JOURNAL OF ENERGETIC MATERIALS
Year:2020 | Volume:15 | Issue:2 (46)|Papers Count:6

Shelf life prediction for liquid fuels depends on a reliable and efficient accelerated ageing method. Most of the available researches in this area are limited to isothermal ageing. Therefore, these isothermal ageing methods are not capable to predict shelf life for fuels at non-isothermal ageing conditions. In the previous work, a new approach called reaction severity index was proposed for the prediction of liquid fuels shelf life at isothermal aging behavior and the results of this approach compared with classical Arrhenius one. In this work, at first this approach has been used to predict the Samine fuel shelf life at alternate temperature cycles of 50 and 60 ° C. The predicted shelf life based on Arrhenius and Berthelot reaction rate are 104. 3 and 106. 2 days, respectively that shows a good agreement with the empirical value of 110 days. Then the fuel shelf life was predicted using different temperature patterns. The results showed that the Berthelot approach predicts lower values of shelf life rather than the Arrhenius approach at ambient temperatures, while at higher temperatures the predicted values are approximately the same. Ultimately, the predicted shelf life at temperature patterns of 20, 60, 30, 60, 4, 60, and 50, 60 ° C showed that the predicted shelf life of all patterns are in the vicinity of the fuel shelf life at 60 ° C. Therefore, the reliability of this approach makes it possible to predict the fuel shelf life for storage conditions at ambient of non-isothermal temperatures.

2-Azido N, N-Dimethyl Ethane-1-Amine, well-known as a DMAZ, is considered as a new green liquid fuel and a good alternative to hydrazine fuels because of its high performance while being non-carcinogenic. But no DMAZ energetic complex has been synthesized and reported yet. In this study, a new energetic complex of copper(II) nitrate and DMAZ ligand was synthesized for the purpose of increasing the density of this ligand by metal-coordinating at two nano and bulk scales (with the medium particle size, 54. 6 nanometers, and 45. 33 micrometers, respectively). These synthesized complexes were characterized by FT-IR, UV-Vis, and fluorescence spectroscopy methods and the molar ligand-to-metal ratio was obtained by Job and Mole fraction methods. Their thermal decomposition behaviour have also been investigated. The results showed that changes in particle size led to changes in thermal behavior and energy released from these complexes (480 J/gr).

In recent years, with the increasing number of terrorist attacks and explosions in structures, extensive studies have been carried out on the performance of structures and their reactions under blast load. Due to the importance of the pile in the load transfer of various structures such as wharves, oil platform and bridges it is essential to study the behavior of this member. In this research, to minimize the damage caused by the blast load and the waves caused by the blast, the behavior of steel piles in two types of loose and dense sandy soil was investigated by Abaqus. The modeled pile is placed under different blast loads at 5 m distance from the pile head (at the soil surface) and the end of the pile (at the soil depth) has been studied. Finally, it was observed that the bending moment pile in dense sandy soil was significantly more than bending moment pile in loose sandy soil. The horizontal displacement of the pile head when the blast occurred at the soil surface is far greater than the displacement of the pile head under the blast load.

In addition to performance requirements, safety aspects for production, transportation and storage are very important for explosives because involuntary instantaneous explosion can causes irreparable financial losses and casualties. Ability of explosives for response to the stimuli such as impact, friction, shock wave, flame and heat is called sensitivity and is a key factor in determining the practical application of an explosive material. For decreasing of the sensitivity of explosives with maintained efficiency, it is necessary to use desensitizer. For this purpose, waxes, polymers, or a mixture of waxes and polymers can be used. In this research, industrial wax parameters in explosives such as melting point, congealing point, softening point, insoluble organic matterials, percentage of exudation, acidity, alkalinity, flash point, needle penetration, oil content and Differential Scanning Calorimetry (DSC) for three wax samples were determined by the credible standards. Finally, the results of parameters were analyzed.

The electric initiator is an important component of the explosive train which provides requiered energy to initiate a chemical reaction by converting the electric current to the heat via a bridgewire. This initiator is widely used in the field of aerospace industry in the solid rocket propellant motors, separation systems and etc due to its low weight and high reliability. In this research, a mathematical model has been introduced to investigate the effective parameters on the electric initiator performance. Comparison of numerical simulation results by finite difference method and experimental data showed that this model has the ability of the prediction of the ignition time and determine the transient temperature profile in axial and radial direction. The model showed that the reduction of the contact heat transfer coefficient between the bridgewire and the primer compared to its increase has a greater effect on the heat transfer rate. It was also found that with increasing the current, the temperature changes decreased along the axial direction and increased in radial direction.

In this research, the effect of FRP sheets on the flexural and shear performance of concrete columns of a structure against explosion has been investigated and strength and shear performance of concrete columns reinforced with FRP sheets against explosive loads is evaluated. In order to evaluate the performance of concrete columns against explosion and the effect of their shear reinforcement by FRP sheets, a square column with specific cross-sectional dimensions and a height of 3 meters has been considered. The column was subjected to an explosion of 82 kg of TNT at different distances from the column and was analyzed. The concrete column was reinforced with full sheath using FRP sheets and the results were compared to investigate the effect of reinforcement on the performance of the concrete column against explosion. Then, by modeling a 5-storey concrete building and in two modes without and by reinforcing FRP sheets at the end of the column and the connection fountain, we tried to improve the performance of the concrete building by controlling the shear in these areas. The results show that the use of FRP plates in the concrete column under explosive loading causes a significant reduction in horizontal displacement. This reduction is greater at closer distances, so that at 2. 5, 5 and 10 meters distance from the explosive charge, a decrease of 52. 6%, 32% and 31% of horizontal displacemen have been observed, respectively. Also, the use of FRP causes a large amount of kinetic energy due to the explosion to be wasted in the form of structural damage.