Microscopic modeling of ignition and burning for well-arranged energetic crystals in response to drop-weight impact
Yanqing Wu (Beijing institute of Technolog)
Dynamic Behavior of Materials
Tue 9:00 - 10:30
Salomon 101
It has long been recognized that during impact of energetic crystalline solids, some form of energy localization must occur to focus the impact energy into hot spots. However, it was insufficient to obtain just the energy required to cause ignition of an individual hot spot. The present study was concerned with not only this ignition process, but also the subsequent burning stage, both of which are relevant to the possible occurrence of explosion. A micromechanics theoretical approach was developed, to model hot-spot formation and growth to burning for a single layer of energetic particles under a drop-weight loading. To provide supporting evidence for the theoretical model, finite element numerical simulations were carried out to probe into the whole thermo-mechanical interaction processes among the well-arranged energetic crystals. Once hot-spots ignition occurs, the macro-kinetics of chemical reactions can be determined by hot-spots density, combustion wave velocity and geometric factor. Considering the micro-particle plasticity, frictional heating, melting, fracture, and chemical reaction at particle level, effects of loading parameters and sample characteristics on ignition and burning were discussed. The resulting reaction may or may not develop into a violent event, may be sustained or be extinguished, which can be predicted by the present model. Visual information obtained by high-speed photography and measured pressure-time data using our self-established experimental device are used to validate the calculated results.