Integrated FBG sensor responses and full field thermo-electric stress approach to monitor damage accumulation in glass fibre reinforced composite plate

Monitoring internal damage status of advanced composite components with distributed sensor network has shown significant success in recent research works. However, application of such a system in a full scale structure is a critically challenging task and maintaining such a system during life time operations is an extremely difficult. An additional non-contactable full field strain measurement system being used to measure outer surface strain field of a composite sample while an embedded FBG sensor closer to an internal void being used to monitor localized strain variation. Recent developments in miniature low-cost microbolometer technology have paved the way to use full field thermo-elastic stress mapping using relatively inexpensive Infra-Red cameras. This paper details a comparison of strain measurements observed from FBG sensors embedded in a composite plate sample at a closer location to a void and full field thermo-elastic stress map. The test coupons were fabricated with a purposely created delamination and sample was loaded by quasi-static and low cycle fatigue uni-axial loads. The FBG responses and IR images were recorded in frequent intervals in order to track the delamination growth. Further the strain variations were studied using a detailed FEA and compared with experimental strain and full field Thermo-elastic stress map.