scholarly journals NUMERICAL ANALYSIS OF INFUSION STRATEGIES IN VACUUM ASSISTED RESIN TRANSFER MOLDING (VARTM) PROCESS

2021 ◽  
Vol 13 (3) ◽  
pp. 117-124
Author(s):  
Himanshu V. Patel ◽  
◽  
Harshit K. Dave ◽  
Keyword(s):  
Resin Transfer Molding ◽  
Mold Filling ◽  
Vital Role ◽  
Simulation Approach ◽  
Gating System ◽  
Composite Manufacturing ◽  
Transfer Molding ◽  
Filling Stage ◽  
Filling Time ◽  
Vartm Process

The Liquid composite Molding (LCM) process, such as Vacuum Assisted Resin Transfer Molding (VARTM), offers a fast and high-quality production of composites laminates. In the VARTM process, the simulation tool is found beneficial to predict and solve composite manufacturing issues. The part quality is dependent on the resin mold filling stage in the VARTM process. The infiltration of resin into a porous fibrous medium is taken place during the resin mold filling stage. The permeability has a crucial role during the resin mold filling stage. In this study, simulation of resin infusion through multiple injection gates is discussed. The various infusion schemes are simulated to identify defect-free composite manufacturing. The simulation approach is applied to five different stacking sequences of reinforcements. In this transient simulation study, permeability and resin viscosity is essential inputs for the resin flow. The simulation approach found that a gating scheme plays a vital role in mold filling time and defect-free composite fabrication. It is found that the line gating system can be useful for fast mold filling over the point gating system.

Modeling of Distribution Media and Vacuum Bag Properties on Permeability Variations During Vacuum Assisted Resin Transfer Molding (VARTM)

2005 ◽  
Author(s):  
Yuhong Zhang ◽  
Sergey Lopatnikov ◽  
Dirk Heider
Keyword(s):  
Analytical Model ◽  
Resin Transfer Molding ◽  
Flow Simulations ◽  
Transfer Molding ◽  
Media Design ◽  
Filling Time ◽  
Parametric Studies ◽  
Systems Simulation ◽  
First Time ◽  
Vartm Process

This paper investigates the deformation of the vacuum film into the distribution media, its effect on the change of the unit cell porosity and ultimately the reduction of permeability of the overall system in a Vacuum Assisted Resin Transfer Molding (VARTM) process. Experimental results have shown the obvious effects of the vacuum bagging penetration into the distribution media on permeability; however, there is no analytical model to explicitly characterize this phenomenon. In this paper, we proposed an analytical model to capture the vacuum film penetration into the distribution media based on an energy approach for the first time, and then we connect this analytical model with Carman-Kozeny equation to predict the permeability variations in terms of the parameters of plastic vacuum bag and distribution media. Design curves are obtained in parametric studies to predict the permeability reduction as a function of bag modulus and thickness, and distribution media geometry. These reduction factors can be used in flow simulations to accurately predict the resin filling time for a wide variety of distribution media/flexible bag systems. Simulation results are compatible with observations from the preliminary experiment results.

Effects of Weirs on the Resin Transfer Molding Process

2001 ◽  
Author(s):  
Kiran M. D’Silva ◽  
Su-Seng Pang ◽  
Kurt C. Schulz
Keyword(s):  
Glass Fibers ◽  
Resin Transfer Molding ◽  
Mold Filling ◽  
Laminated Plates ◽  
Molding Process ◽  
Outlet Port ◽  
Transfer Molding ◽  
Inlet Port ◽  
Rtm Process ◽  
Filling Time

Abstract Low mold filling time and improper fiber wetting are the main problems faced by the manufacturers applying the Resin Transfer Molding (RTM) process. The objective of this work was to minimize these problems and to study the effect of weirs on the RTM process. A mold was designed such that the lower mold plate contains two weirs, one at the resin inlet port and the other at the outlet port. The purpose of adding the weirs is to provide a continuous inlet stream near the resin inlet port and to cause backpressure near the outlet port to induce complete mold filling. Laminated plates were prepared using glass fibers and epoxy resin (combination of EPON resin-862 and curing agent W). The test parameters investigated, such as void contents, dry spots and mold filling time, were compared with those of samples that were prepared without the use of weirs. It was found that the presence of weirs resulted in significant elimination of dry spots, minimization of void contents and a reduction in mold filling time. As a result, the cost required to manufacture composite parts can be reduced by the use of weirs. In addition to the experimental investigation, a computer simulation (using LCMFLOT software) of resin flow inside the mold cavity was conducted. Many simulations were run in order to optimize the height and shape of the weir. Rectangular weirs of height 2.54 mm showed minimum mold fill time. It was found that the results obtained from the experimental work and flow simulations are in good agreement. Based on this work, it is evident that complex parts can be produced in less cycle time if weirs are positioned at appropriate locations.

