• Title/Summary/Keyword: 폭발압력곡선

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A Suggestion of Simplified Load Formula for Blast Analysis (폭발해석을 위한 간략 폭발하중 제안식)

  • Jeon, Doo-Jin;Han, Sang-Eul
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.1
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    • pp.67-75
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    • 2016
  • In this paper, a pressure-time history curve of blast load and Conwep model are presented, and a simplified blast load formula is suggested. Generally, a blast load are applied as a pressure-time history curve, and it is calculated by blast load formula such as Conwep model. The Conwep model which is used in most of the blast analysis is quiet difficult to calculate because of its complex process. Therefore, a simplified formula is proposed to calculate blast load by simple rational expressions and to make a simplified pressure-time history curve. In this process, a curve fitting method was used to find the simple rational expressions. The calculation results of the simplified formula have an error of less than 1% in comparison with the Conwep model. And, blast analyses using finite elements method are accomplished with the Conwep model and simplified formula for verification.

Study on the Empirical Equations for Pressure Curve by Air Blast (폭발파에 의한 폭발압력곡선 경험식에 관한 연구)

  • Kwon, Sangki
    • Explosives and Blasting
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    • v.35 no.1
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    • pp.1-17
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    • 2017
  • The understanding of the pressure associated with air blast, which travels through air, and its effect on surface and underground structures is highly important. It is necessary to determine the pressure change with time and distance for a computer simulation of the explosion impact on a structure. From the previous studies, many empirical equations for estimating the parameters related to the pressure change. In this study, the empirical equations for predicting peak overpressure, duration of positive phase, impulse, minimum negative pressure, duration of negative pressure, arrival time, and decay constant were reviewed and analyzed. Also, the pressure changes predicted from the Kingery equation, which is the most commonly used, and from the other empirical equations were compared.

A Study on Physicochemical Characteristics of Hydrogen Gas Explosion (수소가스 폭발의 물리화학적 특성 연구)

  • Jo, Young-Do
    • Journal of the Korean Institute of Gas
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    • v.16 no.1
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    • pp.8-14
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    • 2012
  • Hydrogen is considered to be the most important future energy carrier in many applications reducing significantly greenhouse gas emissions, but the explosion safety issues associated with hydrogen applications need to be investigated and fully understood to be applicable as the carrier. The risk associated with a explosion depends on an understanding of the impacts of the explosion, particularly the pressure-time history during the explosion. This work provides the effects of explosion parameters, such as specific heat ratio of burned and unburned gas, equilibrium maximum explosion pressure, and burning velocity, on the pressure-time history with flame growth model. The pressure-time history is dominantly depending on the burning velocity and equilibrium maximum explosion pressure of hydrogen-air mixture. The pressure rise rate increase with the burning velocity and equilibrium maximum explosion pressure. The specific heat ratio of unburned gas has more effect on the final explosion pressure increase rate than initial explosion pressure increase rate. However, the specific heat ratio of burned gas has more influence on initial explosion pressure increase rate. The flame speeds are obtained by fitting the experimental data sets. The flame speeds for hydrogen in air based on our experimental data is very low, making a transition from deflagration to detonation in a confined space unlikely under these conditions.

Calculation of the TNT Equivalent Mass of the Possible Explosion of CO, CH4, and C2H4 (CO와 CH4, C2H4 혼합 가스 폭발에 대한 TNT 등가량 계산)

  • Kim, Minju;Kwon, Sangki
    • Explosives and Blasting
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    • v.38 no.1
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    • pp.1-13
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    • 2020
  • Gas explosion accidents are steadily being issued due to increased gas consumption in Korea and foreign countries. To analyze the effects of these gas explosions, a TNT equivalent method is used. In this study, the TNT equivalent was calculated in the event of an explosion due to the volume content in the air of CO, CH4 and C2H4, the typical flammable gases emitted by coal. Also, the peak overpressure and impulse variation with the distance from explosion point were compared and analyzed by gas using the calculated equivalent value of TNT. The upper limit of the TNT equivalent for the three mixed gases is up to five times larger than the other gases mixture. In addition, the peak overpressure and impulse, which are factors of the TNT characteristic curve, are also increasing as the number of gases increases.

충격 및 폭발하중에 의한 동적파괴 해석기법

  • 김경수
    • Computational Structural Engineering
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    • v.10 no.3
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    • pp.22-29
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    • 1997
  • 본 논문에서는 균열이 존재하는 구조부재에 충격이나 폭발하중이 가해진 경우 동적응력확대계수를 구하는 방법들은 논의하고 특히 코오스틱 실험법 및 수치적으로 코오스틱 곡선을 구하여 동적응력확대계수를 구하는 과정을 자세히 설명하였다. 폭발 및 충격에 의한 구조물의 파괴해석은 이와 같은 하중을 받는 압력용기, 빌딩, 초고속선, 해군 함정 등의 파괴강도설계 및 안전성 평가에 핵심기술로 대두되고 있으며 또한 우주항공산업, 고속전철, 암반역학 등의 여러 분야에서 중요한 의미를 갖는다. 따라서 앞으로도 균열진전 및 정지조건, 탄소성 동적파괴해석 및 재료의 충격거동 등에 대한 연구들이 계속되어져야 할 것으로 사료된다.

