scholarly journals Study of Compaction Properties and Permeability Prediction of Multilayered Quadriaxial Non-Crimp Fabric in Liquid Composite Molding Process

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1525
Author(s):  
Yi Geng ◽  
Jinhua Jiang ◽  
Fangbing Lin ◽  
Huiqi Shao ◽  
Chenglong Zhang ◽  
...  
Keyword(s):  
Cross Sections ◽  
Volume Fraction ◽  
Structural Parameters ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Fiber Volume ◽  
Permeability Enhancement ◽  
Modeling Methodology ◽  
Composite Molding ◽  
High Level

A systematic experimental study was performed to detect the compaction and permeability properties of multilayered biaxial and quadriaxial preforms under vacuum pressure. Compression response on ply level showed that the degree of nesting between quadriaxial NCF was more pronounced and the nesting deformation mechanism was affected by the interaction with stitch yarns. Owing to the meso-channels in the fibrous structure and the nesting between layers, the in-plane permeability of quadriaxial NCF did not follow an inverse proportion relationship with the fiber volume fraction. To predict the in-plane permeability of multilayered quadriaxial NCFs, unit cell models at a high level of geometrical details were built, including local variations in yarn cross-sections and the nesting deformation between layers. Numerical methods were implemented, and the prediction results were in very good agreement with the experimental data. Besides, the major contributing parameters to the enhancement of the in-plane permeabilities were identified by investigating the correlation between permeability and structural parameters of quadriaxial NCF. The modeling methodology and the principles established can be applied to the design of the quadriaxial NCF fabrics, where the permeability enhancement was evidenced.

Optical measurement of local permeability of flax fiber fabrics before liquid composite molding

2018 ◽  
Vol 52 (24) ◽  
pp. 3289-3297 ◽  
Author(s):  
Benoît Cosson
Keyword(s):  
Optical Method ◽  
Fiber Volume Fraction ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Optical Measurement ◽  
Transmission Measurement ◽  
Liquid Composite Molding ◽  
Fiber Volume ◽  
Filling Time ◽  
Composite Molding

Tracking the variability of natural fiber-based fabrics properties, such as local areal weight, fiber volume fraction, and therefore permeability, is crucial to optimize the parts processing of the bio-composites. This paper aims at developing a cost-effective and efficient optical method in order to predict the permeability of flax fabrics used in liquid composite molding processes. This method using an LCD monitor as light source and a reflex camera as a measurement device is based on light transmission measurement through fabric thickness. The raw data given by the camera are gray scale maps, transformed into areal weight maps. FEM software based on levelset method is finally used to highlight the influence of the local variability of the fiber volume fraction, and of the related fabrics porosity and permeability on the mold filling time. The proposed method can be directly implemented on the manufacturing line of the composites. It can be used to optimize, part-to-part, the resin consumption by predicting the resin flow through perform. Interestingly, this novel optical method is auto-calibrated and does not depend on picture resolution.

Effect of Fiber Content on Void Morphology in Resin Transfer Molded E-Glass/Epoxy Composites

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Youssef K. Hamidi ◽  
Sudha Dharmavaram ◽  
Levent Aktas ◽  
M. Cengiz Altan
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Void Formation ◽  
Areal Density ◽  
Fiber Content ◽  
Epoxy Composites ◽  
Formation Mechanisms ◽  
Liquid Composite Molding ◽  
Fiber Volume ◽  
Composite Molding

Effect of fiber volume fraction on occurrence, morphology, and spatial distribution of microvoids in resin transfer molded E-glass/epoxy composites is investigated. Three disk-shaped center-gated composite parts containing 8, 12, and 16 layers of randomly-oriented, E-glass fiber perform are molded, yielding 13.5%, 20.5%, and 27.5% fiber volume fractions. Voids are evaluated by microscopic image analysis of the samples obtained along the radius of these disk-shaped composites. The number of voids is found to decrease moderately with increasing fiber content. Void areal density decreased from 10.5 voids/mm2 to 9.5 voids/mm2 as fiber content is increased from 13.5% to 27.5%. Similarly, void volume fraction decreased from 3.1% to 2.5%. Increasing fiber volume fraction from 13.5% to 27.5% is found to lower the contribution of irregularly-shaped voids from 40% of total voids down to 22.4%. Along the radial direction, combined effects of void formation by mechanical entrapment and void mobility are shown to yield a spatially complex void distribution. However, increasing fiber content is observed to affect the void formation mechanisms as more voids are able to move toward the exit vents during molding. These findings are believed to be applicable not only to resin transfer molding but generally to liquid composite molding processes.

Pressurized Infusion: A New and Improved Liquid Composite Molding Process

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
M. Akif Yalcinkaya ◽  
Gorkem E. Guloglu ◽  
Maya Pishvar ◽  
Mehrad Amirkhosravi ◽  
E. Murat Sozer ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Composite Laminates ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Compaction Pressure ◽  
External Pressure ◽  
Void Content ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Fiber Volume

Vacuum-assisted resin transfer molding (VARTM) has several inherent shortcomings such as long mold filling times, low fiber volume fraction, and high void content in fabricated laminates. These problems in VARTM mainly arise from the limited compaction of the laminate and low resin pressure. Pressurized infusion (PI) molding introduced in this paper overcomes these disadvantages by (i) applying high compaction pressure on the laminate by an external pressure chamber placed on the mold and (ii) increasing the resin pressure by pressurizing the inlet resin reservoir. The effectiveness of PI molding was verified by fabricating composite laminates at various levels of chamber and inlet pressures and investigating the effect of these parameters on the fill time, fiber volume fraction, and void content. Furthermore, spatial distribution of voids was characterized by employing a unique method, which uses a flatbed scanner to capture the high-resolution planar scan of the fabricated laminates. The results revealed that PI molding reduced fill time by 45%, increased fiber volume fraction by 16%, reduced void content by 98%, improved short beam shear (SBS) strength by 14%, and yielded uniform spatial distribution of voids compared to those obtained by conventional VARTM.

