TNT equivalent

Abstract: This study is part of an effort to assess the mechanical effects of an accidental explosion of a gaseous mixture cloud (hydrogen–air in this paper) in an unvented structure and deals with the detonation phenomenon. The aim of this paper is to present and estimate the adequacy of different approaches addressed to dynamic loading approximations. For this purpose, the research is based upon an experimental study at laboratory scale which constitutes the first of the approaches analysed. The experimentation is conducted with respect to the Hopkinson scaling law which allows one to estimate pressure in large-scale geometry. Thereafter, the capabilities of the Autodyn code to predict the pressure loads in confined surroundings are determined. The use of the computational code is a two-step process. Firstly, the incident pressure field is determined by the detonation of the TNT equivalent mass of the gaseous mixture; then the pressure field is introduced in the calculation domain and the interaction with the structure is observed. In addition, the simplified method proposed by Baker is also verified. This paper is an attempt to answer the following question: what is the best safety assessment strategy for the structures subjected to internal blast wave loading? Pressure on the faces of the structure has a complicated evolution, but is thoroughly described in the Autodyn code approach.

Abstract: A number of models have been proposed to calculate overpressure and impulse from accidental industrial explosions. When the blast is produced by explosives, pyrotechnics or unstable substances, the TNT equivalent model is widely used. From the curves given by this model, data are fitted to obtain equations showing the relationship between overpressure, impulse and distance. These equations, referred to here as characteristic curves, can be fitted by means of power equations, which depend on the TNT equivalent mass. Characteristic curves allow determination of overpressure and impulse at each distance.

Abstract: The performance of energy infrastructures under extreme loading conditions, especially for blast and impact conditions, is of great importance despite the low probability for such events to occur. Due to catastrophic consequences of structural failure, it is crucial to improve the resistance of energy infrastructures against the impact of blasts. A TNT equivalent method is used to simulate a petroleum gas vapor cloud explosion when analyzing the dynamic responses of a spherical tank under external blast loads. The pressure distribution on the surface of a 1000 m 3 spherical storage tank is investigated. The dynamic responses of the tank, such as the distribution of effective stress, structural displacement, failure mode and energy distribution under the blast loads are studied and the simulation results reveal that the reflected pressure on the spherical tank decreases gradually from the equator to the poles of the sphere. However, the effects of the shock wave reflection are not so evident on the pillars. The structural damage of the tank subjected to blast loads included partial pillar failure from bending deformation and significant stress concentration, which can be observed in the joint between the pillar and the bottom of the spherical shell. The main reason for the remarkable deformation and structural damage is because of the initial internal energy that the tank obtained from the blast shock wave. The liquid in the tank absorbs the energy of impact loads and reduces the response at the initial stage of damage after the impact of the blast.

Abstract: An underwater explosion test is used to determine the detonation properties of metallized explosives containing aluminum and boron powders. An oxygen bomb calorimeter (PARR 6200 calorimeter, Parr Instrument Company, USA) is used to obtain the heat of combustion of the metal mixtures. As the content of boron powders is increased, the heat of combustion of the metal mixtures increases, and the combustion efficiency of boron decreases. The highest value of the combustion heat is 38.2181 MJ/kg, with the boron content of 40%. All metallized explosive compositions (RDX/Al/B/AP) have higher detonation energy (including higher shock wave energy and bubble energy) in water than the TNT charge. The highest total useful energy is 6.821 MJ/kg, with the boron content of 10%. It is 3.4% higher than the total energy of the RDX/Al/AP composition, and it is 2.1 times higher than the TNT equivalent.