Hybrid Progressive Damage Prediction Model for Loaded Marine Sandwich Composite Structures Subjected to a Fire

The risk of fire, and of fire-related structural degradation, represents an ever present challenge to the safe design of marine sandwich composite structures. Current state-of-the-art fire analysis and damage assessment tool has ignored the coexistence of discrete (delamination) and continuum damage in a sandwich composite structure after a fire exposure. To capture the synergistic interaction between the discrete and continuum damage and their compounding effects to the final failure, a fire damage assessment tool for a marine composite sandwich structure was developed by integrating the 1D fire model of a composite sandwich panel with a hybrid progressive damage prediction module within the LS-DYNA3D computational framework. The 1D fire model for a combustible skin and decomposable core was employed to characterize the temperature and mass dependent heat conduction, energy consumption resulting from the decomposition, and the energy transfer associated with vaporous migration. For a given thermal and mechanical damage of a sandwich composite system, a multi-scale solution framework was formulated to determine the material response and failure at the structural level from the damage progression at its constituent, ply, and laminated plate level. The delamination failure along an interface was characterized by a cohesive element approach with a user-defined cohesive law while the diffuse damage resulting from the fiber/tow/matrix failure in the sandwich composite was characterized using a continuum damage model. A loaded sandwich beam with and without a fire was considered to demonstrate the effects of fire damage on the ultimate strength of the sandwich structure.