Thermal and mechanical responses of fiber reinforced polymer composites under one-sided fire exposure

This research investigated the thermal and mechanical responses of fiber reinforced polymer (FRP) composites in fire. The research focused on thermal decomposition and heat transfer, deformation, delamination, and structural integrity of FRP composites. The research was undertaken by thermal and fire testing, and fire dynamics and finite element modeling.;To simplify the modeling of the decomposition of FRP composites, an infinite-rate pyrolysis model was incorporated into heat transfer modeling to predict the thermal response of the composite panels under one sided heating. The thermal prediction by the infinite-rate model was compared to the finite-rate model, in which the decomposition was described by Arrhenius equation, and was validated with both bench and intermediate scale fire tests. A concept of shift temperature was introduced into the heat transfer to account for the effect of heating rate on the decomposition temperature.;With temperature results given by the heat transfer model, a simplified plane strain model was proposed to predict the mechanical response of FRP composites. Based on a bilinear traction-separation law, cohesive elements in commercial finite element software ABAQUS were incorporated in the mechanical model to consider the effect of delamination for sandwich panels.;In order to evaluate the effect of heat flux of a composite's own flame on its thermal response and fire properties, two-layer flame geometry was proposed to predict the effect of flame heat flux on the thermal response of char-forming materials. The total flame heat flux in a typical cone test was estimated based on general turbulent flame temperature and combustible gas temperature.;All prediction results were validated with experimental data. It was demonstrated that (1) the modeling of decomposition reaction using the infinite-rate model required less input parameters, (2) a material's own flame had significant influent on its fire reaction properties at the beginning of flaming combustion, (3) the plane-strain model was capable of predicting deformation and time-to-failure with a good accuracy, and (4) cohesive elements can be used to model the delamination of sandwich FRP panels in fire.