• 한국군사과학기술학회지
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• 제15권3호
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• pp.350-357
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• 2012

The velocity response of stiffened rectangular plate under high velocity impact was studied. Numerical simulation was conducted on the stiffened plate with four stiffeners under various impact positions. Considered stiffener types were rib, I, hat and T stiffener. For the center impact position of I stiffened plate, the simulated residual velocity was 365.6 m/s with the initial projectile velocity 500 m/s. The reinforcing characteristic of I stiffened plate was excellent among four stiffeners.

• 한국건축시공학회지
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• 제12권4호
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• pp.377-385
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• 2012

In this study, the Impact resistance of steel fiber and organic fiber reinforced concrete and mortar was evaluated and the improvement in toughness resulting from an increase in compressive strength and mixing fiber for impact resistance on performance was examined. The types of fiber were steel fiber, PP and PVA, and these were mixed in at 0.1, 0.5 and 1.0 vol.%, respectively. Impact resistance is evaluated with an apparatus for testing impact resistance performance by high-speed projectile crash by gas-pressure. For the experimental conditions, Specimen size was $100{\times}100{\times}20$, 30mm ($width{\times}height{\times}thickness$). Projectile diameter was 7 and 10 mm and impact speed is 350m/s. After impact test, destruction grade, penetration depth, spalling thickness and crater area were evaluated. Through this evaluation, it was found that as compressive strength is increased, penetration is suppressed. In addition, as the mixing ratio of fiber is increased, the spalling thickness and crater area are suppressed. Organic fibers have lower density than the steel fiber, and population number per unit area is bigger. As a result, the improvement of impact resistance is more significant thanks to dispersion and degraded attachment performance.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.263-266
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• 2007

Ballistic Range는 오래전부터 짧은 시간에 극도의 고압상태를 만들어낼 수 있기 때문에 고속 충격역학, 발사체 공기역학, 새로운 재료의 생성과 같은 다양한 공학 분야에서 사용되어왔다. 2단 경 가스총은 가장 넓게 사용되어지고 있다. 현재의 실험적 연구는 발사체 가상실험을 쉽게 수행할 수 있는 새로운 타입의 Ballistic Range를 개발하기위해 진행되어져왔다. 실험은 발사체 속도의 다양한 변수들의 의존성을 찾기 위해 수행되었다. 다양한 발차에 속도를 얻기 위해 고압실압력, 격막파열압력, 발사체와 피스톤 질량에 변화를 주었다. 또한 발사되는 발사체 주변의 유동을 알아보기 위해 유동장을 가시화하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.65-66
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• 2015

In this study, it evaluate mecahnical performance and impact resistance performance of fiber reinforced concrete, fiber reinforced mortar and preplace grout mortar. steel fiber, nylon fiber and polypropylene fiber are reinforced 1vol.% 2vol.% 10vol.% by each fiber type. It evaluate impact resistance performance to use projectile 10mm of 400m/s velocity. As a result, mechnical performance and impact resistance performance of fiber reinforced preplace grout mortar are improved a lot by 10% fiber reinforced ratio.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.877-888
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• 2021

The water entry behaviors of projectiles with different cone-headed angles were studied numerically, experimentally and theoretically, mainly focusing on the hydrodynamic impact in the initial stage. Based on MMALE algorithm, it was proposed a formula of impact deceleration, which relied on the initial entry velocity and cone-headed angle. Meanwhile, in order to verify the validity of the simulation model, experiments using accelerometer and high-speed camera were carried out, and their results were in a good agreement with simulation results. Also, theoretical calculation results of cavity diameter were compared with experiments and simulation results. It was observed that the simulation method had a good reliability, which would make forecast on impact deceleration in an engineering project.

