Determination of the Thermal Dispersion Coefficient During Radial Filling of a Porous Medium

2003 ◽  
Vol 125 (5) ◽  
pp. 875-880 ◽  
Author(s):  
Mylene Deleglise ◽  
Pavel Simacek ◽  
Christophe Binetruy ◽  
Suresh Advani
Keyword(s):  
Porous Media ◽  
Dispersion Coefficient ◽  
Resin Transfer Molding ◽  
Liquid Composite Molding ◽  
Thermal Dispersion ◽  
Transfer Molding ◽  
Thermoset Resin ◽  
Composite Molding ◽  
Fibrous Porous Media

Resin Transfer Molding is one of the Liquid Composite Molding processes in which a thermoset resin is infiltrated into a fibrous porous media in a closed mold. To reduce the curing time of the resin, the mold may be heated, influencing other filling parameters such as the resin viscosity. Analysis of the non-isothermal effects during filling will help to understand the manufacturing process. One of the issues of non-isothermal filling in porous media is the variation of the velocity profile at the micro scale level, which as it is averaged, cannot be included in the convective term. To account for it, the thermal conductivity tensor is modified and a thermal dispersion coefficient Kd is introduced to model the micro convection effects. In this paper, we explore the temperature profile under non-isothermal conditions for radial injection during Resin Transfer Molding in order to determine the thermal dispersion coefficient. An approximate solution is derived from the series solution and validated with a numerical method. Experiments using carbon fibers and polyester resin were conducted. The thermal dispersion coefficient is determined by comparing experimental results with the steady state analytical solution. The comparison between radial and linear injection results shows that the same degree of dispersion is present in isotropic fibrous porous media.

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.

scholarly journals A Semi-Analytical Model to Predict Infusion Time and Reinforcement Thickness in VARTM and SCRIMP Processes

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 20 ◽  
Author(s):  
Felice Rubino ◽  
Pierpaolo Carlone
Keyword(s):  
Resin Transfer Molding ◽  
Resin Flow ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Transfer Molding ◽  
Deformable Porous Media ◽  
Filling Time ◽  
Composite Molding ◽  
Fabric Deformation ◽  
Porosity And Permeability

In liquid composite molding processes, such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM), the resin is drawn through fiber preforms in a closed mold by an induced pressure gradient. Unlike the RTM, where a rigid mold is employed, in VARTM, a flexible bag is commonly used as the upper-half mold. In this case, fabric deformation can take place during the impregnation process as the resin pressure inside the preform changes, resulting in continuous variations of reinforcement thickness, porosity, and permeability. The proper approach to simulate the resin flow, therefore, requires coupling deformation and pressure field making the process modeling more complex and computationally demanding. The present work proposes an efficient methodology to add the effects of the preform compaction on the resin flow when a deformable porous media is considered. The developed methodology was also applied in the case of Seeman’s Composite Resin Infusion Molding Process (SCRIMP). Numerical outcomes highlighted that preform compaction significantly affects the resin flow and the filling time. In particular, the more compliant the preform, the more time is required to complete the impregnation. On the other hand, in the case of SCRIMP, the results pointed out that the resin flow is mainly ruled by the high permeability network.

scholarly journals Mold Filling Simulation of Resin Transfer Molding Combining BEM and Level Set Method

2011 ◽  
Vol 62 ◽  
pp. 57-65 ◽  
Author(s):  
Renaud Gantois ◽  
Arthur Cantarel ◽  
Gilles Dusserre ◽  
Jean Noel Félices ◽  
Fabrice Schmidt
Keyword(s):  
Level Set ◽  
Resin Transfer Molding ◽  
Mold Design ◽  
Liquid Composite Molding ◽  
Two Dimensional ◽  
Dimensional Approach ◽  
Present Contribution ◽  
Transfer Molding ◽  
Composite Molding ◽  
Filling Simulation

Liquid Composite Molding (LCM) is a popular manufacturing process used in many industries. In Resin Transfer Molding (RTM), the liquid resin flows through the fibrous preform placed in a mold. Numerical simulation of the filling stage is a useful tool in mold design. In this paper the implemented method is based on coupling a Boundary Element Method (BEM) with a Level Set tracking. The present contribution is a two-dimensional approach, decoupled from kinetics, thermal analysis and reinforcement deformation occurring during the flow. Applications are presented and tested, including a flow close to industrial conditions.

Compression Resin Transfer Molding Using Inflatable Seals

2021 ◽  
Vol 900 ◽  
pp. 3-8
Author(s):  
Ahmed Ouezgan ◽  
Said Adima ◽  
Aziz Maziri ◽  
El Hassan Mallil ◽  
Jamal Echaabi
Keyword(s):  
Resin Transfer Molding ◽  
Mold Cavity ◽  
Liquid Composite Molding ◽  
Transfer Molding ◽  
Resin Injection ◽  
New Variant ◽  
Filling Time ◽  
Composite Molding ◽  
Fiber Reinforcements ◽  
Compression Resin Transfer Molding

Compression resin transfer molding using inflatable seals is a new variant of LCM (“Liquid composite molding”) processes, which uses the inflatable seals to compress the fiber reinforcements and drive the resin to impregnate the fabric preform, resulting to fill the entire mold cavity. During resin injection, the preform is relaxed. Consequently, the resin enters easily and quickly into the mold cavity. After, the necessary resin is injected into the mold cavity, the compression stage takes place, in a stepwise manner, by swelling the inflatable seals. The objective of this paper is to present this new process and study the effect of the number of inflatable seals on the filling time.

