Experimental Investigation of the Effect of Fiber-mat Architecture on the Unsaturated Flow in Liquid Composite Molding

2004 ◽  
Vol 38 (1) ◽  
pp. 57-79 ◽  
Author(s):  
Baiju Z. Babu ◽  
Krishna M. Pillai
Keyword(s):  
Experimental Investigation ◽  
Unsaturated Flow ◽  
Liquid Composite Molding ◽  
Composite Molding

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.

First Steps Towards Quantitative Validation of the Unsaturated-Flow Theories in Liquid Composite Molding

2003 ◽  
Author(s):  
Tonmoy Roy ◽  
Baiju Z. Babu ◽  
Krishna M. Pillai
Keyword(s):  
Pore Volume ◽  
Unsaturated Flow ◽  
Volume Ratio ◽  
Mold Filling ◽  
Inlet Pressure ◽  
Liquid Composite Molding ◽  
Fiber Mats ◽  
Pressure History ◽  
Composite Molding ◽  
Dual Scale

In liquid composite molding technologies such as Resin Transfer Molding (RTM), a thermoset resin is injected into a mold cavity with a pre-placed preform made of fiber mats to create a cured part. In order to improve the physics of resin flow in dual-scale (woven, stitched or braided) fiber mats, the authors carried out many transient 1-D mold-filling experiments to investigate the onset of unsaturated flow through the inlet-pressure history. Their study revealed that the measured pressure history, which droops downwards for dual-scale fiber mats, is at a variance with the linear pressure profile predicted by state-of-the-art Liquid Composite Molding (LCM) mold-filling simulation physics. It was also observed that the drooping of the inlet pressure increases with an increase in the compression of fiber mats. In this paper, the correlation between a previously proposed dimensionless number pore volume ratio and the droop in the inlet pressure history has been sought. Studying the micrographs of composite samples, pore volume ratio is measured for various fiber mat compression. It is observed that the droop in the inlet pressure profiles increase with an increase in the pore volume ratio. This is the first attempt to quantitatively validate the previous theories on the unsaturated flow.

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