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.

Formation of Microscopic Voids in Resin Transfer Molded Composites

2004 ◽  
Vol 126 (4) ◽  
pp. 420-426 ◽  
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 and 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 found to concentrate primarily 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, void content was found to fluctuate through-the-thickness of the composite. Variation up to 17% of the average void 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 Prediction of Defect Formation during Resin Impregnation Process through a Multi-Layered Fiber Preform in Resin Transfer Molding by a Proposed Analytical Model

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2055 ◽  
Author(s):  
Dong Seong ◽  
Shino Kim ◽  
Doojin Lee ◽  
Jin Yi ◽  
Sang Kim ◽  
...  
Keyword(s):  
Defect Formation ◽  
Resin Transfer Molding ◽  
Compressive Behavior ◽  
Fiber Preform ◽  
Transfer Molding ◽  
Resin Impregnation ◽  
Reinforced Composite ◽  
Fiber Deformation ◽  
Occurrence Type ◽  
Fiber Preforms

It is very important to predict any defects occurring by undesired fiber deformations to improve production yields of resin transfer molding, which has been widely used for mass production of carbon fiber reinforced composite parts. In this study, a simple and efficient analytic scheme was proposed to predict deformations of a multi-layered fiber preform by comparing the forces applied to the preform in a mold of resin transfer molding. Friction coefficient of dry and wet states, permeability, and compressive behavior of unidirectional (UD) and plain woven (PW) carbon fabrics were measured, which were used to predict deformations of the multi-layered fiber preforms with changing their constitution ratios. The model predicted the occurrence, type, and position of fiber deformation, which agreed with the experimental results of the multi-layered preforms.

scholarly journals Impact and shear properties of carbon fabric/ poly-dicyclopentadiene composites manufactured by vacuum‐assisted resin transfer molding

e-Polymers ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 437-443 ◽  
Author(s):  
Hyeong Min Yoo ◽  
Moo Sun Kim ◽  
Bum Soo Kim ◽  
Dong Jun Kwon ◽  
Sung Woong Choi
Keyword(s):  
Impact Strength ◽  
Volume Fraction ◽  
Epoxy Composite ◽  
Resin Transfer Molding ◽  
Maximum Shear Stress ◽  
Weight Percent ◽  
Fiber Volume ◽  
Shear Properties ◽  
Transfer Molding ◽  
The Impact

AbstractDicyclopentadiene (DCPD) resin has gained popularity owing to its fast curing time and ease of processing with a low viscosity in the monomer state. In the present study, the impact and shear properties of a carbon fiber (CF)/p-DCPD composite were investigated. The CF/p-DCPD composite was manufactured by vacuum-assisted resin transfer molding with CF as the reinforcement and p-DCPD as the resin with a maximum fiber volume fraction of 55 weight percent. Impact and shear properties of the CF/p-DCPD composite were evaluated and compared with those of a CF/Epoxy composite. The maximum shear stress and modulus of the CF/p-DCPD composite were lower than that of the CF/Epoxy composite. However, the CF/p-DCPD composite had higher toughness than that of the CF/Epoxy composite; this indicates that it is tougher and exhibits a more ductile load-displacement response with a lower modulus and larger failure deformation. The impact strength of the CF/p-DCPD composite was about three time that of the CF/Epoxy composite. The higher impact strength of the CF/p-DCPD composite is attributed to the resin characteristics: epoxy resin has a more brittle behavior, and hence, higher energy is required for crack propagation due to fracture.

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

A Numerical Study of Integrated Direct Cure Kinetics Characterization and Control for Resin Transfer Molding (RTM)

Materials ◽  
2005 ◽  
Author(s):  
Kuang-Ting Hsiao
Keyword(s):  
Control System ◽  
Numerical Study ◽  
Resin Transfer Molding ◽  
Cure Kinetics ◽  
Mold Temperature ◽  
Fiber Preform ◽  
Transfer Molding ◽  
Cure Cycle ◽  
Numerical Case Study

In Resin Transfer Molding (RTM), the fiber preform is first placed inside a mold cavity and is subsequently impregnated with liquid resin. After mold filling, the resin starts to cure and bind the fiber preform into a solid composite part. The cure cycle will affect the residual stress built during RTM and must be controlled. Traditionally, the cure cycle control is achieved through three steps: offline resin cure kinetics characterization, offline cure cycle optimization, and mold temperature control. Different from other traditional cure cycle control approaches, this paper presents an investigation to achieve an integrated cure kinetics characterization-control system by combining a newly developed direct cure kinetics characterization method with online cure cycle optimization. A methodology to seamlessly combine these components for a practicable online cure characterization-control system will be presented and demonstrated by a numerical case study. The accuracy and reliability of this methodology will be examined and discussed based on the results of the numerical case study.

Vacuum-assisted resin transfer molding using tackified fiber preforms

2001 ◽  
Vol 22 (6) ◽  
pp. 721-729 ◽  
Author(s):  
Chih-Hsin Shih ◽  
Qingfang Liu ◽  
L. James Lee
Keyword(s):  
Resin Transfer Molding ◽  
Transfer Molding ◽  
Fiber Preforms
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