Textile-Integrated Elastomer Surface for Fiber Reinforced Composites

2019 ◽  
Vol 809 ◽  
pp. 53-58
Author(s):  
Jan Eric Semar ◽  
David May
Keyword(s):  
Impact Resistance ◽  
Liquid Composite Molding ◽  
Fiber Reinforced ◽  
Partial Immersion ◽  
Thermoset Resin ◽  
Fiber Reinforced Polymer Composites ◽  
Process Pressure ◽  
Wide Range ◽  
Composite Molding ◽  
Vulcanization Process

Elastomer layers offer a wide range of surface functionalization options for fiber-reinforced polymer composites (FRPC), e.g. erosion protection or increased impact resistance. Goal of this study was to investigate if it is possible to prepare a textile-based semi-finished product with elastomeric surface, which can easily be used as outermost layer in different liquid composite molding (LCM) processes. For this purpose, different types of elastomer were pressed and vulcanized onto a biaxial glass fiber fabric. Target of this procedure was to reach partial immersion of the elastomer into the textile with remaining dry textile areas. The dry areas of the textile can later be impregnated with a thermoset resin system. The strategy is to have the transition region between elastomer and thermoset within one textile layer and to give a robust and easy to handle semi-finished-product in order to achieve a maximum bonding strength of the elastomer surface to the final composite part. It could be shown by micrographs and computer tomography that the elastomer only penetrates the textile at its boundary. A remarkable microimpregnation of individual filaments within the rovings does not take place. Concerning the manufacturing, since water evaporates during vulcanization, a sufficient process pressure must be maintained throughout the entire vulcanization process to ensure a pore-free elastomer. Peel-off tests similar to DIN EN 28510-1 on the finished composite showed a failure in the laminate and not in the boundary layer between laminate and elastomer, so that the desired high joint strength could be demonstrated.

scholarly journals New Approach for Determining Tortuosity in Fibrous Porous Media

2010 ◽  
Vol 5 (3) ◽  
pp. 155892501000500 ◽  
Author(s):  
Rahul Vallabh ◽  
Pamela Banks-Lee ◽  
Abdel-Fattah Seyam
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Fiber Diameter ◽  
Empirical Relationship ◽  
Air Permeability ◽  
New Approach ◽  
Upper Limits ◽  
Fibrous Porous Media ◽  
Flow Through

A method to determine tortuosity in a fibrous porous medium is proposed. A new approach for sample preparation and testing has been followed to establish a relationship between air permeability and fiberweb thickness which formed the basis for the determination of tortuosity in fibrous porous media. An empirical relationship between tortuosity and fiberweb structural properties including porosity, fiber diameter and fiberweb thickness has been proposed unlike the models in the literature which have expressed tortuosity as a function of porosity only. Transverse air flow through a fibrous porous media increasingly becomes less tortuous with increasing porosity, with the value of tortuosity approaching 1 at upper limits of porosity. Tortuosity also decreased with increase in fiber diameter whereas increase in fiberweb thickness resulted in the increase in tortuosity within the range of fiberweb thickness tested.

Process-Oriented Determination of Preform Permeability and Matrix Viscosity during Mold Filling in Resin Transfer Molding

2015 ◽  
Vol 825-826 ◽  
pp. 822-829 ◽  
Author(s):  
Dino Magagnato ◽  
Frank Henning
Keyword(s):  
Flow Behavior ◽  
Resin Transfer Molding ◽  
Matrix Material ◽  
Low Flow ◽  
Test Fluid ◽  
Transfer Molding ◽  
Reinforced Plastics ◽  
The Matrix ◽  
Reactive Matrix

The resin transfer molding (RTM) offers great conditions for mass production of fiber reinforced plastics. In this process, preformed fiber textiles are infiltrated with matrix material (for example: epoxy resin). During the infiltration, the matrix material starts a curing process until the complete consolidation. After the de-molding and a short post-processing step, the final part is ready to use. To reduce the cycle time for the RTM manufacturing, it is necessary to model and predict the flow behavior of the matrix material in a realistic way. An important parameter is the preform permeability, which characterizes the flow resistance of fibers against the flowing matrix material.In this study a new measurement setup is presented, which is able to determine the permeability directly during the manufacturing process, with integrated pressure and temperature sensors. This approach has many advantages against conventional measurement setups, that try to recreate the RTM process with a simple replication. With these replicas, it is only possible to simulate low flow velocities and pressures. Dynamic effects that occur at higher velocities cannot be regarded. Furthermore, the new setup has the advantage that measurement artifacts, like capillarity, have a lower impact. In addition to that, the infiltration can be done with a constant viscosity test fluid as well as with reactive matrix material. Thus, it allows further determination of the time depending viscosity.

Investigations on Impregnation Effects on a Non-Crimp Fiber Bed

Materials ◽  
2005 ◽  
Author(s):  
M. Repsch ◽  
U. Huber ◽  
S. Rief ◽  
D. Kehrwald ◽  
K. Steiner
Keyword(s):  
Flow Behavior ◽  
Liquid Composite Molding ◽  
Fiber Structure ◽  
Viscosity Characteristic ◽  
Composite Molding ◽  
Mesoscopic Level ◽  
Evaluation Techniques ◽  
Flow Experiments ◽  
Very High

Permeability and viscosity are the key input parameters for performing LCM (Liquid Composite Molding). Currently the measurement expenses for the determination of permeability are very high. In order to reduce these expenses and to predict the permeability value in a more theoretical manner the interaction between fiber bed and impregnating fluid has to be clarified. This paper presents an overview about experimental and evaluation techniques in order to identify interaction of fluid and dry fiber structure driven impregnation. Flow experiments are executed using an epoxy resin and a non-crimp fiber bed. Attention is paid to the global flow behavior as well as to the impregnation effects on a mesoscopic level. Additionally the viscosity characteristic of the resin used is investigated. Finally basic micro structural simulations are performed and verified by the evaluation of the flow experiments.

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