فصلنامه مواد پر انرژی
سال دهم شماره 3 (پیاپی 27، پاییز 1394)

Some mono and di imidazolium-based ionic liquids with dicyanamide were synthesized and characterized. The synthesis of these compoundes were done based on alkylation reaction of N-methylimidazole followed by anion exchange. The structure of novel ionic liquids were identified by using FT-IR, 1HNMR spectroscopies and elemental analysis. Among the synthesized ionic liquids, thermal properties of 1,6- bis(3-methylimidazolium-1-yl)hexane dicyanamide [MIm2C6.DCA2] were studied with thermogravimetry (TG) and differential scanning calorimetry (DSC). Thermal decomposition of this ionic liquid was exothermic and it was thermally stable up to 311 °C. In additional, the ignition delay (ID) of selected ionic liquid was measured by high speed camera. The measured ID for this ionic liquid was 37 ms.

In the present paper, three-dimensional numerical analysis of low-velocity impact of rectangular sandwich plates with fiber metal laminate (FML) face sheets is investigated. In contrast to the available models which have used the approximate plate theories, a 3D finite element simulation is utilized for extracting the impact responses based on the elasticity theory. Finally, the effects of different parameters such as fiber type, metal type, indenter energy, eccentricity and the in-plane preloads on the impact responses of the structure are investigated. Numerical results are compared with the experimental data presented in the literature and the numerical model is verified. The simulation results showed that in the cases of the eccentric impact and presence of the tensile preloads, the contact force increases due to the less movability of the impacted point of the plate; a fact that may lead to higher damages.

Hydroxyl terminated polybutadiene (HTPB) is the most important and versatile binder used in the formulation of composite solid propellant. However, HTPB is an inert binder and immiscible with traditional energetic plasticizers. In this research, two types of energetic plasticizer, 2-ethylhexyl nitrate (2EHN) and 2-ethyl-2-buthyl-1,3 dinitrate propane (EBDP), which have C /-ONO2 ratio greater than 4 are synthesized and characterized by FT-IR and 1H NMR. Performance of these compounds as energetic plasticizer have been investigated by measuring their heat of decomposition, heat of combustion, glass transition temperature and heat of formation. In addition, the compatibility of the selected plasticizers with HTPB, have been evaluated by calculation of Hansen solubility parameter and measurement of glass transition temperature (Tg) by differential scanning calorimeter (DSC). Low value of miscibility parameter (Δδ) and appearance of a single glass transition Tg is a reason for miscibility of the plasticizer in HTPB and formation a homogeneous binder/plasticizer system. Furthermore, the viscosity measurement of resin in different weight percent of plasticizer have shown that the equal mixture of two plasticizers provide the best results for process ability of resin.

Propellants are decomposed slowly during storage. So each propellant has useful life time which more than that time propellant is not safe and cannot used. Tracing of propellant stabilizer consumption is one of the important methods for determination of storage life time period of a propellant. In this article by accelerated aging on a double-base propellant and then chemical extraction of stabilizer, Tracing of propellant stabilizer consumption is done. Kinetic models which used are zero order, First order, Second order, NATO method and Bertholet. Then kinetic parameters of aging reaction and storage life time of propellant for 50% consumption of stabilizer by different methods are estimated Finally predicted lifetime for Zero order, First order, Second order, NATO method and Bertholet are 58, 45, 35, 31 and 14 years respectively.

In this paper, the plastic deformation of clamped rectangular steel plates is investigated both experimentally and numerically using gases mixture detonation approach. In this series of experimental tests, the steel plates with various thicknesses were deformed under shock wave effect which had been caused by high velocity rate explosion. Also, the pressure of gases mixture detonation was measured after detonation by piezoelectric pressure transducer. The experimental results related to effect of parameter such as the percentage of gas mixture, plate thickness and boundary condition on longitudinal, transverse and diagonal strain distribution were presented. The numerical simulation is carried out using the finite element analysis software ABAQUS/Explicit. To validate the numerical simulation, the obtained results of simulation were compared with experimental ones. This comparison demonstrates that the numerical results have satisfying compatibility with experimental results. In general, all data is in the reliable range. Hence, utilizing the mentioned numerical model is appropriate for predicting the deformation profile and also the midpoint deflection of rectangular steel plate.

Explosive powder compaction is one of the developed methods of powder metallurgy that has been investigated due to the limitations of the traditional powder metallurgy. In the process in order to achieve higher density, instead of pressing force the energy released by the explosion of an explosive is used to compact and sinter the powder simultaneously. Explosive powder compaction can be done by the two main methods, direct and indirect. In this paper, within the introduction of different methods of explosive powder compaction and the history of conducted researches, Simulation has been operated with AUTODYN software to simulate the forming procedure of the Al-B4C powder, and the effects of the mass ratio of explosion to powder and water layer thickness on the created pressures in the powder ambient was presented in pressure-time diagrams. Next, some discs were made from the mentioned powder by the explosive method, and their density was 99% of theoretical density.

Aluminum powder is a common ingredient in energetic materials. Reactivity of this metal can be improved by reducing the particle size, due to their larger surface/volume ratio. In this research, the effects of using nano-structured aluminum powder investigated on physical, thermal, mechanical and explosive characteristics of an HMX-based PBX. The results indicated that the experimental density increased up to 2.5 percent by replacement of the nano-structured aluminum powder instead of micronized aluminum. It has also shown that this replacement caused to the hardness and tensile stress enhanced to 18 Shore D and 0.67 MPa, respectively. On the other hand, the elongation at maximum stress decreased from 10.5 to 9.8 percent. Furthermore, a catalytic effect has been shown in phase transition and self-decomposition temperatures of HMX in DSC analysis. This catalytic effect increased the impact sensitivity of composition up to 7.7 percent. Based on comparative dent test, it is established that the nano-structured aluminum powder has no considerable effect on detonation characteristics of PBX charge.