فصلنامه مواد پر انرژی
سال هفدهم شماره 1 (پیاپی 53، بهار 1401)

Resistance to explosive loads is one of the most important aspects of the design of critical structures due to the wide range of threats. With the widespread use of concrete in the development of explosion-resistant structures, there is much research on the response of concrete components against dynamic loads such as explosion and impact in the technical literature. This paper experimentally and numerically investigates the simultaneous effect of increasing the density of concrete and reinforcing it with hooked-end steel fibers against blast caused by the high explosive pentolite mixture (C-4). In this regard, a total of 150 cubic and cylindrical concrete specimens containing steel fibers in different volume fractions (0, 0.5, and 1%) were made to evaluate the physical and mechanical properties of normal-weight (NW) and heavyweight (HW) concrete. After examining the NW and HW concrete mix designs in the laboratory, blast field tests were conducted by directly attaching the explosive on a set of six concrete blocks with dimensions of 50×50×10 cm fabricated with optimal mix designs of both concrete types. Subsequently, numerical modeling of the concrete behavior against blast load was performed using LS-DYNA finite element software to validate the examined parameters, and then the modeling output was compared with laboratory and field results. The results obtained from the finite element modeling indicate an acceptable agreement with field observations and laboratory results

In this work, a simple and selective method for the determination of nitroglycerine (NG) in double base solid (DB propellants) has been developed and validated. The proposed method is based on alkaline hydrolysis of NG and followed by colored reaction of released nitrite ion with p-nitroaniline in the presence of diphenylamine in acidic media, producing azo dye. The effect of important parameters on the solution absorbance was investigated and optimized. Under optimal conditions, at λmax= 534 nm, the linear range of determination of nitroglycerine was 0.2-5.0 µg mL-1 with detection limits of 0.1 µg mL-1. The proposed method was successfully applied to the determination of nitroglycerine in DB propellants with good recoveries ranged from 98-105 % and RSD less than 2.5 %. the results were statistically compared with those obtained by the by military standard 286 method using t- and F-tests. There was no significant difference between the mean values and the precisions of the two methods at the 95% confidence level. The results showed that the proposed method offers an accuracy and reliable approach for the determination of nitroglycerine in DB propellants, and can be suggested as a routine method in military quality control laboratories.

Being non-polar and considerably high electrical resistivity are significant drawbacks of the crystalline paraffin wax used for desensitizing energetic materials. Herein, as a practical approach to improve the wax properties, maleic-anhydride was reacted with paraffin wax in the presence of a free-radical initiator. Then, the reaction success was approved by employing Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) to spot carboxyl groups onto the aliphatic backbone. In addition, the thermal properties of the modified wax were investigated using differential-scanning-calorimetry and thermogravimetry analysis (DSC-TGA). Finally, to estimate the improvement in the wax polarity, an experiment was designed in which HMX coated via a two-step procedure was conducted for DSC and tribocharing tests. The second layer utilized 0.5 w% glyceline as a deep eutectic solvent (DES). In brief, our observation exhibited that the modified wax caused a 50% decrease in charge accumulation compared to the unmodified paraffin. In addition, our experimental outcomes .showed that the modified paraffin exhibited a better distribution over the substrate surface than the unmodified one.

The study of the simultaneous impact of earthquakes and explosions on structures has been considered by researchers in recent years. On the other hand, irregular effects in structures lead to increased complexity in predicting the behavior of structures. Thus, in this article, for the first time, the simultaneous impact of earthquakes and explosions on irregular structures is investigated. For this purpose, an 8-story three-dimensional concrete structure is modeled and analyzed using OpenSees software. The modeled structure is first analyzed without dampers against the combined effects of an explosion with an earthquake. In this paper, the combined effect of explosions with 8 different earthquakes has been investigated separately. Then, in the next step, the placement of TADAS dampers and their specifications are designed in such a way that the performance level of the structure against this type of loading reaches the level of Immediate occupancy (IO) performance. Based on the results obtained from nonlinear static analysis of two structures without dampers and equipped with dampers, it was found that the use of dampers in this structure causes the capacity of the structure to increase by about two times. Also, based on nonlinear dynamic analysis of structures, it can be concluded that the use of this type of damper can reduce the drift and displacement of the structure by more than 60%. Also, using the correct arrangement of these dampers in irregular structures can reduce irregular effects.

Ammonium dinitramide (ADN) with a positive oxygen balance (25.8%) is a metal free- energetic compound, which is used in military explosives and smokeless or green solid propellants. Combustion products of solid propellants based on ADN are clean and smokeless and they do not release hydrogen chloride gas, which can be an excellent alternative compound as an oxidizer in the solid propellant formulation. Therefore, it is essential to study the thermal decomposition of ADN in the presence of catalysts. In this study, the catalytic effect of zinc oxide (ZnO) with different morphologies including decorated-nanoparticles, sub-microrods, microrods, and nanorods on ADN, was investigated. Samples were mixed by both physical and solvent methods. Finally, the catalytic effect of ZnO with different morphologies was investigated on the thermal decomposition of ADN by differential scanning calorimetry (DSC). Results showed that adding ZnO reduces the decomposition temperature of ADN. Also, ADN decomposes explosively in one step and in a shorter time in the presence of some morphologies of ZnO. In general, in the mechanical method, Microrods and Sub-Microrods samples have more desirable catalytic effects.

The heat treatment process was known as one of the most economical routes for development of the high strength steels. Low alloy AISI4140 steel was also famous for its widespread applications in the automotive and aerospace industries. Thus, a combination of heat treatment procedure and using this type of steel could be the economical and applicable process for various industries. As a result, in the current study, the effect of different heat treatment cycles on the yield and ultimate tensile strength and also elongation per cent of the low alloy AISI 4140 was conducted. All of the samples were heat-treated at 880 ˚C for 30 min to achieve Austenite and then quenched in a diesel fuel environment. To continue, by performing the heat treatment cycles at different conditions for each sample, the martensite, martensite-ferrite, and bainite phases were formed.By performing tensile and hardness tests on each of the samples, the mechanical properties, and with the penetration of 7.62 mm projectile of G3 gun, the ballistic properties of the samples were evaluated.