Fiber optic sensors for monitoring flow in vacuum enhanced resin infusion technology (VERITy) process

Today, with cost becoming a very important factor, alternate processes for manufacturing composite structures, wherein the cost can be reduced but having similar properties to prepreg systems are being explored. National Aerospace Laboratories, India is developing the VERITy process, which is essentially a hybridization of the VARTM and the autoclave moulding process. One of the concerns in this process, especially when making large integrated co-cured structures with varying thickness, is the knowledge of the resin flow front location at all times. A network of flow-sensors, which could provide information on the flow front location, would be very useful. This paper discusses the experimental studies carried out towards the development of a flow-sensor in the optical domain to determine the presence of resin qualitatively. Three different approaches have been attempted to detect the arrival of the resin flow front and these results are presented.