• Composites Research
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• 제23권6호
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• pp.14-18
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• 2010

우주 구조물을 위협하는 여러 요소들 중 MMOD(MicroMeteoroid and Orbital Debris)는 약 8~70km/s의 속도로 우주 구조물과 충돌하여 큰 피해를 주고 있다. 이러한 피해로부터 우주 구조물을 보호하기 위해서 현재 다양한 위플 쉴드가 연구, 적용되고 있다. 위플 쉴드에는 알루미늄이 주로 사용되고 있지만, 복합재료의 시용도 증가하고 있어 본 연구에서는 알루미늄과 복합 재료의 초고속 충돌 특성을 유한 요소 해석을 통해 비교하였다. 충격체는 직경 5.5mm인 알루미늄 2017-T4의 구를 사용하였고, 알루미늄 평판은 6061-T6, CFRP 평판은 T300/5208을 사용하였다. 충격체의 초기 충돌 속도는 1km/s이다. 충돌 후 충격체의 운동에너지는 알루미늄 평판의 경우 약 64J 감소하였고, CFRP 평판의 경우 약 63J 감소하였다. 비슷한 충돌 에너지 흡수 정도를 보이고 있지만, 밀도를 비교해 보았을 때 CFRP가 약 1.7배 가볍기 때문에 방탄 특성이 더 좋다고 할 수 있다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.254-255
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• 2017

The aim of this study is to investigate the impact resistant performance of steel short fiber-reinforced cement based composites (SFRCCs) containing 1.0, 1.5, 2.0 and 3.0% volume fraction of steel short fibers subjected to high velocity impact of steel projectile (the diameter of 19.05mm and the mass of 28.13g). The gunpowder impact facility was used for impact tests, and the impact velocity was from about 350 to 700m/s. The specimens were damaged in various failure modes, which are penetration, scabbing, and perforation. Comparing with Plain specimen, SFRCCs have superior capacity on the scabbing limit, and slightly bulged in the back side under the impact velocity of 700m/s. In addition, the impact resistant performance of SFRCCs improved with increase of steel short fiber volume ratio. The fibers play an important role in controlling the local damage of SFRCCs.

• Structural Engineering and Mechanics
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• 제77권3호
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• pp.329-342
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• 2021

In this paper, the effect of different steel bar configurations on the quasi-static punching and impact response of concrete slabs was studied. A total of forty RC square slab specimens were cast in two groups of concrete strengths of 40 and 63 MPa. In each group of twenty specimens, ten specimens were reinforced at the back face (singly reinforced), and the remaining specimens were reinforced on both faces of the slab (doubly reinforced). Two rebar spacing of 25 and 100 mm, with constant reinforcement ratio and effective depth, were used in both singly and doubly reinforced slab specimens. The specimens were tested against the normal impact of cylindrical projectiles of hemispherical nose shape. Slabs were also quasi-statically tested in punching using the same projectile, which was employed for the impact testing. The experimental response illustrates that 25 mm spaced rebars are effective in (i) decreasing the local damage and overall penetration depth, (ii) increasing the absorption of impact energy, and (iii) enhancing the ballistic limit of RC slabs. The ballistic limit was predicted using the quasi-static punching test results of slab specimens showing a strong correlation between the dynamic perforation energy and the energy required for quasi-static perforation of slabs.

• Structural Engineering and Mechanics
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• 제71권2호
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• pp.109-118
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• 2019

This paper presents the numerical simulation of membrane structure under impact load. Firstly, the numerical simulation model is validated by comparing with the test in Hao's research. Then, the effects of the shape of the projectile, the membrane prestress and the initial impact speed, are investigated for studying the dynamic response and failure mechanism, based on the membrane displacement, projectile acceleration and kinetic energy. Finally, the results show that the initial speed and the punch shape are related with the loss of kinetic energy of projectiles. Meanwhile, the membrane prestress is an important factor that affects the energy dissipation capacity and the impact resistance of membrane structures.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.417-428
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• 2020

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part III, the local damage of the rigid components of aircraft, e.g., engine and landing gear, impacting the steel concrete (SC) structures of NPP containment is mainly discussed. Two typical SC target panels with the thicknesses of 40 mm and 100 mm, as well as the steel cylindrical projectile with a mass of 2.15 kg and a diameter of 80 mm are fabricated. By using a large-caliber air gas gun, both the projectile penetration and perforation test are conducted, in which the striking velocities were ranged from 96 m/s to 157 m/s. The bulging velocity and the maximal deflection of rear steel plate, as well as penetration depth of projectile are derived, and the local deformation and failure modes of SC panels are assessed experimentally. Then, the commercial finite element program LS-DYNA is utilized to perform the numerical simulations, by comparisons with the experimental and simulated projectile impact process and SC panel damage, the numerical algorithm, constitutive models and the corresponding parameters are verified. The present work can provide helpful references for the evaluation of the local impact resistance of NPP buildings against the aircraft engine.