• Explosives and Blasting
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• v.41 no.3
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• pp.1-12
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• 2023

A basic assessment of techniques to mitigate the risk of blast shock waves from proximity explosions was conducted. Common existing techniques include using mitigant materials to form barriers around the explosive or in the direction of propagation of the shock wave. Various explosive energy dissipation mechanisms have been proposed, and research on blast shock wave mitigation utilizing impedance differences has drawn considerable interest. In this study, shear thickening fluid (STF) was applied as a blast mitigation material to evaluate the effectiveness of STF mitigation material on explosion shock wave mitigation through explosion experiments and numerical analysis. As a result, the effectiveness of the STF mitigant material in reducing the explosion shock pressure was verified.

• KIISE Transactions on Computing Practices
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• v.21 no.7
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• pp.443-451
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• 2015

This paper proposes a signal modelling method that can effectively detect the shock wave(SW) sound and muzzle blast(MB) sound from the gunshot of a small arm rifle. In order to localize a counter sniper in battlefield, an accurate detection of both shock wave sound and muzzle blast sound are the necessary keys in estimating the direction and the distance of the counter sniper. To verify the performance of the proposed algorithm, a real gunshot sound in a domestic military shooting range was recorded and analyzed. From the experimental results, the proposed signal modelling method was found to be superior to the comparative system more than 20% in a shock wave detection and 5% in a muzzle blast detection, respectively.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.897-919
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• 2015

In this study, the effects of ground shocks due to explosive loads on the dynamic response of historical masonry bridges are investigated by using the multi-point shock response spectrum method. With this purpose, different charge weights and distances from the charge center are considered for the analyses of a masonry bridge and depending on these parameters frequency-varying shock spectra are determined and applied to each support of the two-span masonry bridge. The net blast induced ground motion consists of air-induced and direct-induced ground motions. Acceleration time histories of blast induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectrums determined from the ground shock time histories are simulated using BlastGM software. The results obtained from uniform and multi-point response spectrum analyses cases show that significant differences take place between the uniform and multi-point blast-induced ground motions.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.1
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• pp.10-19
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• 2023

Blast Hardened Bulkhead (BHB) is an important measure that can increase the ship's survivability as well as protect the lives of the crew by mitigating the damage extent caused by an internal explosion in the ship. In particular, both the pressure and the shock impulse should be considered when designing the BHB against reflected shock waves having a high pressure with a short duration. This study proposes a design method for BHB that considers both the pressure and the shock impulse generated during the internal explosion. In addition, analysis and design concepts for accident loads such as explosion, fire, and collision of NORSOK and DNVGL, one of the international design guidelines for the curtain plate type blast hardened bulkhead type applied by the Korean Navy, are utilized. If this method is applied, it is expected that it can be used as a design concept for the pressure as well as the shock impulse of the explosion load of the curtain plate.

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

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

• Advances in materials Research
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• v.6 no.2
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• pp.155-168
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• 2017

The terrorist attacks and dangers by bomb blast have turned into an emerging issue throughout the world and the protection of the people and structures against terrorist acts depends on the prediction of the response of structures under blast and shock load. In this paper, behavior of aluminum and unidirectionally reinforced E-Glass Epoxy composite plates with and without focal circular holes subjected to shock loading has been identified. For isotropic and orthotropic plates (with and without holes) the classical normal mode approach has been utilized as a part of the processing of theoretical results. To obtain the accurate results, convergence of the results was considered and a number of modes were selected for plate with and without hole individually. Using a shock tube as a loading device, tests have been conducted to composite plates to verify the theoretical results. Moreover, peak dynamic strains, investigated by experiments are also compared with the theoretical values and deviation of the results are discussed accordingly. The strain-time histories are likewise indicated for a specific gauge area for aluminum and composite plates. Comparison of dynamic-amplification factors between the isotropic and the orthotropic plates with and without hole has been discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.409-414
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• 2011

A projectile that passes through a shock wave experiences drastic changes in the aerodynamic forces. These sudden changes in the forces are attributed to the wave structures produced by the projectile-shock wave interaction. A computational study using moving grid method is performed to analyze the effect of the projectile-shock wave interaction. Cylindrical and conical projectiles have been employed to study such interactions. This sort of unsteady interaction normally takes place in overtaking blast flow fields. It is found that the overall effect of overtaking a blast wave on the unsteady aerodynamic characteristics is hardly affected by the projectile configurations. However, it is noticed that the projectile configurations do affect the unsteady flow structures and hence the drag coefficient for the conical projectile shows considerable variation from that of the cylindrical projectile. The projectile aerodynamic characteristics, when it interacts with the secondary shock wave, are analyzed. It is also observed that the change in the characteristics of the secondary shock wave during the interaction is different for different projectile configurations.

• Structural Engineering and Mechanics
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• v.32 no.2
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• pp.235-249
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• 2009

The response of concrete structures subjected to shock and blast load involves a rapid transient phase, during which material breach may take place. Such an effect could play a crucial role in determining the residual state of the structure and the possible dispersion of the fragments. Modelling of the transient phase response poses various challenges due to the complexities arising from the dynamic behaviour of the materials and the numerical difficulties associated with the evolving material discontinuity and large deformations. Typical modelling approaches include the traditional finite element method in conjunction with an element removal scheme, various meshfree methods such as the SPH, and the mesoscale model. This paper is intended to provide an overview of several alternative approaches and discuss their respective applicability. Representative concrete material models for high pressure and high rate applications are also commented. Several recent application studies are introduced to illustrate the pros and cons of different modelling options.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.1
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• pp.38-44
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• 2015

In this paper, a finite element dynamic simulation study was performed to gain an insight about the blast wall test details for the offshore structures. The simulation was verified using qualitative and quantitative comparisons for different materials. Based on in-depth examination of blast simulation recordings, dynamic behaviors occurred in the blast wall against the explosion are determined. Subsequent simulation results present that the blast wall made of high energy absorbing high manganese steel performs much better in the shock absorption. In this paper, the existing finite element shock analysis using the LS-DYNA program is further extended to study the blast wave response of the corrugated blast wall made of the high manganese steel considering strain rate effects. The numerical results for various parameters are verified by comparing different material models with dynamic effects occurred in the blast wall from the explosive simulation.