A DFT Treatment of Some Aluminized 1,3,3-Trinitroazetidine (TNAZ) Systems - A Deeper Look

1,3,3-Trinitroazetedine (TNAZ) is a powerful but insensitive energetic compound having C-NO2 and N-NO2 groups attached to a four-membered backbone. Aluminum powders are often added to explosives in order to have enhanced blast effect, etc. In the present study, aluminized TNAZ system is modeled for 1-3 Al atom(s) per TNAZ molecule within the restriction of density functional theory at the levels of UB3LYP/6-311++G(d,p) and UB3LYP/cc-PVDZ. Certain structural, physical and quantum chemical properties are obtained and discussed. The considered properties are found to be highly dependent on the multiplicity (thus the number of Al atoms present) of the composite systems considered. Also, calculated IR and UV-VIS spectra of the composites have been presented.

The new approach in evaluating the mechanism of the blast effect and organizing the blasting operations while tunneling

It is relevant for the organization of blasting operations with consideration to the mechanism of blast effect to justify new provisions due to the emergence of new explosives, means of initiating charges and instrumental measurement of parameters. In view of this, a new approach is needed for evaluating the mechanism of blast effect in the combined application of short-delay and delay-action blastings with a high level of organization and safety. Analyzing the results in the justification of the short-delayed blasting, obtained by many researchers in recent decades, its main advantages and some limitations in its evaluation have been identified. A clear justification for the combined application under seismic safety is provided. New results to explain the mechanism of the blast effect in the combined application of short-delay and delay-action blastings at tunneling facilities have been obtained. They help in the seismic action reduction under the conditions of close city development. Methodological approaches to organize blasting operations at complex facilities in Ukraine implemented during tunneling have been developed.

Blast Loading Response of Reinforced Concrete Panels Externally Reinforced with Steel Strips

Frequent terrorist activities, the use of vehicle bomb blasts and improvised explosive devices (IEDs) have brought forth the task of protection against blasts as a priority issue for engineers. Terrorists mostly target the areas where human and economic losses are significantly higher. It is really challenging to study the effects of blast loading on structures due to numerous variables. For instance, the type of detonation charge, explosive material, placement of charge and standoff distance, etc., are a few of the variables which make the system more complicated. Reinforced cement concrete (RCC) wall panels are commonly used for protecting important installations and buildings. In this research, the response of RCC wall panels has been investigated due to the blast effect caused by two TNT charge weights of 50 kg and 100 kg. These two charge weights have been selected after a detailed study of terrorist activities in the recent past. For this purpose, an existing arrangement at an important military installation, i.e., NESCOM Hospital Islamabad in Pakistan, has been selected. To reduce computational efforts, three RCC wall panels, placed side by side producing a continuous front along with a corresponding boundary and structural wall, have been considered. RCC wall panels are placed at a distance of 3 ft from the perimeter of the boundary wall and 23 ft from the structural wall. The displacement on the front face of RCC wall panels and the structural wall is measured at three levels of top, middle and bottom. ANSYS AUTODYN software has been used to simulate the model. Analysis has been carried out to identify and study the weakness of existing arrangements. Literature was reviewed for suggesting an appropriate strengthening technique for existing structures against blast loading. It was found that in addition to existing strengthening techniques, use of steel strips is amongst the most feasible technique for strengthening existing structures. It not only significantly enhanced the blast performance of structures, but it also significantly reduced z-direction displacements and pressures. The results show that the use of steel strips as the improvement technique for already placed RCC wall panels can be effective against a blast loading of up to 100 kg TNT.

Analysis of Structural Changes Created by the Blast Effect

Unfortunately, people can’t live in peace in this century: many wars and terrorist attacks have been witnessed even within the last year. In the case of such attacks, both the people and the civil infrastructure is in danger [1-3]. The modern age (infrastructure) provides electrical networks and communication networks for the citizens. Without electricity and/or communications (e.g. the internet), urban life is paralysed. Explosions create heat and shock waves and their effects can potentially damage the wall and cables of a building as changes in the material structure occur. In this article, the authors introduce a blast load effect testing method in an empirical way. The metal microstructure deformation level is measurable by changes in resistance, because resistance is a physical property which depends on the crystal structure of the metal.

Additively manufactured penetrating warheads

Penetrating warheads have to both defeat thick and high strength targets and have high blast effects. Lattice structures could help to enhance blast effect and reduce the weight of the penetrators. Additive manufacture provides a method to produce this concept. This paper details a programme to evaluate the perforation performance of such a penetrator. This study implemented an approach based on the integration of virtual and physical tests. A mesoscale numerical approach based on explicit high order finite element (HOFEM) was first developed to optimize the lattice pattern. The dynamic behaviour of this material was then determined using the Split Hopkinson Pressure Bar (SHPB) technique and this was then used to fit a constitutive model in Impetus Afea Solver®. The modelling of the concrete penetration of small scale warhead was based on the advanced meshless approach coupled with HOFEM. The models developed enabled the determination, simultaneously, of the homogenised behaviour of the lattice material and also the global behaviour of the penetrators during and after the penetration. Seven ballistic tests against concrete targets were performed at Thiot Ingenierie to investigate the penetration capabilities of the additively manufactured penetrating warhead concept and especially when using a lattice pattern.