Flow and Mold Filling Modeling and Simulation to Enhance Resin Transfer Molding Processes

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
C. J. Mosella ◽  
J. P. Montecinos ◽  
J. A. Ramos-Grez
Keyword(s):  
Resin Transfer Molding ◽  
Mass Conservation ◽  
Mold Filling ◽  
Complete Wetting ◽  
Air Bubble ◽  
Transfer Molding ◽  
Numerical Resolution ◽  
Filling Time ◽  
Manufacturing Time

Among the multiple stages of the resin transfer molding (RTM) processes, flow and mold filling of injected resin correspond to the most complex and crucial stage. During the latter, air bubble agglomeration must be avoided and complete wetting of fibers must be achieved in order to ensure the maximum quality of the parts at the lowest possible manufacturing time. Focusing on these manufacturing issues, a mathematical model and a numerical resolution are presented to predict the resin flow throughout the fiber reinforcement inside the mold cavity. The methodology employs conventional finite element techniques for solving the flow problem through a porous medium governed by Darcy’s law and mass conservation. Simultaneously, a state of the art numerical scheme known as the discontinuous Galerkin method is implemented to determine the location and shape of the advancing flow fronts ruled by a hyperbolic transport equation. These two schemes are implemented to work with a two-dimensional domain, handling diverse geometries with multiple injection and ventilation ports. The results for key process parameters, such as filling time and position of the advancing flow fronts, show a good agreement with results from analytical solutions for particular cases and from empirical data. When several simulated results are taken into account in the design process of RTM cavities, the overall process could be enhanced.

A Study on Resin Flow through a Multi-layered Preform in Resin Transfer Molding

2002 ◽  
Vol 10 (7) ◽  
pp. 493-510 ◽  
Author(s):  
D. G. Seong ◽  
K Chung ◽  
T. J. Kang ◽  
J. R. Youn
Keyword(s):  
Resin Transfer Molding ◽  
Mold Filling ◽  
Transverse Flow ◽  
Woven Fabrics ◽  
Weighted Averaging ◽  
Resin Flow ◽  
Flow Front ◽  
Transfer Molding ◽  
Filling Time ◽  
Flow Through

In resin transfer molding, mold filling is governed by the flow of resin through a preform which is considered as an anisotropic porous media. The resin flow is usually described by Darcy's law and the permeability tensor must be obtained for filling analysis. When the preform is composed of more than two layers with different in-plane permeability, effective average permeability should be determined for the flow analysis in the mold. The most frequently used averaging scheme is the weighted averaging scheme, but it does not account for the transverse flow between adjacent layers. A new averaging scheme is suggested to predict the effective average permeability of the multi-layered preform, which accounts for the transverse flow effect. When the flow in the mold is unsaturated, the effective average permeability is predicted by using the predicted mold filling time and transverse permeability. The new scheme is verified by measuring the effective permeability of the multi-layered preforms which consist of glass fiber random mats, carbon fiber woven fabrics, aramid fiber woven fabrics. Fluid flow through the preform composed of more than two layers with different in-plane permeability shows different flow fronts between layers. The difference in the flow front advancement is observed with a digital camcorder. The predicted flow front is compared with the experimental results and shows a good agreement. It is expected that the effective average permeability can be used for modeling the resin flow through the multi-layered preform.

Analysis of Resin Transfer Molding With High Permeability Layers

1998 ◽  
Vol 120 (3) ◽  
pp. 609-616 ◽  
Author(s):  
M. J. Tari ◽  
J. P. Imbert ◽  
M. Y. Lin ◽  
A. S. Lavine ◽  
H. T. Hahn
Keyword(s):  
Complex Geometry ◽  
Resin Transfer Molding ◽  
Mold Filling ◽  
Process Efficiency ◽  
High Permeability ◽  
Capital Costs ◽  
Transfer Molding ◽  
Analysis Experiment ◽  
Filling Time ◽  
Two Dimensional Flow

In resin transfer molding (RTM) a high permeability layer (HPL) is placed on top of the fiber mat lay-up to reduce mold filling time and increase the ultimate distance resin can be drawn into the mold. HPL’s are particularly useful in vacuum bag resin transfer molding (VBRTM), where driving pressures are relatively low. When compared to traditional closed mold RTM, VBRTM has the advantages of low capital costs and short start up time. The goal of the current research is to investigate how an HPL can be used to improve quality and process efficiency for parts of complex geometry made by both conventional and vacuum bag RTM. As a first step towards this goal, the effect of the HPL on the flow field has been studied through analysis, experiment and simulation. As expected, the use of the HPL creates a transverse (i.e., top-to-bottom) flow in the fiber mat, facilitating mold filling. The thickness of the HPL has been varied to determine the effects on the flow front. The experimental results validate the capability of the simulation to model two-dimensional flow in a porous medium with heterogeneous permeability.

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.

Sign in / Sign up

Export Citation Format

Share Document