Modelling of glass fibre-polymer composites with surface protection against fire

This paper presents a new modelling approach to analyse the fire structural response of fibreglass-polymer composites protected with an insulation surface layer consisting of thermally passive or active (intumescent) material. The model is designed to predict the temperature, decomposition, softening and failure of fibreglass composites protected from fire with either a passive or active surface coating. The modelling involves a multi-stage analytical approach: (i) thermal analysis of the surface coating (including decomposition and expansion in the case of the intumescent material), (ii) thermal-chemical analysis of heat transfer through the composite substrate (beneath the surface coating), including decomposition of the polymer matrix and softening of the fibreglass reinforcement, and (iii) thermal-mechanical analysis of the failure of the composite under tension or compression loading. Fire structural tests were performed on a woven glass/vinyl ester composite protected with either a thermally passive insulation (ceramic fibre) or an organic intumescent coating to validate the modelling approach. It is shown the model can approximate the thermal insulation provided to the composite substrate by the surface coatings. The model can also approximate the temperature, softening and failure of the fibreglass composite substrate with a passive or intumescent surface coating.