Velocity and Shape of Explosive Computation using Multi-Material and ALE Formulations (original) (raw)
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Thermal Science, 2016
The research in this paper considered the temperatures fields as the consequently influenced effects appeared by plastic deformation, in the explosively forming process aimed to design explosively formed projectiles. As the special payloads of the missiles, used projectiles are packaged as the metal liners, joined with explosive charges, to design explosive propulsion effect. Their final form and velocity during shaping depend on distributed temperatures in explosively driven plastic deformation process. Developed simulation model consider forming process without metal cover of explosive charge, in aim to discover liner's dynamical correlations of effective plastic strains and temperatures in the unconstrained detonation environment made by payload construction. The temperature fields of the liner's copper material are considered in time, as the consequence of strain/stress displacements driven by explosion environmental thermodynamically fields of pressures and temperatures. Achieved final velocities and mass loses as the expected explosively formed projectiles performances are estimated regarding their dynamical shaping and thermal gradients behavior vs. effective plastic strains. Performances and parameters are presented vs. process time, numerically simulated by the Autodyne software package.
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Journal of Applied Mechanics and Technical Physics, 2013
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A Micromechanic Model for Shock to Detonation Transition of Solid Explosives
We propose a model for the ignition and growth of a detonation in a pressed solid explosive. The ignition is assumed to occur at the pores scale, while the growth stage starts from an inner combustion in the pores and is followed by an outer surface grain combustion. To model this sequence of events, we first develop a model for ignition by viscoplastic pore collapse on the basis of Khasainov 1 and Kang et al. 2 works. The growth stage starts with an inner pore combustion and is described by an extension of this model. The grain combustion model is used for the second stage in the detonation growth. The information at the microscopic scale are then homogenized in a macroscopic model where waves propagation is considered. The macroscopic model is based on the mixture Euler equations with an appropriate EOS. The numerical resolution is performed with a specific front tracking scheme preserving sharp shock front and interfaces.
International Journal of Impact Engineering, 2007
The whole process of formation, flying and penetration of explosively-formed projectile (EFP) is simulated by a 3D coupled hydrocode of Ls_dyna. The caliber of the shaped charge is 60 mm and EFP is a kind of overturned shaped charge. The Arbitrary Lagrangian-Eulerian (ALE) method is adopted to consider the fluid-solid coupling problem. The velocity attenuation equation is fitted to forecast the flight distance of EFP. The penetration property of EFP to the armor plate is studied by similarity theory and numerical simulation. For validating the equation, a test is designed to study the residual velocity after penetrating a 25 mm thick steel plate from a distance of 48 m. Therefore, some important solutions are obtained from the comparison of the simulation and experiment. The solutions are optimized charge structure of EFP, the ideal shape of projectile, the attenuation rule of flight process and the penetration property after 48 m flight. The numerical solution fits the experimental data well and the study results provide important reference to the design of EFP in engineering. r
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Journal of Hazardous Materials, 2005
A simple empirical relationship is introduced between detonation velocity at any loading density and chemical composition of high explosive as well as its gas phase heat of formation, which is calculated by group additivity rules. The present work may be applied to any explosive that contains the elements of carbon, hydrogen, nitrogen and oxygen with no difficulties. The new correlation can easily be applied for determining detonation velocity of explosives with loading densities less than 1 g/cm 3 as well as greater than 1 g/cm 3. Calculated detonation velocities by this procedure for both pure and explosive formulations show good agreement with respect to measured detonation velocity over a wide range of loading density.
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Shock Waves, 2010
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Numerical Prediction on Cookoff Explosion of Explosive under Strong Confinement
Materials Science Forum, 2007
The cookoff of explosives is of great concern for the safety assurance of explosive devices in storage, transportation and handling. It may occur in the situation that explosive devices are subjected to the external heating stimuli such as fire or high-temperature surrounding. In order to gain ever-increasing knowledge toward the cookoff explosion of explosives, we establish numerical program to predict the cookoff explosion of explosive in a metal container. The computational formulation and methods are given in detail. The thermal decomposition and temperature variation in the interior of explosive were found corresponding to several typical external heating conditions. The results demonstrate that the method is beneficial to the future study on this subject.
Numerical simulations of the formation behavior of explosively formed projectiles
Defense and security studies, 2022
Explosively formed projectile (EFP) is a self-forging shape charged structure having very high penetration ability compared to conventional kinetic energy projectile. The penetration capability of an EFP is strongly dependent on various design parameters. The main parameters can be roughly divided into geometric and material parameters used in the warhead configuration. The present research is an effort to study the effect of metal casing thickness, type of metal used for casing, explosive type, liner thickness, type and configuration on the formation of EFP. Effectivness of an EFP is studied in terms of final velocity and shape of formed penetrator. The study is carried out by performing a number of simulations by using explicit finite element (FE) hydrocode ANSYS/Autodyn.
Study of detonation process: numerical approach
Proceedings of the 2nd Conference on European Computing Conference, 2008
This paper is based on non-linear finite element analysis of the effects of the blast wave on structures, caused by the detonation of explosive materials. Dynamic response of a pipeline subjected to the shock wave produced by the detonation of high explosive materials is presented in this paper. Coupled Euler and Lagrange formulation are used in the finite element analysis of such problems to accurately represent the detonation phenomenon. Preliminary results allow for detailed analysis of the blast wave propagation and its influence on the pipeline.
International Journal of Impact Engineering, 2017
Detonations of nitromethane spherical charges have been carried out to study close-in blast loading of steel plates and the effectiveness of several protective solutions. Three types of bare steel plates, namely mild steel, high-strength steel, and stainless steel were subjected to explosive blast loading. Steel plates of the same type with polyurea coating and composite covers were also subjected to localized blast loading. During an explosive field trial, the blast pressures and displacements of steel plates were measured. Additionally, loading of steel plates by the impinging detonation products was captured by high-speed video recordings. This experimental program has produced results which can be used to calibrate numerical models and to refine the simplified models for predicting blast loads and response of structural elements due to close-in detonations. The effectiveness of polyurea coating for enhancing blast protection of steel plated structures is discussed. The engineering-level model for predicting the blast impact impulse of the detonation gases from the charges in close proximity from the target is introduced and validated using the experimental results obtained during the course of the explosive trials.