Gate Effectiveness in Controlling Resin Advance in Liquid Composite Molding Processes

2003 ◽  
Vol 125 (3) ◽  
pp. 548-555 ◽  
Author(s):  
Ali Gokce ◽  
Suresh G. Advani
Keyword(s):  
Flow Dynamics ◽  
Liquid Composite Molding ◽  
Simulation Environment ◽  
Flow Front ◽  
Fiber Preform ◽  
Composite Part ◽  
Resin Impregnation ◽  
Composite Molding ◽  
Front Shape

In Liquid Composite Molding (LCM) processes, the flow pattern of the resin in the mold cavity during mold filling dictates the quality of the composite part. Disturbances such as uncertainty in the fiber preform permeability, variations in the resin viscosity, and racing of the resin along the mold walls may create unexpected and unanticipated flow patterns that could result in dry spots in the preform. Process control with sensor feedback can potentially provide the ability to make fully impregnated parts despite various disturbances by manipulating the flow front movement during resin impregnation through modification of the injection conditions at the gates. Studies have shown that under certain conditions, the flow front shape is not influenced by even large changes in the flow rate or the pressure at the injection gates. This study investigates gate effectiveness in modifying the flow front shape by analyzing the flow dynamics and conducting a parametric study in a simulation environment.

Role of vacuum pressure and port locations on flow front control for liquid composite molding process

2001 ◽  
Vol 22 (5) ◽  
pp. 660-667 ◽  
Author(s):  
Kuang-Ting Hsiao ◽  
John W. Gillespie ◽  
Suresh G. Advani ◽  
Bruce K. Fink
Keyword(s):  
Vacuum Pressure ◽  
Liquid Composite Molding ◽  
Flow Front ◽  
Molding Process ◽  
Composite Molding

Flow-induced deformation of unidirectional carbon fiber preform during the mold filling stage in liquid composite molding process

2017 ◽  
Vol 52 (9) ◽  
pp. 1265-1277 ◽  
Author(s):  
Dong Gi Seong ◽  
Shino Kim ◽  
Moon Kwang Um ◽  
Young Seok Song
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Orientation Angle ◽  
Mold Filling ◽  
Liquid Composite Molding ◽  
Fiber Preform ◽  
Molding Process ◽  
Controllable Factors ◽  
Composite Molding ◽  
Fiber Deformation

Liquid composite molding has been developed as a high-speed process for manufacturing automotive lightweight parts using new equipment that applies a high pressure for mixing and injection. One of the technical issues is the deformation of fiber preform during the process, which causes defects in the size, mechanical properties and appearance of the final products. In this study, two types of deformation in unidirectional fiber preform during the mold filling process are investigated, which are rigid body deformation and local deformation. Three important forces, namely friction, in-mold stiffness of fiber preform and resin flow, are measured to investigate the mechanism of the fiber deformation. The magnitude of the forces was compared at an instant, which influenced the types of fiber deformation. The effects of the orientation angle and the volume fraction of fiber preform and flow rate were investigated to identify controllable factors to prevent undesired deformation during the process.

In-Situ Measurement and Monitoring of Fiber Preform Permeability for Liquid Composite Molding

2000 ◽  
Author(s):  
Zhiyong Liang ◽  
Chuck Zhang ◽  
Ben Wang ◽  
Chiang Shih
Keyword(s):  
Gas Flow ◽  
Gas Permeability ◽  
Pressure Profile ◽  
Air Permeability ◽  
Experimental Results ◽  
Liquid Composite Molding ◽  
Permeability Measurement ◽  
Fiber Preform ◽  
Composite Molding

Abstract In a liquid composite molding (LCM) process such as resin transfer molding (RTM), quality control depends on an in-situ permeability profile of the fibrous preform taken just before resin injection. However, the conventional permeability measurement method, which uses liquid (oil or resin) as its working fluid, only measures the average preform permeability in an off-line mode. It cannot be used to create an in-situ permeability profile because of fiber pollution, and cannot be used to reveal local permeability variations of preform. This study develops a new permeability characterization method that uses gas flow and pressure profiles to measure preform permeability variation in a closed mold assembly. This method is based upon two research findings: (1) that the air permeability of a preform can be obtained through measuring the pressure profile of gas flow, and (2) that resin permeability is highly correlated with air permeability for the same fiber preform. In this paper, the validity of this method is discussed. Experimental results of gas permeability measurement with defective and defect-free preforms are presented, and quantitative models for correlation of gas permeability versus pressure profile and of gas permeability versus resin permeability are also provided. Finally, the efficacy of the proposed method is illustrated through experimental results.

