• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.28-31
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• 2005

The numerical simulation is conducted for analysis flame structure of superdetonative ram accelerator experiment by ISL(French-German Research Institute in Saint Louis). Fully coupled chemically non-equilibrium Navier-Stokes equation is used. Shockwave structure of superdetonative ram accelerator and behavior of detonation wave is studied. Maintaining of detonation wave is very important to accelerate projectile, Because detonation wave make high pressure gases and this high pressure accelerate projectile.

• 한국군사과학기술학회지
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• 제6권2호
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• pp.65-72
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• 2003

Composite sabot can increase the penetration performance of APFSDS projectile by reduction of the sabot weight. However, it has a thick-sectioned lamination and the lamination structure is different from those of the conventional composite parts. In this study, modeling technique for a thick and radially-laminated composite part has been applied in the finite element analysis of composite sabot. Four models of composite lamination for the sabot have been proposed and evaluated for their structural strength.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.325-326
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• 2004

Experiment of laser propulsion in free flight has never been conducted. At Institute of Fluid Science (IFS), Tohoku University, propulsive impulse generation by focusing on a rest projectile was demonstrated. Based on the ideas obtained from this experiment, experiment of laser propulsion of a projectile in flight by focusing $CO_2$ laser beam is being prepared for. The objective velocity increment in experiment is about 50 m/s.

• Computers and Concrete
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• 제7권2호
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• pp.119-143
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• 2010

This paper presents results from a study concerning the capability afforded by the RKPM (reproducing kernel particle method) meshfree analysis formulation to predict responses of concrete and UHPC components resulting from projectile impacts and blasts from nearby charges. In this paper, the basic features offered by the RKPM method are described, especially as they are implemented in the analysis code KC-FEMFRE, which was developed by Karagozian & Case (K&C).

• Computers and Concrete
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• 제16권6호
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• pp.933-961
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• 2015

Damage by high-speed impact fracture is a dominant mode of failure in several applications of concrete structures. Numerical modelling can play a crucial role in understanding and predicting complex fracture processes. The commonly used mesh-based Finite Element Method has difficulties in accurately modelling the high deformation and disintegration associated with fracture, as this often distorts the mesh. Even with careful re-meshing FEM often fails to handle extreme deformations and results in poor accuracy. Moreover, simulating the mechanism of fragmentation requires detachment of elements along their boundaries, and this needs a fine mesh to allow the natural propagation of damage/cracks. Smoothed Particle Hydrodynamics (SPH) is an alternative particle based (mesh-less) Lagrangian method that is particularly suitable for analysing fracture because of its capability to model large deformation and to track free surfaces generated due to fracturing. Here we demonstrate the capabilities of SPH for predicting brittle fracture by studying a slender concrete structure (column) under the impact of a high-speed projectile. To explore the effect of the projectile material behaviour on the fracture process, the projectile is assumed to be either perfectly-elastic or elastoplastic in two separate cases. The transient stress field and the resulting evolution of damage under impact are investigated. The nature of the collision and the constitutive behaviour are found to considerably affect the fracture process for the structure including the crack propagation rates, and the size and motion of the fragments. The progress of fracture is tracked by measuring the average damage level of the structure and the extent of energy dissipation, which depend strongly on the type of collision. The effect of fracture property (failure strain) of the concrete due to its various compositions is found to have a profound effect on the damage and fragmentation pattern of the structure.

• 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.

• 한국항공우주학회지
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• 제41권10호
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• pp.796-804
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• 2013

연소 및 추진 기관 공학 교육 과정의 일부로써 간단한 형태의 열기관인 감자총 (Potato Gun)의 제작, 시험 및 해석을 수행하였다. 정적 연소실의 화학 평형 해석을 이용하여 연소실의 압력을 계산하고, 팽창과정의 열역학 해석을 통하여 열에너지의 운동에너지로 변환되는 내탄도 과정을 계산하였다. 공기역학적 지식을 도입한 구형 탄도 궤적 해석을 통하여 비행거리를 추정할 수 있었으며, 이를 통하여 감자총의 에너지 변환 효율 및 혼합기의 당량비를 추정하였다. 본 과제는 재활용 자재를 이용하여 학부 수준에서 열-유체역학공학 지식을 활용하여 실습하고 학생들의 관심을 유발할 수 있는 적당한 예로 여겨진다.

