Papers by Keyword: Energetic Material

Abstract: This work presents a method to estimate probability initiating combustion and detonation by temperature load in void in energetic material. When a void is compressed its volume decreases and the temperature in the void increases. The local thermal source due to the void deformation in energetic material forms a temperature load which may initiate combustion and detonation. The temperature-time history in the void was called temperature load in this work. Its peak value and holding time are the necessary and sufficient condition initiating combustion or detonation of energetic material surrounding the void. Comparing with the energy acted on the unit area of hot spot, the performance of transient temperature which can better serve to reflect the physical essence in ignition. The main object of this work is to study transmitting process of temperature load from void to energetic material and probability initiating combustion and detonation by temperature load in void.

Abstract: GLQ propellant is a new type of energetic material, extensive research indicates that the traditional methods evaluating the stability of this propellant are unsuitable. So in this article, the stability of this material was studied by aging test, methyl-violet test and gas phase chromatography test. The results show that gas phase chromatography test is feasible for evaluating the stability of this material, but methyl-violet test is unsuitable.

Abstract: In order to enforce explosion energy and mechanical strength of energetic material. we use physics and chemistry property of aluminum fire to improve the performance of energetic material. Before explosion the physics property of mechanical property can reinforce the mechanical strength; when explosion the reaction heat of aluminum can increase the energy of explosive. The air blast experimental results indicated that Al fibre can increase the energy of energetic material.. And the same time mechanical strength experimental results indicated that aluminum can enhance the strength of energetic material.

Abstract: Al/Ti multilayer films with bilayer thicknesses of 50nm, 100nm and 200nm were prepared by RF magnetron sputtering alternate Al and Ti layers. The relative thickness of Al and Ti layers was maintained at a 1:1 ratio in order to obtain a 1:1 atomic ratio. XRD measurements show that the compound of AlTi is the final product of the exothermic reactions. DSC curves show that the values of heat release in Al/Ti multilayer films with bilayer thicknesses of 50nm, 100nm and 200nm are 457.99 J∙g^-1, 493.42 J∙g^-1 and 696.81 J∙g^-1, respectively. The exothermic reaction in Al/Ti multilayer films lead to more intense electric explosion. Al/Ti multilayer bridge films with modulation period of 50nm explode more rapidly and intensely than other bridge films because decreasing the bilayer thickness results in an increased reaction velocity.

Abstract: In order to get better interior ballistic performance of deterred-coating propellant charge (DCPC), the simulated annealing algorithm optimization of DCPC carries out in this paper. The interior ballistic model of DCPC and its model of simulated annealing algorithm optimization are established based on the characteristics of deterred-coating propellant. Two key parameters of DCPC, the mass ratio of deterred-coating propellants to total propellants and the average perforation pressure of deterred-coating propellant，are optimized for the search of the maximum muzzle velocity under the restricting conditions of maximum chamber pressure and the maximum relative end point of combustion. The optimization results agree well with the standard charge parameters, which justifies the feasibility of the model.

Abstract: 171 propellant is a new type of energetic material, extensive research indicates that the traditional methods evaluating the stability of this propellant are unsuitable. So in this article, the stability of this material was studied by aging test, methyl-violet test and gas phase chromatography test. The results show that gas phase chromatography test is feasible for evaluating the stability of this material, but methyl-violet test is unsuitable.

Abstract: By means of a tensile instrument and SEM, the mechanical property parameters of HTPB propellant test samples with different formulas were tested, and their microscopic fracture cross section patterns were observed. Take advantage of these testing results, the relationship between microscopic structure and mechanical properties of HTPB propellant was studied. The results show that the mechanical properties of a propellant are closely related to its microscpic structure state. The structural integrity of propellant is mainly influenced by the bond effect of the interface between binder and solid particles, solid particle’s shape, size and its distribution, the content of binder matrix, etc. These factors have important effects on the mechanical properties of propellant.

Abstract: We present results from molecular dynamics simulations of shock-induced hydrodynamic void collapse in a model energetic crystal. During void collapse, hotspot formation is observed that leads to subsequent detonation. The hotspot formation mechanism is identified as shock energy focusing via jetting. There is another initiation mechanism that arises from the interaction of reflected shock waves with the rigid piston, which is considered to be an artifact. Such artifact can be eliminated by altering the location of the void. The detonation threshold as a function of the velocity of the driven piston is determined for various void geometries. It is found that a system containing a void has a lower detonation threshold than that of a perfect energetic crystal. The amount of reduction of the detonation threshold depends on the geometry of the void. For square voids, there exists a minimum size above which reduction of the detonation threshold occurs. Among voids that have an equal volume, the void that is elongated along the shock direction gives the lowest detonation threshold.

Abstract: We present an innovative method of multi-physics application involving energetic materials. Energetic materials are related to reacting flows in extreme environments such as fires and explosions. They typically involve high pressure, high temperature, strong non-linear shock waves, and high strain rate deformation of metals. We use an Eulerian methodology to address these problems. Our approach is naturally free from large deformation of materials that makes it suitable for high strain-rate multi-material interaction problems. Furthermore we eliminate the possible interface smearing by using the level sets. We have devised a new level set based tracking framework that can elegantly handle large gradients typically found in reacting gases and metals. We show several work-in-progress applications of our algorithm including the Taylor impact test, explosive venting and additional confined explosion problems of modern interest.

Abstract: Experiments on combustion synthesis for the Ti-2B and Ti-C systems diluted with an inert metal are presented. The paper shows the influence of geometry, composition, density and particle size of diluent on the combustion front velocity. A Ti-2B reactant mixture diluted with Al and Cu and a Ti-C reactant mixture diluted with Al are studied. The metallic diluent and its concentration are varied. Besides, each experiment is based on a stack of cylinders with decreasing diameter in order to vary the heat losses. In some experiments the eventual quenching of the combustion reaction has been observed. Furthermore these experimental results are compared with theoretical calculations based on analytical expressions derived for such systems.