Finite element modelling of fire degraded FRP composite panels using a rate dependent constitutive model

A thermal model for the pyrolytic decomposition of FRP composite sandwich panels exposed to fire has been numerically implemented. The degradation of key mechanical properties with elevated temperatures has been characterized. Finally, a constitutive theory for FRP laminated composite materials that accounts for both temperature and strain rate dependent response, as would result from exposure to the elevated temperatures of a fire, has been developed and implemented. The theory fully accounts for arbitrary reorientations of the laminate and anisotropic material response, as well as for finite strains. The mechanical model thus takes into account expected material-level failure modes such as kinking as well as structural modes such as global buckling. In the current work, these three models are tied together, allowing the thermomechanical response of an arbitrary structural member exposed to fire to be characterized. An existing experiment, involving a panel exposed to combined mechanical and thermal loading, is modelled using this technique, and the model is shown to accurately replicate the panel's response.