Fire Structural Modeling of Polymer Composites with Passive Thermal Barrier

A coupled thermo-mechanical model is presented for calculating the compressive strength and failure of polymer laminated composites with thermal barrier when exposed to fire. Thermal barriers are used to protect composite structures from fire, and this article presents a model for calculating the improved structural survivability under compression loading. The thermal component of the model predicts the through-thickness temperature profile of the composite when protected from fire using a passive thermal barrier insulation material. The thermal analysis is coupled to a mechanical model that calculates the loss in compressive strength with increasing temperature and heating time. The model predicts the strength loss and failure time of an insulated composite supporting a static compressive load when exposed to fire. The accuracy of the model is evaluated using failure times measured in fire-under-compression load tests on a woven E-glass/vinyl ester composite protected with a passive thermal barrier. The model predicts reductions to the failure time with increasing heat flux (temperature), applied compressive stress, and reduced insulation thickness, and this is confirmed by experimental testing. It is envisaged that the thermo-mechanical model is a useful analytical method to design thermal barrier material systems to protect composite structures exposed to high temperature or fire.