VFM (Vehicle Fragmentation Model) provides an assessment of the thermomechanical break up events for complex geometries, composed of two or more components linked by joints. In doing so, it enables the evaluation of vehicle fragmentation at more than the prescribed altitude criteria provided by other engineering re-entry codes. VFM is designed to be integrated into the Re-entry Casualty Risk module, facilitating the end-to-end evaluation of re-entries.

  • Failure Modes - Fragmentation can be triggered by a number of thermal and mechanical processes as well as standard destructive re-entry code criteria. The available failure modes are:
    • Predefined altitude for catastrophic failure
    • Selectable dynamic pressure for joint failure
    • Predefined temperature for joint failure - this buckling temperature is not restricted to the material melt temperature
    • Buckling stresses on an individual component
    • Bending moments on joints between components
    • Thermal stress failure due to differential thermal expansion between materials.
    Each of the mechanical failure modes accounts for the weakening of the structure as the temperature is elevated during re-entry.
  • Extensible - Interface definitions are provided for all key components, permitting clients to construct particular heating models optimised for their specific material behaviour, including ablators and meteorites.
  • Configurable - All aspects of VFM can be configured using JavaScript. This enables the selection of fragmentation mechanisms, and thresholds, without resorting to changes in the core engineering simulation.
  • Portable - Written in a combination of Java and JavaScript, VFM is fully supported on Windows, Unix / Linux and OS X.