فصلنامه مواد پر انرژی
سال پانزدهم شماره 4 (پیاپی 48، زمستان 1399)

In this study, an efficient and green technique based on ultrasound-assisted extraction was developed for separation and determination of some components of double base solid propellant (DB propellant) by high performance liquid chromatography with UV detection (HPLC-UV-Vis). The optimum extraction conditions with respect to maximum recovery for target analytes were achieved at 120 min, with the power of 800 W for ultrasonic waves and dichloromethane as an extraction solvent for 0.5 gr of DB propellant sample and the recoveries for all component was near to 100%. The results of this investigation under optimum conditions were compared with the result obtained by the Soxhlet extraction method as a routine sample preparation method for DB propellant samples. The results show that the developed method is much faster and sufficient than the traditional Soxhlet extraction method. So, the developed UAE-HPLC-UV method can be used as a rapid and sensitive method for the determination of DB propellants’ constituents.

In this paper, the effect of an energetic imidazolium ionic liquid plasticizer (ILP) on the degradation kinetics of nitrocellulose, which is a important component of double based solid propellants, is investigated. For better comparison, diethyl phthalate (DEP) plasticizer, which has a structure similar to ILP, was also evaluated. Heat of combustion analysis was performed to evaluate the energetic ILP plasticizer. Enthalpy of combustion for synthesized ILP and DEP plasticizers were respectively 7269±1% and 5468±1% cal/g. Then thermal analysis was performed for NC and NC/Plasticizer blends with 20% by weight of ILP and DEP plasticizers at different heating rates. In this study, DSC analysis was used to evaluate the compatibility of plasticizers with NC. The results of DSC analysis for NC/plasticizer blends showed that NC is well compatible with DEP and ILP plasticizers. The ILP plasticizer was more compatible with NC because its glass temperature was lower. Calculated activation energy, reaction rate constant, thermodynamic parameters and other thermal parameters of NC with 12% nitrogen content and NC/plasticier blended by Kissinger, Starink and Ozawa Flynn-Wall (OFW) kinetic methods. The calculated results were in good agreement with each other in different methods. The results of the calculations showed that the ILP plasticizer did not cause much change in reducing the Critical temperature for the thermal explosion. Degradation activation energy (α = 0.5) using the Ozawa Flynn-Wall method for pure NC, NC-DEP and NC-ILP blends ILP were respectively 145.62, 139.09 and 119.36 kJ/mol

Solid propellant systems are basically two types: case bonded and cartridge. Liner, as a polymeric glue, is responsible for bonding propellant to casing in case bonded ones, therefore, it must have sufficient mechanical and adhesive strength. The type and amount of each component of polymeric composition plays an important role in liner strength. In this research, effect of chain extender content (4-6 percent) and fillers (9-17 percent) on tensile strength of liner based on HTPB and bonding strength of liner-propellant was investigated. The result showed that with increase in amount of chain extender, bonding strength between liner and propellant, tensile strength and elongation at break liner was increased. In addition, it was found that increase in fillers content up to 15 percent improve tensile strength and elongation at break, whiles increase in fillers, decrease bonding strength through decrease in permeability of liner into propellant surface.

When dealing with research and development of the gun propellants, a less expensive, quicker and safer process of the closed vessel evaluation adopted can be used rather than the gun firing test. In the current research work, a computer program (BRCBADR) has been developed for in order to obtain the burning rate reduction coefficients from the closed vessel test data. Correct The correct determination of the thermo-chemical properties of the propellants provides accurate results of interior ballistics analysis. The BRCBADR code has been developed based on a zero dimensional model for evaluating pressure history of burning propellants in a the closed chamber. A new curve fitting method based on the shooting Shooting algorithm is used to calculate burning rate coefficients. In this program, the experimental values of impetus and co-volume have determined from the Noble-Able equation of state. The results of present code are in well agreed agreement with the results of other validated codes. Using of burning rate calculation method has resulted in accurate muzzle velocity prediction (less than one percent error) from 122 mm gun firing. The results of This this research showed that,exhibited the regardless of slivering effects during the burning of seven perforated cylindrical grains, while resulted tothe additional unreal impulse is applied to the projectile.

Conventional analysis and design of reinforced concrete beams under blast load requires a long process. In addition to being time consuming, this method does not determine the extent of the influence of the geometric parameters of the beam and the load. To overcome this problem, in this research, the effect of each parameter is investigated using the mathematics response surface method (RSM) and a direct relation is provided to calculate the beam deflection. A large number of reinforced concrete beams under different explosions were examined in finite element software. The proposed finite element model was validated by a reliable experiment. The rises obtained from reinforced concrete beams were evaluated as input in Design expert software in four models. In each of these models, a relationship was obtained as the beam deflection relationship. By evaluating each of these relationships, the results showed that the cubic RSM model provides the highest accuracy for the beam deflection.

Nowadays, with the increase of the terrorist attacks around the urban places, the building design under the blast loadings is of primary considerations, especially for some important buildings and vital arteries. When an explosion occurs, the blast waves can cause severe damage to the structure and endanger the lives of people. Since the existing steel structures are usually designed for the typical gravity and seismic loads, it is necessary to investigate their performances under blast loadings. In this study, analytical studies have been done for 2D structural models of simple steel frame system with concentrically bracing (CBF) with different number of stories 5 and 10 under blast loading. The nonlinear dynamic method is applied for analyzing and designed the studied models in SAP 2000 software according to UFC 3-340-02 instructions for blasting 1000 kg of TNT at a distance of 20 meters from the structure. Each of the structural models in this study is analyzed and designed by performance-based design method for three levels of high, low, and very low performance. Finally, the designs results from the performance method at different levels are compared in terms of economics and safety.