• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.4
• /
• pp.462-468
• /
• 2016

In this paper, we present the results of the numerical analysis employing CONWEP, LS-DYNA FSI(Fluid Structure Interaction), AUTODYN FSI, LS-DYNA ALE(Arbitrary Lagrange Eulerian) and combination of CONWEP and LS-DYNA ALE for blast door fracture and wave propagation through the tunnel by the external explosion. We compared the numerical analysis results with the subscale test data and selected combination of CONWEP and LS-DYNA ALE method as adequate data generation method for the FRM(Fast Running Model) software development. It is expected to save much time and costs by using the numerical simulation data for the various test conditions.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.8
• /
• pp.1989-1998
• /
• 1995

Characteristics of the flame propagation for normal and abnormal combustion in hydrogen premixture in a cylindrical constant-volume combustion chamber are studied numerically. A detailed hydrogen oxidation kinetic mechanism, mixture transport properties and a model describing spark ignition process are used. The calculated pressure-time history of the stable deflagration wave propagation agrees well with the experiment. The ignition of the premixture in the unburned gas, initiated by the hot spot, causes a transition from deflagration to detonation under some initial temperature and pressure. Under the initial conditions with high temperature and pressure, excessive ignition energy initiates a strong blast wave and a detonation wave that follows. The chemical reaction in the detonation wave is much more vigorous than that in the deflagration wave and the peak pressure in the detonation wave is much higher than the equilibrium value.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.23 no.1
• /
• pp.43-51
• /
• 2020

In this study, numerical analysis was carried out on a complex pressure field of blast waves caused by the detonation of high explosives in various environments. The generated blast waves propagated in the air, upon the sudden release of high energy induced by the explosion. Reflected waves were created when the pressure waves encountered certain obstacles such as the ground or the walls of structures. The propagation of the blast waves and its interaction with the reflected waves were simulated. An adaptive mesh refinement was applied to improve the efficiency of distribution of computer resource, for the computational calculation of the blast wave propagation in a wide open space. In addition, the integration of the calculation domains for the explosive and air were considered when the maximum density of the explosive region was below critical value. The results were verified by comparison with the pressure time history from blast wave experiments performed under two topographical conditions.

• Structural Engineering and Mechanics
• /
• v.48 no.4
• /
• pp.569-585
• /
• 2013

The use of the rigid polyurethane foam (RPF) to strengthen sandwich structures against blast terror has great interests from engineering experts in structural retrofitting. The aim of this study is to use the RPF to strengthen sandwich steel structure under blast load. The sandwich steel structure is assembled to study the RPF as structural retrofitting. The filed blast test is conducted. The finite element analysis (FEA) is also used to model the sandwich steel structure under shock wave. The sandwich steel structure performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the field blast test and the numerical model. The RPF improves the sandwich steel structure performance under the blast wave propagation.

• Explosives and Blasting
• /
• v.36 no.3
• /
• pp.1-9
• /
• 2018

This study was conducted to evaluate the influences of the angle of artificial joints, the distance between the artificial joints and the blast hole, and the number of artificial joints on the pressure wave propagation, crack propagation, and blast wave velocity. The evaluation was conducted numerically by use of the Euler-Lagrange solver supported by the AUTODYN, which is a dynamic FEM program. As a result, it was found that the blast wave velocity was decreased most rapidly as either the distance between the artificial joint and the blast hole was decreased or the angle of the artificial joint was increased. In contrast to the case of no artificial joint, the amount of attenuation of the blast wave velocity was considerably large when an artificial joint was present. However, the effect of the number of artificial joint on the attenuation of the blast wave velocity was negligible under the given condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.45-52
• /
• 2008

