Abstract

Vacuum Assisted Resin Transfer Molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional autoclave molding and automated fiber placement for producing large scale structural parts. In VARTM, the fibrous preform is laid on a single sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of resin position and cure on plain weave S2-Glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. The SMARTweave DC sensing system was utilized to conduct parametric studies a) to compare the flow and cure of resin through the stitched and non-stitched preforms, b) influence of sensor positioning, i.e., top, middle and bottom layers, c) influence of positioning of the process accessories, i.e., resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitored from embedded IDEX dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and more superior in terms of obtaining global information in contrast to the localized dielectric sensing approach.

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