Numerical study to control the filler distribution in fibrous media during the particle-filled resin transfer molding process

Abstract During the filling process of vacuum assisted resin transfer molding (VARTM), the infusion pressure gradient causes the resin flow and preform thickness variation. Even after the resin infusion discontinues, the resin keeps on flowing until the unnecessary resin is removed. In this study, a one-dimensional flow model coupled to the preform deformation is numerically analyzed to assess the influences of various processing scenarios on the infusion and post-infusion stages. The numerical model is implemented using a finite difference method. Results show that two strategies effectively reduce the filling process. One is to infuse less excess resin and the other is to turn the inlet into the additional vent. For a typical process using a one-sided vent, the theoretically optimum scenario is to infuse the exact required resin volume into the preform. From a practical standpoint, excess resin infusion is inevitable and a robust scenario is proposed by integrating the concept of fully filled preform and two strategies. Additional cases are performed using a vacuum assisted compression RTM (VACRTM) process for comparison purposes. Through the numerical work, a tool for optimization of the VARTM process is provided to reduce the filling process, resin waste and variability in the final composite part.

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Thermal Characterization and Improvement of Curing Stage in Resin Transfer Molding Process

Advances in Computer and Electrical Engineering - Handbook of Research on Recent Developments in Electrical and Mechanical Engineering ◽

10.4018/978-1-7998-0117-7.ch018 ◽

2020 ◽

pp. 479-505

Author(s):

Soukaina Elyoussfi ◽

Aouatif Saad ◽

Adil Echchelh ◽

Mohamed Hattabi

Keyword(s):

Thermal Gradient ◽

Volume Fraction ◽

Numerical Study ◽

Resin Transfer Molding ◽

Thermal Characterization ◽

Differential Method ◽

Temperature Cycle ◽

Molding Process ◽

Transfer Molding ◽

Curing Cycle

Resin Transfer Molding has become one of the most efficient processes to manufacture composite parts. Among the steps in composite part processing is the curing reaction. In the majority of cases, this reaction is of exothermic nature accompanied by a rise in temperature in the laminate. This leads to the appearance of a thermal gradient. This research aims to study the thermal gradient generated. The objective is to minimize the temperature excess in the composite. By means of a one-dimensional numerical study using the finite differential method, we have showed that the energy balance depends not only on the temperature and on the degree of curing but also on several other factors, namely: the volume fraction of the fibres, the temperature cycle, and the reinforcement thickness. Authors have shown in this study the effect of increasing temperature on the optimization of the curing cycle. The chapter also investigated the effect of thickness variation on temperature distribution in the composite. A comparison of the authors' results with literature achievements showed agreement.

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

Aerospace ◽

10.3390/aerospace8010005 ◽

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.

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Development of resin transfer molding process using scaling down strategy

Polymer Composites ◽

10.1002/pc.22821 ◽

2013 ◽

Vol 35 (9) ◽

pp. 1683-1689 ◽

Cited By ~ 5

Author(s):

Raghu Raja Pandiyan Kuppusamy ◽

Swati Neogi

Keyword(s):

Resin Transfer Molding ◽

Molding Process ◽

Transfer Molding ◽

Scaling Down

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Resin transfer molding process: a numerical and experimental investigation

The International Journal of Multiphysics ◽

10.1260/1750-9548.7.2.125 ◽

2013 ◽

Vol 7 (2) ◽

pp. 125-136 ◽

Cited By ~ 9

Author(s):

Iran de Oliveira ◽

Sandro Amico ◽

Jeferson Souza ◽

Antonio de Lima

Keyword(s):

Experimental Investigation ◽

Resin Transfer Molding ◽

Molding Process ◽

Transfer Molding

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A Closed Form Solution for Flow During the Vacuum Assisted Resin Transfer Molding Process

Journal of Manufacturing Science and Engineering ◽

10.1115/1.1285907 ◽

1999 ◽

Vol 122 (3) ◽

pp. 463-475 ◽

Cited By ~ 66

Author(s):

K-T. Hsiao ◽

R. Mathur ◽

S. G. Advani ◽

J. W. Gillespie, ◽

B. K. Fink

Keyword(s):

Closed Form ◽

Scaling Laws ◽

Resin Transfer Molding ◽

Closed Form Solution ◽

Form Solution ◽

Flow Front ◽

Molding Process ◽

Transfer Molding ◽

Front Region ◽

Insight Into

A closed form solution to the flow of resin in vacuum assisted resin transfer molding process (VARTM) has been derived. VARTM is used extensively for affordable manufacturing of large composite structures. During the VARTM process, a highly permeable distribution medium is incorporated into the preform as a surface layer. During infusion, the resin flows preferentially across the surface and simultaneously through the preform giving rise to a complex flow front. The analytical solution presented here provides insight into the scaling laws governing fill times and resin inlet placement as a function of the properties of the preform, distribution media and resin. The formulation assumes that the flow is fully developed and is divided into two regimes: a saturated region with no crossflow and a flow front region where the resin is infiltrating into the preform from the distribution medium. The flow front region moves with a uniform velocity. The law of conservation of mass and Darcy’s Law for flow through porous media are applied in each region. The resulting equations are nondimensionalized and are solved to yield the flow front shape and the development of the saturated region. It is found that the flow front is parabolic in shape and the length of the saturated region is proportional to the square root of the time elapsed. The results thus obtained are compared to data from full scale simulations and an error analysis of the solution was carried out. It was found that the time to fill is determined with a high degree of accuracy while the error in estimating the flow front length, d, increases with a dimensionless parameter ε=K2xxh22/K2yyd2. The solution allows greater insight into the process physics, enables parametric and optimization studies and can reduce the computational cost of full-scale 3-dimensional simulations. A parametric study is conducted to establish the sensitivity of flow front velocity to the distribution media/preform thickness ratio and permeabilities and preform porosity. The results provide insight into the scaling laws for manufacturing of large scale structures by VARTM. [S1087-1357(00)02002-5]

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