Optimization of injection flow rate to minimize micro/macro-voids formation in resin transfer molded composites

Ruiz, Édu; Achim, Vincent; Soukane, Sofiane; Trochu, F.; Bréard, Joël

doi:10.1016/j.compscitech.2005.06.013

Cited by 182 publications

(151 citation statements)

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“…The accumulation of voids along the yarn fibres is likely to be due to a similar mechanism, and this is enhanced by the increased tortuosity of the interbundle flow path due to the yarns. Flow in the gaps between layers also experiences shear resistance at the fabric surfaces where voids are likely to adhere, in a similar mechanism by which interbundle voids adhere to tows along the interbundle pathways [1,45,46]. Additionally, the difference in permeability of neighbouring layers results in an uneven flow front which can generate further voids.…”

Section: Mmentioning

confidence: 99%

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High-resolution computed tomography in resin infused woven carbon fibre composites with voids

Sisodia

Garcea

George

et al. 2016

Composites Science and Technology

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Significance of paperRecent efforts in the composites industry towards less-expensive means to produce high-performance parts have often involved optimisation of liquid composite moulding processes such as resin transfer moulding (RTM). The most significant gap in part quality between RTM manufactured parts and traditional autoclave processes is the usually higher void content in the former, arising from the entrapment of bubbles during infusion, and the lower consolidation pressures used during such processes. Many laboratories around the world are working on understanding bubble entrapment and subsequent bubble mobility, so as to optimise RTM processes to reduce the concentration and size of voids. This paper contributes to that understanding with threedimensional examination using CT imaging of the morphology, size, clustering and location of the individual voids in composite parts made with RTM. Most important / novel contributionsThis paper presents visualisation of the voids in a composite part with significantly more statistical information regarding size distribution, orientation and location than has been previously shown in the literature. It also addresses a reinforcement architecture more typical to RTM, an un-balanced weave, than the unidirectional fabrics usually studied in previous work on void formation. Analysing a complex reinforcement along with the enhanced visualisation abilities of the CT-imaging technique allowed novel observations and conclusions regarding voids: 1) As the orientation angle between a reinforcement layer and the resin flow direction increases from parallel to perpendicular, larger voids and a greater number of voids were observed in that layer. This was linked to the resulting greater propensity for fatigue crack propagation between voids in layers transverse to the loading direction. A simple optimisation strategy is thus to infuse in a direction transverse to the expected primary load direction, thus creating the fewest voids in the transverse-to-load direction. 2) Voids accumulate around both the layer interfaces and yarns and are nearly completely absent from the layer thickness between those interfaces and away from yarns. 3) Void distribution follows the orientation of fibres in adjacent layers, suggesting that out-of-plane flow is a significant mechanism in void formation and mobility. 4) Observations 1-3 above all imply that current void formation and mobility models must be expanded from a microscale approach to the laminate scale, in order to focus on out-of-plane bubble movement and yarn bubble entrapment. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT AbstractTomographic imaging using both microfocus radiation and synchrotron radiation was performed to assess the void defects in resin transfer moulded woven carbon fibre composites. The focus of this study is on characterising the void homology (e.g. local void size and spatial distribution) in relation to weave orientation, infusion direction and potential effects on damage formation in tensile loadin...

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Section: Mmentioning

confidence: 99%

“…Process tuning for void minimisation can be supported by inter-and intra-bundle void formation modelling [45]. Further work to expand such models to out-of-plane flow and laminate-scale models of the fibre architecture including woven or stitched fibre architectures could improve these models.…”

Section: Implications Of Findingsmentioning

confidence: 99%

High-resolution computed tomography in resin infused woven carbon fibre composites with voids

Sisodia

Garcea

George

et al. 2016

Composites Science and Technology

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“…The mass flow change is directly affecting the speed of the flow front. It has been shown that there is an optimum of flow front speed which is minimizing the void formation in the composite structure [19][20][21]. Furthermore it is well known that the amount of voids is indirect proportional to mechanical properties of composites [29][30][31].…”

Section: Discussionmentioning

confidence: 99%

“…These stresses can lead to deformation or even debonding of the constituents [18]. It is known that preform impregnation strongly impacts the void formation and therefore the mechanical properties of the composite part [19][20][21]. The aim of this work is to study the influence of processing parameters on hybrid CFRP-steel-components in order to establish optimum processing conditions in order to minimize part deformation and to enhance the mechanical properties of the hybrid part.…”

Section: Introductionmentioning

confidence: 99%

Influence of processing parameters on quality factors of one-shot hybrid structures made by RTM

Hergan

Beter

Stelzer

et al. 2018

Prod. Eng. Res. Devel.