Flow-induced deformation of unidirectional carbon fiber preform during the mold filling stage in liquid composite molding process

2017 ◽  
Vol 52 (9) ◽  
pp. 1265-1277 ◽  
Author(s):  
Dong Gi Seong ◽  
Shino Kim ◽  
Moon Kwang Um ◽  
Young Seok Song
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Orientation Angle ◽  
Mold Filling ◽  
Liquid Composite Molding ◽  
Fiber Preform ◽  
Molding Process ◽  
Controllable Factors ◽  
Composite Molding ◽  
Fiber Deformation

Liquid composite molding has been developed as a high-speed process for manufacturing automotive lightweight parts using new equipment that applies a high pressure for mixing and injection. One of the technical issues is the deformation of fiber preform during the process, which causes defects in the size, mechanical properties and appearance of the final products. In this study, two types of deformation in unidirectional fiber preform during the mold filling process are investigated, which are rigid body deformation and local deformation. Three important forces, namely friction, in-mold stiffness of fiber preform and resin flow, are measured to investigate the mechanism of the fiber deformation. The magnitude of the forces was compared at an instant, which influenced the types of fiber deformation. The effects of the orientation angle and the volume fraction of fiber preform and flow rate were investigated to identify controllable factors to prevent undesired deformation during the process.

scholarly journals Formation of Resin-Rich Zones in Composites Processing

2010 ◽  
Vol 123-125 ◽  
pp. 543-546 ◽  
Author(s):  
Chen Song Dong ◽  
Tze Chiun Tsai
Keyword(s):  
Composite Structures ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Liquid Composite Molding ◽  
Fiber Volume ◽  
Factors Affecting ◽  
Composite Molding ◽  
Composites Processing ◽  
Stress And Deformation ◽  
Fiber Preforms

Resin-rich zones are a common phenomenon in liquid composite molding processes. These resin-rich zones cause unwanted residual stress and deformation, and part-to-part variation, and thus they need to be studied in the design of composite structures. An experimental study on the formation of resin-rich zones in angled composite parts is presented in this paper. Two open-channel mold sets were designed and fabricated. Fiber preforms were loaded into these molds and the gaps formed were visually inspected by a microscope. The influences of corner radius, fiber volume fraction, enclosed angle, and stacking sequence were investigated, and significant factors affecting gap thickness were identified by Design of Experiments (DOE). It can be concluded from the experimental results that: 1) Fiber volume fraction is the most significant factor affecting gap thickness. Gap thickness is inversely proportional to fiber volume fraction; 2) Gap thickness is inversely proportional to radius; 3) The gap thickness of unidirectional preforms is larger than that of the cross-ply preforms.

scholarly journals A Conceptional Approach of Resin-Transfer-Molding to Rosin-Sourced Epoxy Matrix Green Composites

Aerospace ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 5
Author(s):  
Sicong Yu ◽  
Xufeng Zhang ◽  
Xiaoling Liu ◽  
Chris Rudd ◽  
Xiaosu Yi
Keyword(s):  
Composite Laminates ◽  
Resin Transfer Molding ◽  
High Viscosity ◽  
Ramie Fiber ◽  
Liquid Composite Molding ◽  
Curing Agent ◽  
Molding Process ◽  
Transfer Molding ◽  
Low Viscosity ◽  
Composite Molding

In this concept-proof study, a preform-based RTM (Resin Transfer Molding) process is presented that is characterized by first pre-loading the solid curing agent onto the preform, and then injecting the liquid nonreactive resin with an intrinsically low viscosity into the mold to infiltrate and wet the pre-loaded preform. The separation of resin and hardener helped to process inherently high viscosity resins in a convenient way. Rosin-sourced, anhydrite-cured epoxies that would normally be regarded as unsuited to liquid composite molding, were thus processed. Rheological tests revealed that by separating the anhydrite curing agent from a formulated RTM resin system, the remaining epoxy liquid had its flowtime extended. C-scan and glass transition temperature tests showed that the preform pre-loaded with anhydrite was fully infiltrated and wetted by the liquid epoxy, and the two components were diffused and dissolved with each other, and finally, well reacted and cured. Composite laminates made via this approach exhibited roughly comparable quality and mechanical properties with prepreg controls via autoclave or compression molding, respectively. These findings were verified for both carbon and ramie fiber composites.

Cure monitoring of the liquid composite molding process using fiber optic sensors

1997 ◽  
Vol 18 (1) ◽  
pp. 133-150 ◽  
Author(s):  
Dara L. Woerdeman ◽  
Julie K. Spoerre ◽  
Kathleen M. Flynn ◽  
Richard S. Parnas
Keyword(s):  
Fiber Optic ◽  
Fiber Optic Sensors ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Cure Monitoring ◽  
Composite Molding

Role of vacuum pressure and port locations on flow front control for liquid composite molding process

2001 ◽  
Vol 22 (5) ◽  
pp. 660-667 ◽  
Author(s):  
Kuang-Ting Hsiao ◽  
John W. Gillespie ◽  
Suresh G. Advani ◽  
Bruce K. Fink
Keyword(s):  
Vacuum Pressure ◽  
Liquid Composite Molding ◽  
Flow Front ◽  
Molding Process ◽  
Composite Molding
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