AFIST

GEM’s Abaqus Fire Interface Simulator Toolkit (AFIST) is a fully coupled fire-structure interaction module within Abaqus for fire response and damage prediction of advanced structures. A direct forcing immersed boundary method (IBM) developed by NIST is generalized and integrated with the current Fire Dynamics Simulator (FDS). A sharp interface characterization of the solid boundary is created and the mapping of the boundary conditions from the interface to its immersed boundary cells is constructed through local interpolation. Heat transfer is treated using a first order method. A kinematic description of the moving boundary is also accomplished via its coupling with Abaqus. A two-way coupling interface between ABAQUS and Fire Dynamics Simulator (FDS) is developed for fire structure interactions.

Coupling between FDS and Abaqus

The coupling framework is developed for data communication between FDS (with IBM) and Abaqus. In this framework, boundary files were generated by FDS and Abaqus, respectively, storing the interfacial properties required for the fire-structure coupling simulation. The format of the data files was defined by both development teams at NIST and GEM so that AFIST, FDS and SmokeView can read them. The flow chat of the two-way coupling scheme implemented in AFIST is shown in the figure below.




Model Generation

To facilitate the model generation, solver selection, and results display within the Abaqus toolkit, a GUI is developed within ABAQUS/CAE. The current features of the AFIST GUI include: 1) generation of FDS and Abaqus model files based on users’ input; 2) definition of model parameters for FDS; 3) definition of structural model parameters for Abaqus; 3) insertion of a coupling interface for co-simulation; and 4) display of co-simulation and fluid structural interaction results. The creation of a structural model can be easily achieved via the existing Abaqus CAE.

To perform a two-way coupling analysis, an interface between the FDS and Abaqus model has to be defined along with the coupling parameters. A structure model can be displayed in the FDS domain with the marked coupling interface.