• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.145-161
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• 2021

Dynamic compaction of Aluminum powder using gas detonation forming technique was investigated. The experiments were carried out on four different conditions of total pre-detonation pressure. The effects of the initial powder mass and grain particle size on the green density and strength of compacted specimens were investigated. The relationships between the mentioned powder design parameters and the final features of specimens were characterized using Response Surface Methodology (RSM). Artificial Neural Network (ANN) models using the Group Method of Data Handling (GMDH) algorithm were also developed to predict the green density and green strength of compacted specimens. Furthermore, the desirability function was employed for multi-objective optimization purposes. The obtained optimal solutions were verified with three new experiments and ANN models. The obtained experimental results corresponding to the best optimal setting with the desirability of 1 are 2714 kg·m-3 and 21.5 MPa for the green density and green strength, respectively, which are very close to the predicted values.

• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.9-15
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• 2016

The theoretical investigation has been performed to predict detonation velocity, detonation pressure, and thermodynamic stability of HMX/LLM-116 cocrystal. All possible geometries of HMX, LLM-116, and cocrystal have been optimized at the B3LYP/cc-pVTZ level of theory. The binding energy for the trigger bond and cluster has been calculated to predict the thermodynamic stability. The MP2 binding energies were obtained using single point energy calculation at the B3LYP optimized geometries, and the density has been calculated from monte carlo integration. The detonation velocity and detonation pressure have been calculated using Kamlet-Jacobs equation, while enthalpy has been predicted at the CBS-Q level of theory.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1094-1103
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• 2008

A fuel specific detonation wave in a pipe propagates with a predictable wave velocity. This internal detonation wave speed determines the level of flexural wave excitation of pipes and the possibility of resonant response leading to a large displacement. In this paper, we present particular solutions of displacements and the resonance conditions for internally loaded pipe structures. These analytical results are compared to numerical simulations obtained using a hydrocode(multi-material blast wave analysis tool). We expect to identify potential explosion hazards in the general power industries.

• Explosives and Blasting
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• v.33 no.3
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• pp.1-13
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• 2015

Accidents related to gas explosion are frequently happened in foreign countries and in Korea. For the evaluation and the analysis of gas explosions, TNT equivalent methods are used. In this study, the influence of the selection of chemical equation in TNT explosion and the selection of enthalpy of the products on the explosion energy, detonation pressure, velocity of detonation, and temperature was calculated. Depending on the chemical equations, the maximum detonation pressure can be 2 times higher than the minimum. As an example for applying TNT equivalent method, an explosion of methane gas in a confined volume was assumed. With the TNT equivalent, it was possible to predict the variation of peak overpressure and impulse with the distance from the explosion location.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1913-1918
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• 2012

The nitramine explosives with $-NH_2$ and -F groups were optimized to obtain their molecular geometries and electronic structures at DFT-B3LYP/6-31+G(d) level. The theoretical molecular density (${\rho}$), heat of formation (HOF), detonation velocity ($D$) and detonation pressure ($P$), estimated using Kamlet-Jacobs equations, showed that the detonation properties of these compounds were excellent. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were respectively related with the temperature. The simulation results reveal that 1,3,5,7-tetranitro-1,3,5,7-tetrazocan-2-amine (molecule B1) performs similarly to the famous explosive HMX, and 2-fluoro-1,3,5-trinitro-1,3,5-triazinane (molecule C1) and 2-fluoro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (molecule D1) outperform HMX. According to the quantitative standard of energetics and stability as an HEDC (high energy density compound), molecules C1 and D1 essentially satisfy this requirement. These results provide basic information for molecular design of novel high energetic density compounds.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.617-621
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• 2017

