Papers by Keyword: Blast Wave

Abstract: The pressure histories resulting from blast wave interactions with structures are highly influenced by the level of confinement. Fully confined blast events are more severe than their unconfined counterparts due to multiple wave reflections and residual quasi-static pressures, which result in prolonged shock-structure interactions and complex pressure profiles. Most experimental studies have primarily focused on spherical or hemispherical blast waves in free-field conditions, supporting simplified models like the CONWEP algorithm commonly integrated into Finite Element (FE) solvers for unconfined explosions. However, this approach is unsuitable for more complicated scenarios, such as explosions in confined scenarios. The current study presents an approach that integrates CFD with a FE framework. This work focuses on extending the capabilities of the FE solver Abaqus/Explicit to handle these complex load histories, which are beyond the scope of its default built-in configurations. User-defined subroutines are developed to enable an Uncoupled Lagrangian-Eulerian (UEL) framework. CFD simulations are performed independently to calculate pressure histories, then they are subsequently mapped onto structural FE models as input loads. The results demonstrate that the proposed framework extends the range of scenarios that can be analysed for blast wave propagation and its effects on structures. By employing this uncoupled approach, diverse structural simulations can be performed using a single FE model. This study provides a numerical tool for simulating confined explosions, with applications in industrial safety and structural design facilitating improved engineering designs for mitigating blast effects.

Abstract: The mechanism of damage on the structure of an explosion pit which belongs to the Institute of Pulsed Power Science, Kumamoto University is investigated. Investigated is the mechanism of damage on the structure of an explosion pit which belongs to the Institute of Pulsed Power Science, Kumamoto University. Here, three-dimensional model with square opening (door) is used to simulate by numerical simulation. The numerical result with the actual egg-type model implies that firstly the cracks occurred at the corners of the door and grew larger. In addition, the numerically simulated results with a spherical form model are also demonstrated to study on optimizing the design of an explosion pit.

Abstract: This paper investigates explosions in a straight square tube in order to understand the mitigation effect of water on blast waves that emerge outside. Numerical simulations are used to assess the effect of water that is put inside the tube. The water reduces the peak overpressure outside, which agrees well with the experimental data. The increases in the kinetic and internal energies of the water are estimated, and the internal energy transfer at the air/water interface is shown to be an important factor in mitigating the blast wave in the present numerical method.

Abstract: The presented paper is focused on the practical aspects of retrofit technique used for blast protection of buildings. It presents the summary of various retrofit techniques.

Abstract: The aim of the paper is to provide an expert opinion on the issue of charge size estimation of used explosion weight according to the caused damages on the sourronings buildings. The research is focused on the analytical approach of setting the weight of explosives used in explosive improvised devices, using a current state-of-art of blast pressure setting. The vice versa methodology is to estimate the weight of used explosive from maximal pressure of blast wave.

Abstract: This work considers the questions of low-alloy tool steel cementation by laser treatment. The model of surface layer carbon saturation from the laser-induced plasma is shown. It is described that the diffusion process in the laser treatment can not be explained only by the influence of temperature gradient. The results of the experimental work confirmed the increasing intensity of the process surface layer saturation with carbon. The work describes the influence of the laser emission power on surface layer microstructure formation. The test results of the hardened samples showed an approximately two-time increase in durability.

Abstract: With the increase in acts of terrorism, the effects of the explosion on structures has become highly topical. The aim of the paper is an analysis of various approaches to determine the response of blast loaded reinforced concrete pillar. Homemade ANFO (Ammonium nitrate + fuel oil) explosive will be a reference explosive. Such type of explosives is the most used one in terroristic attacks. The paper will be focused on the analysis of the blast wave, based on the experimental tests, and dynamic analysis of a structure under such load.

Abstract: An investigation has been done to numerically simulate the radiation losses which occur due to laser energy deposition in a domain. Although the fluid dynamic effects due to laser energy deposition has been studied by a number of researchers independently but the effect of radiation has either been neglected or has not been highlighted effectively. When laser energy is deposited in a domain, very high temperatures are reached. At such high temperature, the diatomic air species may become highly dissociated and emission from the resulting two mono atomic species N and O cannot be neglected and is the major source of radiation loss. An Open Source CFD software Open Foam has been used to study the above effects. P1 radiation model along with radiation Line by Line method has been used to calculate the radiation losses. Radiation losses obtained are 20 times higher as compared to the only one past reported data but still are negligible as compared to the deposited energy. Hence our study validates the assumption of neglecting radiation losses, which was assumed earlier in all previous studies without any proper validation, using the most accurate LBL method.

Abstract: In order to analyze the explosion characteristics on the free field performance of thermobaric explosive, parameters of blast waves produced by the investigated charges in an open space were measured by the use of piezoelectric sensors and the results were compared to traditional TNT. Moreover, a numerical simulation of TBE explosion in free field was performed within the frame of AUTODYN. Comparison with TNT reveals that the values of peak pressure and impulse of TBE are higher than that of TNT due to the secondary reaction of Al and detonation products. It is found that the simulation results of TBE detonation blast wave parameters coincided very well with the experiment data. This demonstrates that the simulation method used is an effective way to depict the spreading of detonation waves in free field for TBE.

Abstract: The threat of terrorism has led to increased awareness about protecting properties from damage in terrorist attacks. With the rapid growth of the computer industry and progress in the field of finite-element analysis, evaluations of conventional weapons focus more on simulations than on experiments. There are many approaches to simulate blast and impact. These include Eulerian, Lagrangian, multi-material arbitrary Lagrangian-Eulerian (MM-ALE), and the meshless approach of smooth particle hydrodynamics (SPH) methods. Each method has distinct advantages. In this study, finite-element analysis was applied to simulate a 1 kg trinitrotoluene (TNT) blast in front of a 20-mm-thick steel plate. Three different approaches were simulated: Eulerian, MM-ALE, and SPH. Each method gave different results for the von Mises stress distribution, peak pressure, and displacement of the steel plate. A comparison of the three results implies that using one of these three approaches may generate a significant blast simulation.