• 한국항공우주학회지
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• 제39권5호
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• pp.385-390
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• 2011

본 연구의 목적은 풍동시험을 통해 회전발사체에서 발생하는 동적 마그너스 효과를 실험적으로 측정하는데 있었으며, 이를 위해 약 12,000 rpm으로 회전하는 155-mm 회전발사체 실험모형에 작용하는 마그너스 특성의 측정을 위한 고속풍동실험을 국방과학연구소 삼중음속풍동에서 수행하였다. 실험시의 마하수는 0.7~2.0까지였으며 이때의 받음각 구간은 -4~+10 deg이었다. 풍동실험 측정기법의 유효성 평가를 위해 동일형상 모형에 대해 기 수행하였던 마그너스 측정결과와의 비교검토를 수행하였으며, 기존 연구결과들과 잘 부합됨을 확인하였다.

• 한국자기학회지
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• 제25권3호
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• pp.87-91
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• 2015

본 논문에서는 코일건 발사 시스템의 성능 향상을 위한 솔레노이드 설계에 대해 연구하였다. 즉, 코일건 솔레노이드의 코일 직경에 따른 피투사체의 발사속도에 대한 분석을 수행하였다. 코일건은 자기력을 이용하여 피투사체를 발사시키는 시스템이다. 솔레노이드에 순간적으로 큰 전류를 흘려주면 코일 주위에 순간적인 자기장이 만들어지고, 발사체는 플레밍의 오른손 법칙에 따라 코일의 중심 방향으로 자기력을 받아 발사된다. 피투사체의 발사 속도는 솔레노이드 코일이 생성하는 자기력과 비례한다. 하지만, 솔레노이드 코일은 규격에 따른 최대허용 전류가 존재한다. 따라서, 한계 전류 내에서 피투사체에 작용하는 자기력이 최대가 되는 솔레노이드 코일의 설계가 필요하다. 본 논문에서는 솔레노이드 코일의 설계를 위해 AWG(American Wire Gauge)6부터 AWG18까지의 코일의 직경에 따른 최적의 권수를 찾아서 발사가능여부와 그에 따른 발사속도를 비교 분석한다.

• Computers and Concrete
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• 제9권4호
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• pp.311-325
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• 2012

In this paper, we examine the behavior of the High-Rate Brittle Microplane (HRBM) concrete model based on a series of penetration experiments. These experiments were conducted with three different slab thicknesses (127, 216 and 254 mm) that provided a significant challenge for the numerical simulations. The 127 mm slab provided little resistance, the 216 mm slab provided nominal resistance and the 254 mm slab approached the perforation limit thickness of the projectile. These experiments provide a good baseline for evaluating material models since they have been shown to be extremely challenging; in fact, we have not encountered many material models that can provide quantitatively predictive results in terms of both projectile exit velocity and material damage. In a companion paper, we described the HRBM material model and its fit to various quasi-static material property data for WES-5000 concrete. In this paper, we show that, when adequately fit to these quasi-static data, the HRBM model does not have significant predictive capabilities, even though the quasi-static material fit may be exceptional. This was attributed to the rate-dependent response of the material. After various rate effects were introduced into the HRBM model, the quantitative predictive nature of the calculations dramatically increased. Unfortunately, not much rate-dependent material property data are in the literature; hence, accurate incorporation of rate effects into material models is difficult. Nonetheless, it seems that rate effects may be critical in obtaining an accurate response for concrete during projectile perforation events.