• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.503-510
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• 2015

In this paper, the blast resisting performance of partially reinforced CFT columns was compared with the normal CFT columns to evaluate the effect of reinforcing with steel plates. Autodyn which is a specialized hydro-code for analysis of explosion and impact was used to simulate the structural behavior of the CFT columns under the blast loadings. The interaction between concrete and surrounding steel plates was modeled with friction and join option to represent the realistic damage of columns. According to the analysis, the partially reinforced CFT column showed enhanced blast resisting performance than the normal CFT columns. Also the improvement of blast resisting performance was depended on the height of reinforcing steel plates.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.275-284
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• 2022

Linear Shaped Charge(LSC) is widely used as a separation system in the field of weapon system. However, there are some disadvantages that are charging lots of explosives due to lack of uniformity and having difficulties of the design of liner and explosives because of manufacturing process. In order to solve these problems, Precision Linear Shaped Charge(PLSC) that can design a liner independently and charge explosives uniformly has been developed. In this study, PLSC was designed to have a proper liner shape and amount of explosives, and the penetration test of PLSC with different stand-off distance from liner to target was conducted. On the basis of the penetration test results of PLSC, the numerical analysis method using AUTODYN was established and verified. The penetrative mechanism and characteristics of PLSC with targets of different materials was analyzed from experimental and numerical results.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.102-114
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• 2004

The present work has been developed the interpretation processor including the behavior of material failure and the separation phenomena under transient dynamic loading (the operation of explosive bolt) using AUTODYN V4.3, SoildWork 2003 and TrueGrid V2.1 programs. It has been demonstrated that the interpretation in ridge-cut explosive bolt under dynamic loading condition should be necessary to the appropriate failure model and the basic stress of bolt failure is the principal stress. The use of this interpretation processor developing the present work could be extensively helped to design the shape and the amount of explosives in the explosive bolt having a complex geometry. It is also proved that the interpretation processor approach is an accurate and effective analysis technique to evaluate the separation mechanism in explosive bolts.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.191-198
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• 2017

To study the behavior of structures subject to blast loads it is important to calculate the loads due to the explosives accurately, especially in the case of interior explosions. It is known that numerical method based on computational fluid dynamics can estimate relatively accurate blast load due to the interior explosion including reflection effect. However, the numerical method has disadvantages that it is difficult to model the analysis and it takes much time to analyze it. Therefore, in this study, the analytical method which can include the reflection effect of the interior explosion was studied. The target structures were set as the slabs of residential buildings subject to interior explosion that could lead to massive casualties and progressive collapses. First, the numerical method is used to investigate the interior explosion effect and the maximum deflection of the slab which was assumed to be elastic, and compared with the analytical method proposed in this study. In the proposed analytical method, we determine the weighting factor of the reflection effect using the beam theory so that the explosion load calculation method becomes more accurate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.4
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• pp.269-275
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• 2020

An explosive bolt is one of many representative pyrotechnic release devices that separates two joined structures using explosives inside the bolt. In this study, a 1/2 inch ridge-cut explosive bolt with an EBW detonator was developed for usage in sled tests. The initial shape design was carried out based on the design method, and the performance test showed that the separation performance was outstanding but fragments occurred. Therefore, numerical analysis was performed to reduce the amount of debris by minimizing the amount of explosives. From the numerical analysis, the separation mechanism and characteristics of the ridge-cut explosive bolts were identified, and the minimum amount of explosives that does not generate debris was proposed. Verification tests revealed that the ridge-cut explosive bolts with the proposed explosive weight minimized fragments while maintaining the separation performance.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.715-722
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• 2014

In this paper, internal blast effect of reinforced concrete core structure were investigated using Ansys Autodyn, which is a specialized hydrocode for the analysis of explosion and impact. It is expected that internal blast case can give additional damage to the structure because it causes rebound of blast loads. Therefore, in this paper, the hazard of internal blast effect is demonstrated using UFC 3-340-02 criteria. In addition, analysis result of Autodyn, experimental result regarding rebound of blast load, and example of UFC 340-02 are compared to verify that Autodyn can analyze internal blast effect properly. Furthermore, progressive collapse mechanism of core structure which is one of the most important parts in high rise buildings is also analyzed using Autodyn. When internal blasts are loaded to core structure, the core structure is mostly damaged on its corner and front part of core wall from explosives. Therefore, if the damaged parts of core wall are demolished, progressive collapse of the core structure can be initiated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.397-404
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• 2019

Linear Shaped Charge (LSC) that is widely used as separation system in aerospace system has to charge lots of explosives due to lack of uniformity. In addition, it is hard to optimize shape of liner and explosives because of manufacturing process. In order to overcome aforementioned drawbacks, Precision Linear Shaped Charge (PLSC) is currently under development. PLSC is made in two steps: prepare liner independently and charge explosive uniformly. In this study, PLSC is designed to have proper amount of explosives and penetration test of PLSC with different stand-off distance from liner to target is conducted to confirm penetration performance. Based on the penetration test results of PLSC, the numerical analysis method using AUTODYN is established and verified. Penetration mechanism and characteristics of PLSC is analyzed from the numerical and experimental results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.141-148
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• 2022

In this study, the structural behavior of reinforced concrete members under simultaneous axial and blast loads was analyzed. Nonlinear dynamic analysis verification was performed using the experimental data of panels under fundamental blast load as well as those of reinforced concrete columns subjected to axial and blast loads. Because Autodyn is a program designed only for dynamic analysis, an analysis process is devised to simulate the initial stress state of members under static loads, such as axial loads. A total of 80 nonlinear dynamic finite element analysis procedures were conducted by selecting parameters corresponding to axial load ratios and scaled distances ranging 0%~70% and 1.1~2.0 (depending on the equivalent of TNT), respectively. The structural behavior was compared and analyzed with the corresponding degree of damage and maximum lateral displacement through the changes in axial load ratio and scaled distance. The results show that the maximum lateral displacement decreases due to the increase in column stiffness under axial loads. In view of the foregoing, the formulated analysis process is anticipated to be used in developing blast-resistant design models where structural behavior can be classified into three areas considering axial load ratios of 10%~30%, 30%~50%, and more than 50%.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.67-74
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• 2016

Explosive bolt is one of separation device that uses high explosive charge, and is separated by pressure formed by an explosion and the resulting shock waves. Explosive bolt having such a mechanism would have to be designed to minimize shock and debris formation generated during separation. In this study, separation tests were carried out with distance as variable for restraining the explosive bolt (Air Gap). Bolt release and its separating shape with variation of air gap is observed, and we used accelerometer to measure the shock wave transmitted through a bound object. In addition, separation behavior of explosive bolt is analyzed using ANSYS AUOTODYN program. By comparing the results of previously performed experiments and analysis, we could confirm the effects of air gap to the release behavior of explosive bolt, and decide optimum constraining environment for specific separation bolts.