Use of Resin Transfer Molding Simulation to Predict Flow, Saturation, and Compaction in the VARTM Process

2004 ◽  
Vol 126 (2) ◽  
pp. 210-215 ◽  
Author(s):  
N. C. Correia ◽  
F. Robitaille ◽  
A. C. Long ◽  
C. D. Rudd ◽  
P. Sˇima´cˇek ◽  
...  
Keyword(s):  
Resin Transfer Molding ◽  
Flow Simulation ◽  
Continuity Condition ◽  
Simulation Software ◽  
Molding Process ◽  
Numerical Work ◽  
Transfer Molding ◽  
Outlet Pressure ◽  
Analytical Work ◽  
Vartm Process

The present paper examines the analysis and simulation of the vacuum assisted resin transfer molding process (VARTM). VARTM differs from the conventional resin transfer molding (RTM) in that the thickness of the preform varies during injection affecting permeability and fill time. First, a governing equation for VARTM is analytically developed from the fundamental continuity condition, and used to show the relation between parameters in VARTM. This analytical work is followed by the development of a numerical 1-D/2-D solution, based on the flow simulation software LIMS, which can be used to predict flow and time dependent thickness of the preform by introducing models for compaction and permeability. Finally, the results of a VARTM experimental plan, focusing on the study of the influence of outlet pressure on compaction and fill time, are correlated with both the analytical and the numerical work. The present work also proposes an explanation for the similarities between VARTM and RTM and shows when modeling VARTM and RTM can result in an oversimplification.

Use of Resin Transfer Molding Simulation to Predict Flow, Saturation and Compaction in the VARTM Process

2002 ◽  
Author(s):  
N. C. Correia ◽  
F. Robitaille ◽  
A. C. Long ◽  
C. D. Rudd ◽  
P. Sˇima´cˇek ◽  
...  
Keyword(s):  
Resin Transfer Molding ◽  
Molding Process ◽  
Transfer Molding ◽  
Injection Process ◽  
Software Packages ◽  
Compaction Force ◽  
Thickness Variations ◽  
Filling Simulation ◽  
Complex Parts ◽  
Vartm Process

Vacuum Assisted Resin Transfer Molding (VARTM) and Resin Transfer Molding (RTM) are among the most significant and widely used Liquid Composite manufacturing processes. In RTM preformed-reinforcement materials are placed in a mold cavity, which is subsequently closed and infused with resin. RTM numerical simulations have been developed and used for a number of years for gate assessment and optimization purposes. Available simulation packages are capable of describing/predicting flow patterns and fill times in geometrically complex parts manufactured by the resin transfer molding process. Unlike RTM, the VARTM process uses only one sided molds (tool surfaces) where performs are placed and enclosed by a sealed vacuum bag. To improve the delivery of the resin, a distribution media is sometimes used to cover the preform during the injection process. Attempts to extend the usability of the existing RTM algorithms and software packages to the VARTM domain have been made but there are some fundamental differences between the two processes. Most significant of these are 1) the thickness variations in VARTM due to changes in compaction force during resin flow 2) fiber tow saturation, which may be significant in the VARTM process. This paper presents examples on how existing RTM filling simulation codes can be adapted and used to predict flow, thickness of the preform during the filling stage and permeability changes during the VARTM filling process. The results are compared with results obtained from an analytic model as well as with limited experimental results. The similarities and differences between the modeling of RTM and VARTM process are highlighted.

Numerical study of filling strategies in vacuum assisted resin transfer molding process

2015 ◽  
Vol 35 (5) ◽  
pp. 493-501 ◽  
Author(s):  
Chih-Yuan Chang
Keyword(s):  
Numerical Study ◽  
Resin Transfer Molding ◽  
Thickness Variation ◽  
Filling Process ◽  
Molding Process ◽  
Resin Infusion ◽  
Numerical Work ◽  
Transfer Molding ◽  
Practical Standpoint ◽  
Post Infusion

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.

