Simplified Algorithm Model for Explosion Shockwave Load in the Cabin

In order to obtain the shockwave load simplified algorithm model for the semiarmored projectile internal explosion in the cabin, this research made use of AUTODYN to provide a numerical modeling method for explosion in the cabin and verified the accuracy of the method via the experiment. Internal explosion simulation calculation was conducted on the operating condition numerical model with different cabin structural dimensions and different explosive loads. The cabin internal explosion space was divided into the noncorner central area, near-wall area, two-sided corner area, and three-sided corner area. Through regression of the abovementioned calculation results, an engineering model to calculate the shockwave load was obtained. It is hoped that the model can offer some references to the antiexplosion design for the ship cabin and for damage assessment of the internal explosion.

Anti-explosion Capability and Impact Response of an Innovative Multi-layered Composite Explosion Containment Vessel

Owing to its advantages of high strength and low density, composite explosion containment vessel (CECV) can limit the scope of internal explosion shock wave, thereby reducing the damage to the surrounding environment and protecting human life and property. However, due to the complexity of the explosion process and related structure, the mechanism by which shock wave is induced on the inner lining of the explosion containment vessel (ECV) and the influence of the structural parameters of ECV on the reflection overpressure of the inner wall are not understood clearly. In this study, the characteristic of the internal explosion pressure load of a single-layer ECV is examined through experimental tests and simulations, and a three-dimensional mesoscopic model is established and verified. Furthermore, to solve the problem of the restricted explosion resistance of the single-layer ECV, a new steel plate-aluminum honeycomb-fiber cloth sandwich structure with sliding lining is proposed to design a multi-layer CECV. For the arrangement of fiber filaments, uniform distribution, random distribution, and honeycomb distribution algorithms are established based on Python language. Finally, a finite element model of the CECV is established, and a series of explosion simulations are conducted. The results indicate that the laying angle of the fibre cloth has no effect on the peak overpressure inside the ECV, and the ECV exhibits the best protective property when the laying angle of the fibre cloth is 0°/ 45°/ 90°/ 45°/ 0°. It is also observed that the steel plate-aluminium honeycomb-fibre cloth sandwich structure prolongs the action time of the explosion shock wave and greatly reduces the peak pressure in the CECV. Remarkably, for the weakest position of the tank, the strain for the multi-layer CECV under 3000 g TNT is even less than that for the single-layer ECV under 150 g TNT.

Model load in case of an internal explosion

Introduction. Presently, there are no model loads that describe the burst effect of an internal explosion. The goal of the article is to design a model load that characterizes an internal explosion with regard for the effect of inertial safety structures. The author provides relevant examples.Methods. The experiment and the numerical modeling identify the characteristics of an internal explosion, primarily, its destructive effect. First of all, these characteristics include the pressure value and rate in the process of the first peak formation. A drop follows the first peak. Another rise to the second peak is followed by the final pressure drop. The rise to the first peak is described by a cubic parabola. The constant value of pressure is equal to the highest value of the two peaks. It replaces the drop and rise between the peaks. The linear dependence describes the area of the final pressure drop, so that the deformation is completed at the end point. The time of the pressure rise is determined by breakup, and it takes account of the characteristics of safety structures. The time of the second peak is the time when the flame area is maximal.Results and discussion. The deformation that may occur before the first peak represents a solution to the equation, describing the beam motion. This equation is provided in the article. The deformation between the peaks is determined by the balance of energy. The deformation, that occurs when the pressure drops, is identified by the solution to the motion equation. The solution is subject to the deformation completion condition.Conclusions. The results show that the time between the peaks is important when the pressure is close to maximal. The analysis identifies the conditions under which deformation remains elastic. These results can be contributed to the assessment of the bearing capacity of buildings that accommodate explosive production facilities. This approach ensures conservative results.