The performance characteristics of aluminized high explosive are considered by varying the aluminum(Al) concentration in a two-phase model. Since the time scales of the characteristic combustion process of high explosives and Al particles differ, the process of energy release behind the leading detonation wave front occurs over an extended period of time. Two cardinal observations are reported: a decrease in detonation velocity with an increase in Al concentration and a double front detonation (DFD) feature when anaerobic Al reaction occurs behind the front. In the current study, a series of confined rate sticks are considered for characterizing the performance of aluminized HMX with a maximum Al concentration of 50%. The simulated results are compared with the experimental data for 5%-25% concentrations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.440-444
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• 2017

Two-dimensional hydrodynamic analysis was performed to analyze the attenuating characteristics of shock waves generated by the detonation of the bulkhead initiator. Through the interlocking analysis between HNS and HMX stacking initiator and STS bulkhead, we have precisely simulated detonation growth and pressure wave attenuation phenomena. The free surface velocity at the surface of the bulkhead was measured for quantitative comparison with the test data by VISAR. As a result, it was confirmed that the pressure attenuating pattern of the shock wave exponentially decreased according to the bulkhead thickness. The observed inflection point at the particle velocity measured over time is due to the subsequent propagation of the shock wave due to the rapid spallation of the interface between the detonator and the bulkhead.

• Journal of the Korean Chemical Society
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• v.66 no.3
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• pp.185-193
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• 2022

The theoretical investigation has been performed to predict thermodynamic stability, density, detonation velocity, and detonation pressure of energetic salts produced by pairing of nitrogen-rich anions (tetrazine, oxadiazole etc.) and cations (NH₃OH⁺, NH₂NH₃⁺, CH₉N₆⁺, C₂H₆N₅⁺). All possible geometries and the binding energy for the trigger bond of energetic salts have been optimized at the B3LYP/cc-pVDZ level of theory. The detonation velocity and detonation pressure have been calculated using Kamlet-Jacobs equation, while enthalpy has been predicted at the G2MP2 level of theory. The predicted results reveal that the energetic salts including small sized NH₃OH⁺(1) and NH₂NH₃⁺(2) cations increase detonation property. And also the energetic salts including more amino group (-NH₂) such as CH₉N₆⁺(3) cation increase thermodynamic stability. These results provide basic information for the development the high energy density materials (HEDMs).

• Explosives and Blasting
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• v.28 no.2
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• pp.69-75
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• 2010

Excavations by blasting in urban area have caused lots of complaints. Hence, special attentions need to be paid to controlling the ground vibrations in designing blasting for those areas. In this study, among the various parameters that can affect the propagation characteristics of ground vibrations, the effect of the priming location of explosive on the ground vibration level was studied for two types of emulsion explosives that had different detonation velocities. Three priming locations of top, middle, and bottom were considered in a charged hole. In the experiment on the effect of detonation velocity, the ground vibration caused by the explosive with a lower detonation velocity showed larger attenuation in the amplitude. The priming locations also affected the ground vibrations levels. The ground vibration level produced from middle priming was found to be larger than the other priming methods under the same blast conditions, but the attenuation of amplitude was also larger in this case. In contrast, the ground vibration level from bottom priming was not larger than the middle priming, but the attenuation was smaller so that the ground vibration was detected at a longer distance.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.706-712
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• 2014

Explosives are reactive material that contain a great amount of high potential energy. They produce detonation if released suddenly, accompanied by the production of strong light, high heat, great noise and high pressure. Damage at surrounding detonation point is affected by high pressure and blast wave for explosives detonation. Consequently, analysis of pressure and blast wave is very important. This study focuses on the analysis of maximum overpressure and blast wave of explosives for safety assurance. First of all, four cases of the amount of HMX were selected. Secondly, maximum pressure and blast wave were calculated through detonation simulation along with a set of TNT and HMX quantities. The peripheral effect of detonation point was analyzed by calculating overpressure and absolute velocity and considering detonation occurred in the center of geometry by HMX. Also, maximum overpressure and blast wave of HMX were compared to equivalent amount of TNT, which was taken as a base case and verified through theoretical HMX graph. This study contributes to the base case for overpressure and blast wave of complex gunpowder containing HMX.