In order to investigate the initiation and propagation processes of a spherical detonation wave induced by direct initiation, numerical simulations were carried out using two-dimensional compressible Euler equations with an axisymmetric assumption and a one-step reaction model based on Arrhenius kinetics with various levels of ignition energy. By varying the amount of ignition energy, three typical initiation behaviors, which were subcritical, supercritical and critical regimes, were observed. Then, the ignition energy of more than $137.5{\times}10^6$ in non-dimensional value was required for initiating a spherical detonation wave, and the minimum ignition energy(i.e., critical energy) was less than that of the one-dimensional simulation reported by a previous numerical work. When the ignition energy was less than the critical energy, the blast wave generated from an ignition source continued to attenuate due to the separation of the blast wave and a reaction front. Therefore, detonation was not initiated in the subcrtical regime. When the ignition energy was more than the minimum initiation energy, the blast wave developed into a multiheaded detonation wave propagating spherically at CJ velocity, and then a cellular pattern radiated regularly out from the ignition center in the supercritical regime. The influence on ignition energy was observed in the cell width near the ignition center, but the cell width on the fully developed detonation remained constant during the expanding of detonation wave due to the consecutive formation of new triple points, regardless of ignition energy. When the ignition energy was equal to the critical energy, the decoupling of the blast wave and a reaction front appeared, as occurred in the subcrtical regime. After that, the detonation bubble induced by the local explosion behind the blast wave expanded and developed into the multiheaded detonation wave in the critical regime. Although few triple points were observed in the vicinity of the ignition core, the regularly located cellular pattern was generated after the onset of the multiheaded detonation. Then, the average cell width on the fully developed detonation was almost to that in the supercritical regime. These numerical results qualitatively agreed with previous experimental works regarding the initiation and propagation processes.

• Computers and Concrete
• /
• v.14 no.6
• /
• pp.767-783
• /
• 2014

The use of composite materials to strengthen reinforced concrete (RC) structures against blast terror has great interests from engineering experts in structural retrofitting. The composite materials used in this study are rigid polyurethane foam (RPF) and aluminum foam (ALF). The aim of this study is to use the RPF and the ALF to strengthen the RC panels under blast load. The RC panel is considered to study the RPF and the ALF as structural retrofitting. Field blast test is conducted. The finite element analysis (FEA) is also used to model the RC panel under shock wave. The RC panel performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the field blast test and the proposed numerical model. The composite materials improve the RC panel performance under the blast wave propagation.

• 한국전산유체공학회:학술대회논문집
• /
• 2006.05a
• /
• pp.292-295
• /
• 2006

The terrorist attack of September $11^{th}$ 2001 has enforced a new examination of the response of modern steel structures, such as those found in large warehouses, auditoriums and airport terminals, to terrorist bomb attack. The effort described in this paper assesses the potential damage to such a newly designed structure form a medium-size car bomb. The structure is mostly composed of a lightweight complex beam structure with large windows and skylights piercing through a corrugated roof. The structural response to the terrorist attack requires the modelling of various physics phenomena including bomb detonation, blast wave propagation, reflections, and refractions and resulting blast impact on the structure. Hence, a fluid/structure coupled methodology is used to perform the assessment.

• Structural Engineering and Mechanics
• /
• v.53 no.3
• /
• pp.589-605
• /
• 2015

The use of the rigid polyurethane foam (RPF) to strengthen buried structures against blast terror has great interests from engineering experts in structural retrofitting. The aim of this study is to use the RPF to strengthen the buried structures under blast load. The buried structure is considered to study the RPF as structural retrofitting. The Guowei model (Guowei et al. 2010) is considered as a case study. The finite element analysis (FEA) is also used to model the buried structure under shock wave. The buried structure performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the Guowei model and the proposed numerical model. The RPF improves the buried structure performance under the blast wave propagation.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.10
• /
• pp.1053-1061
• /
• 2009

The goal of this paper is to investigate the generation characteristics of the main impulsive noise sources generated by the supersonic flow discharging from a muzzle. For this, this paper investigates two fundamental mechanisms to sound generation in shocked flows: shock motion and shock deformation. Shock motion is modeled numerically by examining the interaction of a sound wave with a shock. The numerical approach is validated by comparison with results obtained by linear theory for a small disturbance case. Shock deformations are modeled numerically by examining the interaction of a vortex ring with a blast wave. A numerical approach of a dispersion-relation-preserving(DRP) scheme is used to investigate the sound generation and propagation by their interactions in near-field.