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Andrews, Stephen Arthur

Publications and source records attributed to Andrews, Stephen Arthur.

Verification and validation of detonation-shock-dynamics relations for explosives described by general equation of state and chemical reaction models

Detonation shock dynamics is a powerful method to model the behaviour of High Explosives (HE). However in order to use this method, the underlying relationship between the local radius of curvature and the detonation speed must be known. Previous work has developed methods to calculate this effect using simple, single-step Arrhenius and polytropic gas, models for the chemical reaction and the equation of state, respectively. In recent years, more complex models for both reaction rates and equations of state have been developed which show better agreement with experimental data than these simple models, especially when considering condensed phase explosives.. This work presents the governing equations for solving these problems in a way that is generalised to use arbitrary equations of state as well as reaction models which may have more than a single step and multiple product species. This implementation is verified against exact solutions, demonstrating that the equations were implemented properly. The verified algorithm is then validated against experimental data and high fidelity simulations, showing that it is able to make accurate predictions in a regime where the underlying assumptions of the governing equations are valid. Importantly, this approach has many applications: from creating equivalent detonation shock dynamics models for existing reactive burn calibrations for HE; to developing new functional forms and calibrations of reactive burn models for condensed phase high explosives.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Overdriven Shocks: Recapturing a Lost Capability

Wallace’s theory for overdriven shocks in solids provides a theoretical framework for the strength of materials in the strong shock regime at strain rates unobtainable by current experimental means. Using irreversible thermodynamics, this theory incorporates heat and plastic flow as dissipative mechanisms under shock conditions allowing for the calculation of properties such as deviatoric stresses, plastic strains, and plastic strain rates. Though the theory is over four decades old, it has been used to calculate the strength behavior of only a small handful of metals. In this work, we have recaptured the ability to conduct this analysis, and two crucial aspects of the overdriven theory will be discussed: 1) the modeling assumptions that comprise this theoretical approach and 2) what information is needed to calculate the strength behavior for new materials.

36 MATERIALS SCIENCE↗