Tension modelling and testing of sandwich composites in fire

A thermal–mechanical model is presented for calculating softening and failure of flammable sandwich composites under combined tension loading and one-sided unsteady-state heating by fire. The thermal model calculates the temperature rise of the sandwich composite when exposed to fire. The mechanical model computes the reduction to the tensile modulus and strength of the laminate face skins caused by thermal softening of the fibre reinforcement and polymer matrix and weakening of the core. The numerical accuracy of the model was assessed using data obtained from fire structural tests performed on a combustible sandwich composite consisting of thin woven glass–vinyl ester laminate skins and a thick core of balsa wood. Tests were performed at different tension stress levels and heat fluxes. The model can determine the temperature rise, tensile failure stress and failure mechanism of the sandwich composite in fire. The experimental results presented in the paper also provide new insights into the structural survivability of tension-loaded sandwich composites in fire.