JOURNAL OF ENERGETIC MATERIALS
Year:2018 | Volume:13 | Issue:1 (37)|Papers Count:7

By stimulating Cylotrimethylenetrinitramine (RDX) through exerting temperature or mechanical impact or friction, decomposition reaction occurs at very high rate. Molecular dynamic technique and LAMMPS code with ReaxFF-lg were employed to simulate initiation of RDX. Potential energy variations of the system were calculated over time for five different temperatures up to 3 nanoseconds and the products of decomposed system respect to time were determined at each stage of stimulation for different values of temperature and thermal initiation stimulation energy in NVE and NVT ensembles. The activation energy of decomposition was calculated 24. 13 Kcal. mol-1 through Arrhenius equation. The minimum needed temperature to produce hydrogen molecules with temperature decomposition was about 2500 K and production times for several conditions were calculated. The amount of nitrogen and hydrogen production were increased with raising temperature and reached maximum at 3000 K. Maximum values of nitrogen and hydrogen production were at 3000 K. The time required to complete the decomposition reaction was 2000 picosecond at 2500 K.

Safety evaluation of concrete dam under critical situations such as blast loading has gained importance in recent years due to the great number of accidental events and terrorist bombing attacks. In the present study, the dynamic response of Karun IV double curved concrete dam with considering different reservoir levels under air blast loading has been evaluated. A finite element model of dam-reservoir-foundation system is built using abaqus software. The results show that the water level of the reservoir has significant effect on dynamic response of arch dam and in the full reservoir the required weight of explosive material for failure of dam body is increased 15 persent compared to half full and empty reservoir.

Performance improvement and increasing of penetration of Explosively Formed Penetrators (EFP) is one of the most considerable issues in the field of defense researches. There are various solutions to achieve this purpose, including innovative designs in the field of charge, linear, skin, explosive train, etc. In this paper, the effect of multi-point initiation on the formation and penetration of EFPs is investigated using by finite element method and Ls-dyna code. Furthermore, the simulated model was developed and exprimental tests were performed to measure the penetration depth and hole diameter caused by the impact of EFP to the target of steel plate. Comparison of simulations and experimental results shows good agreement. Also measurements shows the 40% increase of penetration depth in case of multi-point initiation in comparison with single initiation, which can be good result in performance improvement of EFP warhead.

In this research a reactive energetic plasticizer (REP) was synthesized that contain an activated terminal alkyne group and expected to give rise to azide-alkyne 1, 3-dipolar cycloaddition, and prevents the migration of plasticizer to the external surface of polymers. This plasticizer contains an energetic group (ONO2) and increase energetic performance and oxygen balance. Propargyl Terminated Poly Glycidyl Nitrate (PTPGN)) was synthesized and characterized by DSC, GPC, FTIR and 1HNMR. The result of GPC showed that the Mn is about 731 g/mol. The plasticizer has oligomeric structure. DSC thermogram showed that the glass transition temperature is-66. 50C. This plasticizer degraded at 170° C and it´ s degradation take place in two stages.

Aminotetrazoles are derivatives of the tetrazole with unique properties. Although they have high heat of formation, but they show very high thermal stability. Aminotetrazoles have high nitrogen content among organic compounds and are very suitable in Propellant, gas generator and explosive formulation. In this paper, a new energetic and stable compound (5-Amino-tetrazol-1-yl)-acetic acid 2, 2-dinitro-propyl ester that has a ring of tetrazole, was synthesized by esterification reaction with energetic alcohol 2, 2-dinitro-propanol (in order to ncreasing energy and Performance), this compound has 36% N and 859 gr/J enthapy of decomposition and identified with IR and NMR techniques also, the thermal behavior of this compound was studied with DSC technique.

Today, aluminum powder is a widely used in solid propellants, explosives, and pyrotechnics to increase its power. In this study, an analytical investigation of counterflow premixed flame of micro aluminum particles carried out. For this purpose, continuity and energy conservative equations obtained by using of the definition of strain rate for counterflow combustion of metal particles and then analytically solved. Variation of burning rate via particles diameter is obtained and compared with the experimental results of the others references which showed good accurate. Variations of the flame location, flame thickness and combustion temperature with strain rate for deferent particles diameters are presented. Current results showed that with decreasing flame distance from origin and particles diameters and also increasing of strain rate, the flame thickness is decreased. Also it is found that in the counterflow combustion of aluminum particles, the flame location with decreasing the strain rate and the particles diameters moves away from the symmetry wall, combustion temperature increases and location of flame transfers to the higher velocity field of flow.

In this article HTPB based composite solid propellant aging have been studied by Van’ t Hoff method. Since composite solid propellants used in solid rocket motor is the fastest degrading component of the motor, shelf life of the motor is mainly governed by the propellants life. During handling and storage of rocket motor the mechanical properties of propellants are changing due to thermal, environmental, chemical, physical and internal changes. In this study the calculated F-factor was equal 2. 5 by dynamic mechanical analysis on selected formulations of reference propellants sample. Then the accelerated aging program conditions have been determined. According to accelerated aging program the propellant samples subjected temperature range between 25° C and 80° C so that the aging time equal 2 years at 25° C. The evaluated of changes in the dynamic mechanical properties, including the storage modulus (E') and loss factor or damping efficiency (tanδ ) to investigation of behaviour the composite solid propellant aging. The result showed that storage module increased with time whereas loss factor decreased. This phenomenon related to cross-linking density mechanism in polymeric binder system.