An investigation of a surface-burn of the shock-induced decomposition initiation and detonation of heterogeneous explosives is described. The model assumes a microscale process with hot spots ignited by viscoplastic heating at the boundaries of collapsing pores. A relatively thin reaction zone, or burn surface, is driven by the conduction of the heat of reaction, and has a surface-burn velocity with an Arrhenius dependence on the temperature of the unreacted solid component. Global reaction rates are derived from the microscale model with an empirical burning topology function and a macroscopic reactant-product mixture defined by pressure equilibrium, ideal mixing of specific volume and internal energy, and isentropic response of the unreacted constituents. With simplifying assumptions, the model is extended to treat multi-component explosives. The model is implemented into a method of characteristics hydrocode and shown to be effective in simulating several examples of initiation experiments on TATB explosives. 10 refs., 9 figs.

Major advances, both in modeling methods and in the computing power required to make those methods viable, have led to major breakthroughs in our ability to model the performance and vulnerability of explosives and propellants. In addition, the development of proton radiography during the last decade has provided researchers with a major new experimental tool for studying explosive and shock wave physics. Problems that were once considered intractable – such as the generation of water cavities, jets, and stems by explosives and projectiles – have now been solved. Numerical Modeling of Explosives and Propellants, Third Edition provides a complete overview of this rapidly emerging field, covering basic reactive fluid dynamics as well as the latest and most complex methods and findings. It also describes and evaluates Russian contributions to the experimental explosive physics database, which only recently have become available. This book comes with downloadable resources that contain— · FORTRAN and executable computer codes that operate under Microsoft® Windows Vista operating system and the OS X operating system for Apple computers · Windows Vista and MAC compatible movies and PowerPoint presentations for each chapter · Explosive and shock wave databases generated at the Los Alamos National Laboratory and the Russian Federal Nuclear Centers Charles Mader’s three-pronged approach – through text, computer programs, and animations – imparts a thorough understanding of new computational methods and experimental measuring techniques, while also providing the tools to put these methods to effective use.

This paper discusses a new approach to building mechanistic models for shock ignition and other reactive phenomena in heterogeneous solid explosives. In the proposed approach, hot spots are treated on a unifying framework (a hot-spot cell) to integrate the three, principal response behaviors of heterogeneous energetic materials: energy localization (hot-spot formation), temperature dependent chemical reactions, and heat flow. Hot spots are treated statistically through use of a size distribution and its evolution equation. Chemical reactions start at the surface of hot spots, and the products in turn become reactants for the subsequent bulk reactions. A heat conduction equation is solved for the temperature states in the hot-spot cell. Ignition and growth of the reactive burn depend on the complex interactions of the three processes: localized energy deposition, chemical reactions (surface as well as bulk), and heat flow. Coupling of the hot-spot model to hydrodynamic flow equations is based at present on a single cell, using mass averaged mixture equations of state and a common particle velocity for the constituents. The overall model is implemented on a two-dimensional Lagrangian code called CASH. To demonstrate the predictive capability of the model, we show several exploratory calculations using RDX as a model material. They include (1) shock ignition and growth-to-detonation, (2) quenching, and (3) curved detonation in a cylindrical specimen.