Modelling heat transfer through an FBG optical fibre

This paper presents a new approach to model heat transfer through an optical fibre. Three thermal strain modelling procedures were evaluated for coated and uncoated FBG optical fibres, considering different layers of sensors that effect strain measurements. The compensation factors required for strain measurements were investigated. The acrylate coating was found unsuitable for thermosetting polymers due to low Tg whereas, polyimide coating was appropriate for cure monitoring due to high Tg than most thermoset resins. Three types of thermal strain models were simulated, and the results were compared with experiments. The heat transfer through the core of an optical fibre was found negligible relative to glass cladding and the coating layers. It was found that thermal strains induced by the glass cladding and protective layers become more dominant as the heating rate and temperature range increases. The uncoated FBGs were found to give better accuracy for high temperature applications.