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This paper is dealing with the influence of processing parameters for manufacturing of steel-carbon-fiber-reinforced-plastic (CFRP) hybrid plates by using the one-shot-hybrid resin-transfer-moulding (OSH-RTM) process. A design of experiments study was carried out. The quality of the manufactured parts was quantified by the bending modulus, the apparent interlaminar shear strength (ILSS), the maximum deflection and the density of the CFRP. The following changeable processing parameters were chosen: mould temperature, resin temperature, change in mass flow and maximum injection pressure. It is shown that the mould temperature and the change in mass flow show significant impact on the flexural modulus, density and maximum deflection of the plate while there is no significant impact on the apparent ILSS. Furthermore, the interaction between the mould temperature and resin temperature is having an influence on the flexural modulus and density.

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“…No processo de moldagem por transferência de resina (RTM), por exemplo, a influência dos parâmetros de moldagem na qualidade do compósito final vem sendo investigada. Alguns trabalhos mostram que o auxílio de vácuo durante a injeção da resina minimiza a presença de grandes vazios e parâmetros de operação como a pressão e a velocidade de injeção da resina no processo pode levar à formação de micro ou mesoporos [6,9,10] . Em muitos estudos na literatura, as variáveis de processo são investigadas na busca por parâmetros otimizados, porém poucos se preocupam com o sistema de resina propriamente dito.…”

Section: Introductionunclassified

Efeito de Aditivos Desaerantes nas Características de Compósitos de Epóxi/Fibras de Vidro

2014

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Resumo: A presença de vazios é um importante fator a afetar as propriedades de compósitos poliméricos. Existem várias causas para a formação de vazios, entre elas, o aprisionamento de gás (frequentemente gás úmido) durante o processo de impregnação dos reforços fibrosos com resina e os voláteis gerados durante a formulação da resina. A quantidade de bolhas de ar aprisionadas pode ser, por vezes, reduzida se o sistema de resina é sujeito a um processo de desgaseificação por vácuo ou pelo uso de aditivos químicos especiais. O objetivo deste trabalho é investigar o efeito de um agente desaerante nas propriedades finais de compósitos de resina epóxi moldados pelo processo de RTM utilizando como reforço mantas e tecidos de fibras de vidro. Os compósitos produzidos foram avaliados quanto as suas propriedades de tração, flexão, dureza, short beam e análise dinâmico mecânica (DMA). Em geral, a utilização do aditivo desaerante não provocou alterações significativas nas propriedades mecânicas, tais como resistência e módulo de tração e flexão, as quais são determinadas principalmente pelo tipo e fração volumétrica de fibras. Contudo, os resultados de resistência ao cisalhamento e de dureza mostram um efeito positivo com a inclusão do agente desaerante, levando à melhora na qualidade dos compósitos. Palavras-chave: Compósitos, vazios, sistema epóxi, desaerantes. The Effect of Degassing Agents on the Characteristics of Epoxy/Glass Fiber CompositesAbstract: The presence of voids is an important factor to affect the properties of polymer composites. There are several causes for void formation, such as gas entrapment (most often wet air) during impregnation of the fibrous reinforcement with resin and volatiles arising from the resin system itself. The amount of entrapped air bubbles can sometimes be reduced if the resin system is subjected to a degassing process (e.g. aided by vacuum) or by using special chemical additives. The aim of this research is to investigate the effect of a degassing agent on the final properties of epoxy composites molded by RTM using glass-fiber mats or plain-weave cloths. The produced composites were evaluated under tensile, flexural, hardness and short beam testing, along with dynamical mechanical analysis (DMA). In general, the use of the additive did not ensure significant improvement in those mechanical properties that are primarily determined by the type and content of the fibrous reinforcement, such as tensile and flexural strength and modulus. However, the short beam strength and hardness results showed a positive effect with the inclusion of the additive, leading to better quality composites. Keywords: Composites, voids, epoxy, degassing agents. IntroduçãoA presença de defeitos em compósitos estruturais é um dos pontos críticos para a aplicação destes materiais. Dentre os defeitos que podem ser oriundos da sua produção, pode-se citar regiões ricas em resina ou fibra, fibras distorcidas ou dobradas, presença de contaminantes e vazios, sendo este último de grande preocupação, pois são difíceis...

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Optimization of injection flow rate to minimize micro/macro-voids formation in resin transfer molded composites

Cited by 182 publications

References 12 publications

High-resolution computed tomography in resin infused woven carbon fibre composites with voids

High-resolution computed tomography in resin infused woven carbon fibre composites with voids

Influence of processing parameters on quality factors of one-shot hybrid structures made by RTM

Efeito de Aditivos Desaerantes nas Características de Compósitos de Epóxi/Fibras de Vidro

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