The Thickness and the Inerior Quality of Composite Panel in the Vacuum Assisted Resin Transfer Molding Process

2011 ◽  
Vol 686 ◽  
pp. 468-473
Author(s):  
Yan Liang Li ◽  
Xiao Su Yi ◽  
Bang Ming Tang
Keyword(s):  
Fiber Composite ◽  
Low Cost ◽  
Resin Transfer Molding ◽  
Composite Panel ◽  
Flow Front ◽  
Carbon Fiber Composite ◽  
Molding Process ◽  
Transfer Molding ◽  
Vartm Process

The objective of this paper was focused on predicting the thickness and the interior quality of carbon fiber composite panel during the vacuum assisted resin transfer molding (VARTM) process. The character of the VARTM process determined that it was low cost. A panel made of Epoxy resin, and carbon fibers, was used as the simplest article to experiment and except routine items, the thickness and the interior quality was focused. In the process, the flow front of the resin was record using a digital camera. Darcy’s law was the model of resin flow. The results showed that the flow front history would reach unanimous, thickness near the edges was difficult to control, and most of the porosity came from the injection line where more resin cumulated.

Flow Characteristics of Vacuum Assisted Resin Transfer Molding Process Depending on the Capillary Phenomenon

2013 ◽  
Vol 762 ◽  
pp. 612-620 ◽  
Author(s):  
Yun Hae Kim ◽  
Jin Woo Lee ◽  
Jun Mu Park
Keyword(s):  
Low Cost ◽  
Resin Transfer Molding ◽  
Flow Characteristics ◽  
Molding Process ◽  
Transfer Molding ◽  
Filling Stage ◽  
Resin Impregnation ◽  
Movement Mechanism ◽  
Capillary Phenomenon ◽  
Vartm Process

Reducing the cost of composite material production is significant for expanding its usage and application in many ways, such as in the fields of aerospace, aviation, ocean industry and so on. To do this, It is important to minimize the production process of the material and to decrease the amount of scraps or any unnecessary particles. The Vacuum Assisted Resin Transfer Molding (VARTM) process, which is known for having many advantages, has become recognized as one of the most low-cost manufacturing model. VARTM process can be divided into three main steps: performing, resin filling and hardening steps. The most important step among all these three steps is the Resin Filling stage, a process when resin is impregnated into the mat. Mostly, Resin Filling stage is greatly affected by the level of permeability, a characteristic of stiffener due to pneumatic resistant nature in the process. Other factors such as viscosity, technological vacuuming, or even stiffening process itself could also influence the production as well. During Resin Filling stage, Resin tends to spread out in the center first because of capillary phenomenon. In this research, the researchers examined the mechanical property and the pneumatic nature of Resin by dividing the pneumatic movement of the Resin into sections. Based on this result, the researchers found the correlations between the capillary phenomenon and Resin impregnation, and analyzed the movement mechanism in Resin filling stage.

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.

Development of resin transfer molding process using scaling down strategy

2013 ◽  
Vol 35 (9) ◽  
pp. 1683-1689 ◽  
Author(s):  
Raghu Raja Pandiyan Kuppusamy ◽  
Swati Neogi
Keyword(s):  
Resin Transfer Molding ◽  
Molding Process ◽  
Transfer Molding ◽  
Scaling Down

scholarly journals Resin transfer molding process: a numerical and experimental investigation

2013 ◽  
Vol 7 (2) ◽  
pp. 125-136 ◽  
Author(s):  
Iran de Oliveira ◽  
Sandro Amico ◽  
Jeferson Souza ◽  
Antonio de Lima
Keyword(s):  
Experimental Investigation ◽  
Resin Transfer Molding ◽  
Molding Process ◽  
Transfer Molding

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

1999 ◽  
Vol 122 (3) ◽  
pp. 463-475 ◽  
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]

Analysis of the resin transfer molding process using in-mold dielectric sensors

1993 ◽  
Vol 217 ◽  
pp. 251-262 ◽  
Author(s):  
D.J. Melotik ◽  
M. Czaplicki ◽  
T.J. Whalen ◽  
D.R. Day
Keyword(s):  
Resin Transfer Molding ◽  
Molding Process ◽  
Transfer Molding ◽  
Dielectric Sensors
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