• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.1
• /
• pp.67-75
• /
• 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.

• Journal of the Society of Naval Architects of Korea
• /
• v.61 no.1
• /
• pp.44-50
• /
• 2024

In order to reasonably predict damage extents of naval ships under in-compartment explosion (INCEX) loads, two conditions should be fulfilled in terms of accurate INCEX load generation and fracture estimation. This paper seeks to predict damage extents of various naval ships by applying the CONWEP model to generate INCEX loads, combined with the Hosford-Coulomb (HC) and localized necking (LN) fracture model. This study selected a naval ship with a 2,000-ton displacement, using associated specifications collected from references. The CONWEP model that is embedded in a commercial finite element analysis software ABAQUS/Explicit was used for INCEX load generation. The combined HC-LN model was used to simulate fracture initiation and propagation. The permanent failures with some structural fractures occurred where at the locations closest to the explosion source points in case of the near field explosions, while, some significant fractures were observed in way of the interfaces between bulkheads and curtain plates under far field explosion. A large thickness difference would lead to those interface failures. It is expected that the findings of this study enhances the vulnerability design of naval ships, enabling more accurate predictions of damage extents under INCEX loads.

• Explosives and Blasting
• /
• v.28 no.1
• /
• pp.55-62
• /
• 2010

Explosive welding was planed in a closed drift of a mine for its reuse. In this study, we analyzed the stabilization of roof and pillar which were expected to be affected by overpressure experienced during the continual explosive welding. Three equations, normal equation, CONWEP and DDESB, were used for the estimation of overpressure. The investigation shows that the continual use of the explosive welding in a drift may result in considerable damage on the drift.

• 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.

• Tunnel and Underground Space
• /
• v.22 no.1
• /
• pp.54-59
• /
• 2012

Deformation of Lead plate blast pressure meter were measured after they were exposed to surface blasting. Blasting pressure was determined by comparing the data with calibration graph which was drawn from the laboratory experiments with gas gun of Hopkinson bar tester. The results were compared with calculated values from the equations of CONWEP (Conventional Weapons Effects Program) and DDESB (Department of Defence Explosives Safety Board). Measured values were lower than calculated values in near field. Gradual decaying tendency of the pressure was observed. It means that estimated blasting pressure of very near field with theoretical equations can be uncertain.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.10 no.2
• /
• pp.69-75
• /
• 2007

So far, anti-piercing depths for concrete slabs have been determined using Conventional Weapon's Effects Program(CONWEP) that was developed by the U. S. Army's Corps of Engineering. However, it has been suggested by a number of field officers that the values computed by CONWEP tend to be too high for protective facilities used in small military units and that indiscriminate application of these values to such facilities would lead to uneconomical penetration-proof designs. In this study, gunshots onto RC slabs were carried out using KM80 bullets in order to measure the piercing depths. The observed depths and the depths offered by the CONWEP system differed greatly from each other by up to 119 centimeters. Based on the depth values obtained through this experiment, we have proposed a new equation to calculate effective anti-piercing depths for RC slabs against small caliber bullets.

• Structural Engineering and Mechanics
• /
• v.91 no.1
• /
• pp.63-73
• /
• 2024

Improving the blast resistance of structural establishments has become an imperative engineering commitment to prevent property damage and fatalities in terrorist incidents. This study investigates the effects of blast mass and stand-off distance on CFRP skin concrete core sandwich bunkers of varying thicknesses using ABAQUS/Explicit software with CONWEP functionality. The considered parameters include TNT masses of 1, 10, and 25 kg and stand-off distances of 0.1, 1, 2, and 2.5 meters on structures with 200, 250, and 500 mm core thicknesses. The study finds that there exists a declining response corresponding to the blasting mass reduction coupled with increases in the stand-off distance and core thickness. The 500 mm thick bunker sustains less damage compared to those with 200 mm and 250 mm core thicknesses. The sandwich configuration remains structurally advantageous vs. those without skins. The sandwich bunker with a 500 mm thick concrete core gives the best performance against the 10 kg TNT blast load with a 1 m standoff distance exhibiting a 22.8% reduction in damage vs. that without skins. Mathematical expressions are then formulated for predicting maximum von Mises stress, principal stress, and displacement of sandwich bunkers as functions of TNT masses, stand-off distances, and core thicknesses.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.313-318
• /
• 2008

The blast load is caused by gas or bomb explosions. In this study blast load was simulated using the computer code CONWEP and nonlinear analysis was performed on three-story steel moment frames. It was observed from the analysis results that the response of the structures varied depending on the opening area and the explosive weight.

• Journal of Korean Association for Spatial Structures
• /
• v.16 no.4
• /
• pp.117-123
• /
• 2016

The blast load is classified into free-air blast and surface blast following the location of explosion and surface. In this paper, several equations for blast load calculation are explained briefly and a modified equation for free-air blast load is suggested. The modified equation is based on Kingery-Bulmash equation which is used in UFC 3-340-02 and Conwep model. In this modified equation, the process of calculation is simplified against the original equation, and the number of coefficients is reduced under 5. As a result, each parameter of estimated data by modified equation has less than 1% of error range comparing with Kingery-Bulmash equation.