VARTM is a low-cost process capable of manufacturing large-scale complex geometry composite parts with good surface finish and excellent dimensional tolerances. Double bag vacuum infusion process is an improved version of conventional VARTM. This process adds a second vacuum bag separated by a layer of breather cloth to the conventional VARTM setup. The pressure in the inner bag drives the resin to infuse the laminate, while the pressure in the outer bag keeps the laminate compacted throughout the infusion. Double bagging process is of particular interest to the robust VARTM development, as it is claimed to result in better infusion, higher fiber volume fraction, reduced thickness gradient, reduced void content, and improved vacuum integrity. This paper is based on the results of series of 1-D permeability experiments that were carried out to study the changes to the preform permeability under single and double bagging conditions for thin laminates. Permeability of the preform is one of the major parameters needed to properly simulate and optimize the VARTM process. The permeability was experimentally determined using custom image acquisition and analysis software developed in Matlab. As a part of the experiment, the thickness gradient and the fiber volume fractions of the cured laminate were also measured. The experimental results were used to quantify the relative benefits of double bagging for thin carbon-epoxy laminates.

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Conference SAMPE 2010 Conference and Exhibition "New Materials and Processes for a New Economy"
Pant, S. (Shashank), Mahendran, M. (Mario), Straznicky, P.V. (Paul V.), & Laliberte, J. (2010). Characterization of double-bagging effects on 1-D permeability for vacuum assisted resin transfer moulding (VARTM) process. Presented at the SAMPE 2010 Conference and Exhibition "New Materials and Processes for a New Economy".