scholarly journals Influence of Non-Reactive Epoxy Binder on the Permeability and Friction Coefficient of Twill-Woven Carbon Fabric in the Liquid Composite Molding Process

2020 ◽  
Vol 10 (20) ◽  
pp. 7039
Author(s):  
Hyeong Min Yoo ◽  
Jung Wan Lee ◽  
Jung Soo Kim ◽  
Moon Kwang Um
Keyword(s):  
Heat Treatment ◽  
Friction Coefficient ◽  
Flow Velocity ◽  
Maximum Flow ◽  
Epoxy Binder ◽  
Liquid Composite Molding ◽  
Carbon Fabric ◽  
Molding Process ◽  
Resin Impregnation ◽  
Composite Molding

In the liquid composite molding process, a binder is used to fix the preform. In this study, the influence of a non-reactive epoxy binder was investigated. To allow the measurement of permeability, the preform specimen was produced under three preforming conditions: neat fabric preform, binder-treated fabric preform without heat treatment, and binder-treated fabric preform with heat treatment. The in-plane directional permeability, K1 (having maximum flow velocity), and K2 (having minimum flow velocity) of the binder-treated fabric preform decreased approximately 80% compared to the neat fabric preform. The permeability in the out-of-plane direction decreased approximately 80% in the binder-treated fabric preform without heat treatment and about 98% in the binder-treated fabric preform with heat treatment. This decrease occurred because the treated binder on the fiber hindered resin impregnation. The effect of the binder on the friction coefficient of carbon fabric was also investigated. The friction coefficient was high when the binder was on the friction surface and increased 40–200% at 110 °C, compared to 25 °C.

Modeling of Transient Flow inside a Fiber Tow During Liquid Composite Molding

Materials ◽  
2005 ◽  
Author(s):  
N. K. Yamaleev ◽  
R. V. Mohan
Keyword(s):  
Transient Flow ◽  
Flow Behavior ◽  
Model Development ◽  
Void Formation ◽  
Resin Flow ◽  
Liquid Composite Molding ◽  
New Model ◽  
Resin Impregnation ◽  
Sink Term ◽  
Composite Molding

In liquid composite molding processes, the macroscopic flow in fiber preforms is simultaneously accompanied by the micro-scale impregnation of fiber tows. Because the interstitial space within an individual fiber tow is much smaller than the space between tows themselves, the macroscopic flow front is able to reach the downstream side of the tow before gas entrapped inside the tow can be forced out by the resin impregnation process. In this work, a quasi-2-D model for the dynamic flow behavior inside a fiber tow completely surrounded by a macroscopic resin flow is developed. In contrast to the existing models, the new model accounts for not only the surface tension effects that could influence the flow behavior at this length scale, but also the multidimensional effects and the vapor-liquid phase transition of the entrapped gas, which occurs in resin systems used in liquid composite molding. This model simulates the transient dynamics of the multi-component gas mixture entrapped inside the tow on the time scale associated with infiltrating the intra-tow region. One of the advantages of the new model is its ability to account for the delayed impregnation inside fiber tows, which eliminates the ambiguity in determining the intra-tow infiltration time of the “sink” volume, which is a required parameter for some previously developed models. The model also quantitatively predicts the time-dependent behavior of the sink term, which is needed to accurately simulate the macroscopic resin flow in the preform. The model development and analysis of the transient intra-tow flow behavior under various thermodynamic conditions are presented, and the relevance of the numerical results to the micro-void formation in liquid composite molding processes is discussed.

Simulation of Reactive Liquid Composite Molding

1998 ◽  
Vol 13 (4) ◽  
pp. 389-397 ◽  
Author(s):  
C.-H. Wu ◽  
H.-T. Chiu ◽  
L. J. Lee ◽  
S. Nakamura
Keyword(s):  
Liquid Composite Molding ◽  
Composite Molding ◽  
Reactive Liquid
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