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.

Study of the Proper Sintering Conditions of Anionically-Polymerized Polyamide 6 Matrices for the Fabrication of Greencomposites

2012 ◽  
Vol 713 ◽  
pp. 121-126
Author(s):  
A. Alfonso ◽  
J. Andrés ◽  
J.A. García
Keyword(s):  
Material Characterization ◽  
Mechanical Performance ◽  
In Situ Polymerization ◽  
Research Work ◽  
Polyamide 6 ◽  
Liquid Composite Molding ◽  
Thermoplastic Matrix ◽  
Composite Molding ◽  
Long Fiber Thermoplastic

The present research work assesses the manufacture of long fiber thermoplastic matrix composite materials (GreenComposites). Thermoplastic matrices are too viscous to be injected into the conventional LCM (Liquid Composite Molding) molds, and then epoxy, polyester or vinylester resins are used. Nevertheless, the groundbreaking anionic polymerization of caprolactam allows such a synthesis of a thermoplastic APA6 matrix inside the mold. This matrix is sintered from the starting monomers, and presents high mechanical performance and recyclability. In order to do the reactive injection in a LCM mold, it is necessary to control the polymerization mechanism of such a thermoplastic matrix. This paper puts special emphasis on detecting and solving all problems which arose during synthesis. For instance, moisture values were assessed for all starting reactants, since humidity keeps polymerization from occurring. It is thought that once the synthesis and the resulting material characterization are well controlled, the manufacture of GreenComposites through in situ polymerization, as well as addition of state-of-the-art fabrics such as basalt, can proceed successfully.

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.

Modeling void formation and unsaturated flow in liquid composite molding processes: a survey and review

2011 ◽  
Vol 30 (11) ◽  
pp. 957-977 ◽  
Author(s):  
Chung Hae Park ◽  
Lee Woo
Keyword(s):  
Unsaturated Flow ◽  
State Of The Art ◽  
Void Formation ◽  
Pressure Profile ◽  
Liquid Composite Molding ◽  
Simulation Studies ◽  
Apparent Permeability ◽  
Composite Molding ◽  
Unsaturated Flows ◽  
Key Parameter

In this study, we present a review of the modeling of void formation and unsaturated flow in liquid composite molding processes. We examine modeling efforts considering all the mechanisms involved such as void formation and transport, bubble compression, and gas dissolution. In particular, the capillary number is identified as a key parameter for void formation and transport. Numerical simulation studies are reviewed, and a state-of-the-art is presented. The influence of microvoids on the global resin flow is also investigated. To model the unsaturated flow more accurately, we suggest considering the surface tension or capillary pressure, variation in permeability in terms of saturation and fiber displacement, as well as tow saturation. From this investigation, the apparent permeability and pressure profile in saturated and unsaturated flows are compared.

In Situ Visualization Measurement of Flat Plate Ablation in High-Temperature Gas Flow

2018 ◽  
Vol 85 (6) ◽  
Author(s):  
Zhe Qu ◽  
Xian Wang ◽  
Yunlong Tang ◽  
Honghong Su ◽  
Lianzhong Chen ◽  
...  
Keyword(s):  
Flat Plate ◽  
Thermal Ablation ◽  
Gas Flow ◽  
Feature Detection ◽  
Thermal Protection ◽  
Experimental Results ◽  
Image Feature ◽  
In Situ Observation ◽  
Optoelectronic System

In this work, we develop an optoelectronic system for in situ observation and measurement in hypervelocity flows. The system has the advantages of strong radiation resistance and self-adaptive exposure time of the cameras. Thermal ablation test using flat plate thermal protection system material was carried out in an arc jet. Real-time ablation images were captured and analyzed to understand the thermal ablation mechanism. Through the modified algorithms of particle image velocity (PIV) and image feature detection, the surface recession rate and the velocity distribution of the melted droplets flowing on the sample surface were obtained. The experimental results demonstrate vast potential for using this in situ measuring technique in various engineering applications. Finally, the formation and merging of the melted droplets was analyzed based on energy theory, and the numerical simulation results showed good agreement with the actual experimental results.

In-situ monitoring of liquid composite molding process using piezoelectric sensor network

2020 ◽  
pp. 147592172095808
Author(s):  
Xinlin Qing ◽  
Xiao Liu ◽  
Jianjian Zhu ◽  
Yishou Wang
Keyword(s):  
Sensor Network ◽  
Lead Zirconate Titanate ◽  
Large Scale ◽  
Lead Zirconate ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Zirconate Titanate ◽  
Composite Molding ◽  
Piezoelectric Lead Zirconate Titanate

The excellent properties of advanced composite materials provide great opportunities for making industrial structures large-scale and intelligent. Liquid composite molding process is suitable for manufacturing complex large-scale composite structures and has the potential for low cost and mass production. In present work, the concept of Networked Elements for Resin Visualization and Evaluation network was developed to measure and monitor the manufacturing process in-situ. This paper investigates the capability of piezoelectric lead-zirconate-titanate sensors in the Networked Elements for Resin Visualization and Evaluation network to monitor two important parameters in liquid composite molding process, including the resin flow front and the progress of the reaction. The piezoelectric lead-zirconate-titanate sensor network can be integrated with a composite structure either installed on the interface between the mold and laminates or embedded inside the laminates during the liquid composite molding process. Experimental results demonstrated that the liquid composite molding process can be effectively monitored by the embedded Networked Elements for Resin Visualization and Evaluation network with a piezoelectric lead-zirconate-titanate sensor network.

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.

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