UC San Diego

The goal of this work is to predict the mechanical behavior of FRP composite sandwich structures in naval applications during a fire event. To do this, several models have been developed and integrated. The first is a thermal model---this provides a prediction of temperatures with time resulting from the fire exposure; accounting for heat transfer, the thermal decomposition of the resin, and the resulting mass transfer. These temperatures are then used with mechanical property degradation relations to determine degraded mechanical properties as a function of time. The predicted temperatures and mechanical properties can be used to determine a temperature-dependent coefficient of thermal expansion, and as well to predict thermal deflections. A material model has been developed that adequately represents the elastic-viscoplastic mechanical behavior of laminated FRP composites, and can exhibit all relevant failure modes. Finally, an implementation of this material model within a finite element code, with material properties degraded element-by -element, is used to predict structural behavior. In addition to the complete description of this process, several other things are included to develop it further. The use of naval composites is described in some detail, along with relevant code requirements. The general behavior of FRP composites in fire is discussed. Following development of each model, relevant parameters for use within the model are provided. For the thermal model, the model is further characterized statistically---i.e., sensitivity analyses and uncertainty analyses are performed upon it. Validation/verification of the various models is also discussed