Study on Reduction Effect of Vibration Propagation due to Internal Explosion Using Composite Materials

With the increasing installation cases of underground explosive facilities (e.g., ammunition magazines, hydrogen tanks, etc.) in urban areas in recent years, the risk of internal explosions is also increasing. However, few studies on the measures for reducing damage by the ground vibration have been conducted except for maintaining safety distance. In this study, a method for attenuating the vibration propagated outward by installing a blast-proof panel was numerically and experimentally investigated. Two cubical reinforced concrete structures were manufactured according to the concrete strength and a blast-proof panel was installed on only one side of the structure. Then, acceleration sensors were installed on the external surface to evaluate the propagation of vibration outward depending on the installation of a blast-proof panel. Before a field experiment, a preliminary numerical simulation was performed. The results showed that the acceleration propagated outward could be effectively reduced by installing a blast-proof panel. Even though the performance of a blast-proof panel on vibration reduction was also investigated in the field experiment, significantly larger absolute accelerations were estimated due to the different experimental conditions. Finally, the vibration reduction effect of the blast-proof panel was numerically evaluated according to its thickness and the internal explosion load. A blast-proof panel more effectively reduced the acceleration propagated outward as its thickness increased and the explosion load decreased.

Pressure Load Characteristics of Explosions in an Adjacent Chamber

To learn more about dynamite explosions in confined spaces, we focused on the chamber adjacent to the main chamber, the main chamber being the location of the explosion. We investigated the characteristics of two damaging pressure loads: first reflected shock wave and quasistatic pressure. In this work, we analyzed the characteristics of the first reflected shock wave and the quasistatic pressure formed by the explosion of the chamber charge. Simulated chamber explosion experiments were carried out, where high-frequency piezoelectric sensors were used to measure the first reflected shock wave, and low-frequency piezo-resistive sensors were used to measure the quasistatic pressure. Valid and reasonable experimental data were obtained, and the experimental values of the pressure load were compared with those calculated from the classical model. The results showed that when the main chamber was partially damaged by the explosion load, the adjacent chambers were not subjected to the shock wave load, and the quasistatic pressure load was less than that in the main chamber. The presence of adjacent chambers did not affect the shock wave load in the main chamber. Using the mass of the explosive and the blast distance as input parameters, the internal explosion shock wave load parameters, including those in adjacent chambers, can be calculated. The presence of the adjacent chamber did not affect the theoretically calculated quasistatic overpressure peak in the main chamber. Using the mass of the explosive and the spatial volume of the chamber as input parameters, the quasistatic pressure load parameters of the internal explosion can be calculated, including those in the adjacent chambers.

Assessment of structural bearing capacity in case of internal explosion

The work has developed a method for determining the deformation of bent rod structures during an internal explosion. When consideration of a quasi-stationary explosion, a model load is proposed, taking into account the pressure rise section to the maximum value at the beginning of the explosion, then a stationary section and then a decline. The pressure in the stationary area is equal to more of the two peaks. With a sufficiently long stationary section, the maximum deformation is realized here, and is also determined from the energy balance. In the case of a short section of stationary pressure, maximum deformation develops towards the end of the explosion after a pressure drop. The solutions are suitable for describing deformation of beams with different fastening at the ends and are limited to the case when the maximum value of the load does not exceed the resistance of the structure. The results of the work can be used in assessing the load capacity of elements of explosive industries, residential premises, taking into account the action of protective structures.

Internal explosion. Pressure peaks

Internal emergency gas explosions occur at threatening intervals and cause significant destruction. The level of destruction indicates the imperfection of protection methods. Documents regulating the use of safety structures for the protection of buildings during an internal explosion are limited by the assignment of the area of openings covered by safety structures, without taking into account the properties of these structures, attachment methods and the rate of pressure increase during an explosion. The purpose of the work is to take into account as much as possible the influence of the properties of the protective structures, their attachment and the nature of the explosion on the dynamics of the explosion pressure change. The second goal is to obtain a methodology for converting the results of experimental results obtained on small volumes to determine the parameters of an explosion in conditions of large volume. The goals are achieved by the theory of dimensions and similarity using numerical modeling. The work revealed dimensionless complexes describing pressure dynamics both during opening of openings and at the moment of maximum power of energy release during explosion. Possibility of experimental scale modeling of processes of opening of safety structures is shown. In particular, it is shown that during an explosion in premises of a small volume (residential), the pressure during opening is more often critical.