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Evaluation of Peak Overpressure and Impulse Induced by Explosion (폭발에 따른 최대과압 및 충격량 평가)

  • Yoon, Yong-Kyun
    • Explosives and Blasting
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    • v.34 no.4
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    • pp.28-34
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    • 2016
  • Empirical model, phenomenological model, and CFD model have been used to evaluate the blast effects produced by explosion of explosives, flammable gas and liquid or dust. TNT equivalence method which is one of empirical models has been widely used as it is simple. In this study, new peak overpressure-scaled distance and scaled impulse-scaled distance equations are induced through fitting data from the curves given by TNT equivalence method. If the TNT equivalent mass is calculated, it is possible to estimate the peak overpressure and impulse using the regression equations. Differences of peak overpressure with yield factor which is a component of TNT equivalence method are found to be great in near-by distances from explosion source where the increase in overpressure is very steep, but the differences are getting smaller as the distances increase.

The Effect of Negative Pressure Phase in Blast Load Profile on Blast Wall of Offshore Plant Topside (해양플랜트 Topside 방화벽에 폭발압의 부압구간이 미치는 영향)

  • Kang, Ki-Yeob;Choi, Kwang-Ho;Ryu, Yong-Hee;Choi, Jae-Woong;Lee, Jae-Myung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.4
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    • pp.281-288
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    • 2014
  • As a gas explosion is the most fatal accident in shipbuilding and offshore plant industries, all safety critical elements on the topside of offshore platforms should retain their integrity against blast pressure. Even though many efforts have been devoted to develop blast-resistant design methods in the offshore engineering field, there still remain several issues needed to be carefully investigated. From a procedure for calculation of explosion design pressure, impulse of a design pressure model having completely positive side only is determined by the absolute area of each obtained transient pressure response through the CFD analysis. The negative pressure phase in a general gas explosion, however, is often quite considerable unlike gaseous detonation or TNT explosion. The main objective of this study is to thoroughly examine the effect of the negative pressure phase on structural behavior. A blast wall for specific FPSO topside is selected to analyze structural response under the blast pressure. Because the blast wall is considered an essential structure for blast-resistant design. Pressure time history data were obtained by explosion simulations using FLACS, and the nonlinear transient finite element analyses were performed using LS-DYNA.

Evaluation on Blast Resistance Performance of Reinforced Concrete Wall Strengthened by FRP Sheet (FRP 시트로 보강된 철근콘크리트 벽체의 방호성능 평가)

  • Lee, Kun-Ho;Kim, Jae-Min;Kim, Jae Hyun;Lee, Sang-Hoon;Kim, Kang Su
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.5
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    • pp.151-160
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    • 2022
  • Owing to the recent increase in the frequency of explosion accidents, blast resistive design has garnered attention to reduce the damage of important structural elements. However, domestic research on the blast resistive structures is still insufficient, and domestic design guideline against blast loads are not documented yet. In this study, a numerical study on the RC blast resistive walls, where the test variable was the presence of FRP sheet, was performed using LS-DYNA program. Based on the numerical results, displacement-time hysteretic curve, pressure-impulse diagram, and fragility curve of the test specimens were derived. It was shown that the FRP sheet strengthening method is efficient to improve the blast resistive performance of the RC wall. Also, the strengthening effect of FRP sheet on the RC wall was stronger when the magnitude of the blast load was greater.

A Calibration Method of the CSC Model for Considering Material Properties of Ultra-high Performance Concrete (초고성능 강섬유 보강 콘크리트 물성 반영을 위한 소성 기반 콘크리트 CSC 모델 보정기법)

  • Gang-Kyu, Park;MinJoo, Lee;Sung-Wook, Kim;Hyun-Seop, Shin;Jae Heum, Moon
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.402-410
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    • 2022
  • The present study introduces a calibration method of the CSC model implemented in the LS-DYNA program for considering the material properties of ultra-high performance concrete(UHPC). Based on previous experimental studies, various parameters, which constitute three shear failure surfaces, pressure-volumetric strain curve, fracture energy, dynamic increase factor(DIF), and so on, are modified. Then, the proposed calibration method is verified by comparing the numerical result with the experimental data through the single element analysis. In addition, based on the established finite element models, the applicability of the calibrated CSC model is examined for UHPC structures subjected to impact and blast loadings.

Evaluation of the Aging Effects on the Performance of the Pyrotechnic Igniter (파이로 테크닉 점화기의 노화 성능 평가)

  • 장승교;류병태
    • Journal of the Korean Society of Propulsion Engineers
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    • v.1 no.2
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    • pp.91-102
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    • 1997
  • In order to evaluate the effects of aging on the ignition performance, pyrotechnic igniters were separated from twelve-year-old, fifteen-year-old, and sixteen-year-old live rocket motors. The characteristic values of the ignition material were measured, and the firing tests of the igniters were performed. The moisture content, the outer dimension, the crush strength, the thermal decomposition characteristics, and the heat of formation the B/$KNO_3$ ignition pellet were measured. The crush strength was increased and the heat of formation was reduced as aged, but no change was detected for other characteristic values. The burning test results of the igniter pellet in the closed bomb and the inert motor showed that the burning rate of the ignition pellet was increased by 10%, and the integration of pressure $P_t$ of the p-t curve was reduced by 15% for aged samples. It was inferred that the burning rate was increased as the crack was appeared in the pellet and $P_t$ could be proportionally decreased with the heat of explosion.

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