Thermochemical responses of sandwich panels to fire

Abstract

Glass reinforced plastic (GRP) sandwich panels are increasingly being used in the offshore industry and their behaviour in fire is studied using mathematical and numerical modelling. A mathematical model is developed to analyse the thermochemical response of a widely used GRP sandwich panel, consisting of two glass-fibre/polyester GRP outer skins and calcium silicate (Vermiculux) sandwich material in between. The model accounts for (i) thermochemical decomposition in the GRP skins, (ii) transient heat conduction in Vermiculux and (iii) the effect of thermal contact resistance at the GRP/Vermiculux/GRP interfaces. A numerical model is presented using the finite element technique. A mixed explicit–implicit Bubnov–Galerkin finite element approach is adopted. In addition, a novel implicit method is used to include the effect of temperature drop at the interfaces. The numerical results are presented and comprise temperature profiles. They are compared with some experimental data and discussed. It is shown that GRP sandwich panels offer good passive thermal protection. Thermal contact resistance is important and may reduce heat flow by 13%.