropic distribution of mesoscopic voids, which qualitatively validates the simulated result. As a result of multi-objective optimization for an arrangement of two injection positions, we found the trade-off relations of weld line with the other characteristics, which also have positive correlation with each other. Furthermore, visualization techniques such as self-organizing maps and parallel coordinate maps extracted the design rule of the arrangement. For example, a diagonal gate arrangement with an appropriate distance is required for reducing the both total amount of voids, fill time, and wasted resin; however, the total area of the weld line becomes relatively large. Our framework and the knowledge obtained from this study will enable us to determine the appropriate mold design for resin transfer molding.

Modeling and Simulation of Void Formation During the Resin Transfer Molding Process

2012 ◽  
Author(s):  
Aurélie Lebel-Lavacry ◽  
Chung-Hae Park ◽  
Abdelghani Saouab ◽  
Sébastien Guéroult ◽  
Laurent Bizet ◽  
...  
Keyword(s):  
Composite Materials ◽  
Modeling And Simulation ◽  
Capillary Number ◽  
Resin Transfer Molding ◽  
Void Formation ◽  
Experimental Result ◽  
Void Content ◽  
Conductive Liquid ◽  
Transfer Molding ◽  
Air Void

We present modeling and simulation of air void formation in composite materials manufactured by the Resin Transfer Molding (RTM) process. The prediction of air void formation has been an important topic because air voids in composite materials deteriorate the mechanical properties of the part. It has been found by experimental observations that the void content, for a specific preform, can be correlated with capillary number which is the ratio of the viscous force and the surface tension. It is still difficult, however, to predict the void formation without experimental measurement. Moreover, the capillary number may not be the exclusive parameter in practical cases, because the modeling by the capillary number does not work well for large and complex parts. In this context, we propose a mathematical model to predict the air void formation in the channel which is on open gap between fiber tows and inside the fiber tow. Moreover, the void formation in the warp and the weft are modeled separately by considering the tow orientation with respect to the flow direction. We also modeled two other important phenomena, namely air void compression or expansion, and void migration. To validate the model, void content was experimentally measured by injecting an electrically conductive liquid into a preform. The voltage drop was correlated with the air void content considering the air as a non-conducting material. For a unidirectional fabric, a good agreement was obtained between the model prediction and the experimental result.

Research on Fabricating Technology of Three Dimensional Integrated Braided Composite I Beam

2010 ◽  
Vol 136 ◽  
pp. 59-63 ◽  
Author(s):  
X.Y. Pei ◽  
Jia Lu Li
Keyword(s):  
Cross Section ◽  
High Performance ◽  
Research Result ◽  
Three Dimensional ◽  
Void Content ◽  
Braided Composites ◽  
Braided Composite ◽  
Transfer Molding ◽  
3D Braided Composites

In this paper the fabricating technology of three dimensional (3D) integrated braided composite I beam is researched, including: braiding technology of 3D braided I beam preform, the orientation of fiber-tow in the I beam preform, the optimizing of process parameters of resin transfer molding (RTM) for 3D braided composite I beam, and the design of mould for consolidation of composite I beam. The quality of 3D braided composites is good analyzed by ultrasonic A-scan, void content calculation and microscope observation. The research result will provide a good way for designing and fabricating high performance 3D integrated braided composite components with irregular cross section.

scholarly journals In-Situ Void Content Measurements during Resin Transfer Molding

2014 ◽  
Vol 40 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Ryosuke MATSUZAKI ◽  
Daigo SETO ◽  
Akira TODOROKI ◽  
Yoshihiro MIZUTANI
Keyword(s):  
Resin Transfer Molding ◽  
Void Content ◽  
Transfer Molding

Void formation in geometry–anisotropic woven fabrics in resin transfer molding

2013 ◽  
Vol 23 (2) ◽  
pp. 99-114 ◽  
Author(s):  
Ryosuke Matsuzaki ◽  
Daigo Seto ◽  
Akira Todoroki ◽  
Yoshihiro Mizutani
Keyword(s):  
Resin Transfer Molding ◽  
Void Formation ◽  
Woven Fabrics ◽  
Transfer Molding

Formation of Microscopic Voids in Resin Transfer Molded Composites

Materials ◽  
2003 ◽  
Author(s):  
Youssef K. Hamidi ◽  
Levent Aktas ◽  
M. Cengiz Altan
Keyword(s):  
Epoxy Composite ◽  
Resin Transfer Molding ◽  
Microscopic Analysis ◽  
Void Content ◽  
Fiber Preform ◽  
Composite Part ◽  
Transfer Molding ◽  
Average Size ◽  
Induced Defects ◽  
Fiber Preforms

Performance of composite materials usually suffers from process-induced defects such as dry spots or microscopic voids. While effects of void content in molded composites have been studied extensively, knowledge of void morphology and spatial distribution of voids in composites manufactured by resin transfer molding (RTM) remains limited. In this study, through-the-thickness void distribution for a disk-shaped, E-glass/epoxy composite part manufactured by resin transfer molding is investigated. Microscopic image analysis is conducted through-the-thickness of a radial sample obtained from the molded composite disk. Voids are primarily found to concentrate within or adjacent to the fiber preforms. More than 93% of the voids are observed within the preform or in a so-called transition zone, next to a fibrous region. In addition, viod content was found to fluctuate through-the-thickness of the composite. Variation up to 17% of the average viod content of 2.15% is observed through-the-thicknesses of the eight layers studied. Microscopic analysis revealed that average size of voids near the mold surfaces is slightly larger than those located at the interior of the composite. In addition, average size of voids that are located within the fiber preform is observed to be smaller than those located in other regions of the composite. Finally, proximity to the surface is found to have no apparent effect on shape of voids within the composite.

scholarly journals Examination of Void Formation Mechanism by Numerical Analysis

1997 ◽  
Vol 6 (1) ◽  
pp. 096369359700600
Author(s):  
Naoto Ikegawa ◽  
Hiroyuki Hamada ◽  
Zenichiro Maekawa
Keyword(s):  
Finite Element Method ◽  
Porous Medium ◽  
Numerical Analysis ◽  
Formation Mechanism ◽  
Flow Resistance ◽  
Flow Behavior ◽  
Resin Transfer Molding ◽  
Void Formation ◽  
Homogenization Method ◽  
Transfer Molding

In order to analyze flow behavior of resin in the system with porous medium such as fibrous reinforcement for Structural Resin Transfer Molding (SRTM), equivalent viscosity according to a concept of homogenization method was introduced as an index of flow resistance. Numerical analysis using finite element method (FEM) was performed to clarify the void formation mechanism.

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