• Title/Summary/Keyword: High velocity projectile

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Impact-resistant design of RC slabs in nuclear power plant buildings

  • Li, Z.C.;Jia, P.C.;Jia, J.Y.;Wu, H.;Ma, L.L.
    • Nuclear Engineering and Technology
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    • v.54 no.10
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    • pp.3745-3765
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    • 2022
  • The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20-70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

Influence of Reinforced Fiber on Local Failure of the Concrete subjected to Impact of High-Velocity Projectile (고속 비상체 충돌에 의한 콘크리트의 국부파괴에 미치는 혼입 섬유의 영향)

  • Kim, Hong-Seop;Kim, Gyu-Yong;Choe, Gyeong-Cheol;Kim, Jung-Hyun;Lee, Young-Wook;Han, Sang-Hyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.11a
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    • pp.139-140
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    • 2014
  • The purpose of this study in to evaluate relationship between mechanical properties of materials and fiber type by reinforced fiber with high-velocity impact fracture behavior of fiber reinforced concrete. As a result, for fracture behavior by high-velocity impact, it is considered that impact fracture behavior is not affected by static mechanical properties directly but affected by fiber type and density of the number of fiber. It is necessary to consider type, shape, mechanical properties and the number of fiber with flexural and tensile performance for the evaluation on impact resistance performance of fiber reinforced concrete.

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Face Damage Characteristic of Steel Fiber-Reinforced Concrete Panels under High-Velocity Globular Projectile Impact (구형 비상체에 의한 충격하중을 받는 강섬유보강 콘크리트 패널의 손상특성)

  • Jang, Seok-Joon;Son, Seok-Kwon;Kim, Yong-Hwan;Kim, Gyu-Yong;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.27 no.4
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    • pp.411-418
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    • 2015
  • This paper investigates the effects of fiber volume fraction and panel thickness on face damage characteristics of steel fiber-reinforced concrete (SFRC) under high-velocity globular projectile impact. The target specimens were prepared with $200{\times}200mm$ prismatic panels with thickness of 30 or 50 mm. All panels were subjected to the impact of a steel projectile with a diameter of 20 mm and velocity of 350 m/s. Specifically, this paper explores the correlation between mechanical properties and face damage characteristics of SFRC panels with different fiber volume fraction and panel thickness. The mechanical properties of SFRC considered in this study included compressive strength, modulus of rupture, and toughness. Test results indicated that the addition of steel fiber significantly improve the impact resistance of conventional concrete panel. The front face damage of SFRC panels decreased with increasing the compressive toughness and rear face damage decreased as the modulus of rupture and flexural toughness increased. To evaluate the damage response of SFRC panels under high-velocity impact, finite element analysis conducted using ABAQUS/Explicit commercial program. The predicted face damage of SFRC panels based on simulation shows well agreement with the experimental result in similar failure mode.

High Velocity Impact Characteristics of Shear Thickening Fluid Impregnated Kevlar Fabric

  • Park, Yurim;Baluch, Abrar H.;Kim, YunHo;Kim, Chun-Gon
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.2
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    • pp.140-145
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    • 2013
  • The development of high performance fabrics have advanced body armor technology and improved ballistic performance while maintaining flexibility. Utilization of the shear thickening phenomenon exhibited by Shear Thickening Fluids (STF) has allowed further enhancement without hindering flexibility of the fabric through a process of impregnation. The effect of STF impregnation on the ballistic performance of fabrics has been studied for impact velocities below 700 m/s. Studies of STF-impregnated fabrics for high velocity impacts, which would provide a transition to significantly higher velocity ranges, are lacking. This study aims to investigate the effect of STF impregnation on the high velocity impact characteristics of Kevlar fabric by effectively dispersing silica nanoparticles in a suspension, impregnating Kevlar fabrics, and performing high velocity impact experiments with projectile velocities in the range of 1 km/s to compare the post impact characteristics between neat Kevlar and impregnated Kevlar fabrics. 100 nm diameter silica nanoparticles were dispersed using a homogenizer and sonicator in a solution of polyethylene glycol (PEG) and diluted with methanol for effective impregnation to Kevlar fabric, and the methanol was evaporated in a heat oven. High velocity impact of STF-impregnated Kevlar fabric revealed differences in the post impact rear formation compared to neat Kevlar.

A Study on the fracture behavior of surface hardening treated aluminum alloy under the high velocity impact (고속충격을 받는 표면처리된 알루미늄 합금의 거동에 관한 연구)

  • 손세원;김희재;황도연;홍성희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.784-789
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    • 2001
  • In order to investigate the fracture behaviors(penetration modes) and the resistance to penetration during ballistic impact of cold-rolled Al 5052 H34 alloy laminates, anodized Al 5052 H34 alloy laminates, and Al 5052 H34 alloy after cold-rolling, ballistic testing was conducted. In general, superior armor material is brittle materials which have a high hardness. Ballistic resistance of these materials was measured by protection ballistic limit(V50), a statical velocity with 50% probability for incomplete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are observed respectfully, resulting from V50 test and Projectile Through Plate(PTP) test at velocities greater than V50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V50 tests with 0$^{\circ}$obliquity at room temperature were also conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Surface Hardness, resistance to penetration, and penetration modes of Al 5052 H34 alloy laminates compared to those of cold-rolled Al 5052 H34 alloy laminates and anodized Al 5052 H34 alloy laminates anodized Al 5052 H34 alloy after cold-rolling.

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Design and Experiment of Coil gun to Apply Electomagnetic Launcher System (전자기 발사장치에 적용 가능한 코일건 설계 및 실험)

  • Lee, Su Jeong;Kim, Jin Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.6
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    • pp.3455-3459
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    • 2014
  • This paper reports the design and experiments for a high drive force of projectile in a coil gun system. Currently, the coil gun has been studied to apply an electromagnetic launcher. A coil gun launches a projectile by the attractive magnetic force of the electromagnetic coil. The drive force of projectile is proportional to the magnetic force generated by the electromagnetic coil. The current affects the life of the coil and the current limit exists. Therefore, the coil gun design, which does not exceed the current limit and the magnetic forces are at the maximum, is required. For this purpose, this study calculated the magnetic flux density and forces of the coil gun system and determined the current limit of the coil using the Onderdonk's equation. Based on the design result, a prototype was manufactured and an experiment was conducted to measure the muzzle velocity of the projectile. The fired projectile was analyzed using a CCD camera, and the muzzle velocity was 21m/s. In addition, a comparison of the experimental value and analysis value using commercial electromagnetic analysis software MAXWELL revealed an error of approximately 9.5%.

The experimental investigation for penetration depth and shape of aluminum alloy plates by 5.56mm ball projectile with striking velocities between 350 and 750㎧ (고속충격시 볼탄에 의한 알루미늄 합금의 관통 깊이와 형상에 관한 실험적 연구)

  • 손세원;김희재;김영태
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.800-803
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    • 2002
  • This investigation describes and analyses the experimental results proper to the penetration of Al5052-H34 alloy plates of thickness 6, 12 and 16mm(T/D=1, 2, 3) by 5.56mm ball projectiles over the velocity range 350-750㎧. All the high velocity impact tests were carried out at normal impact angle, i.e. zero obliquity. The experimental results presented the variation of depth of penetration, bulge height and diameter, plugged length and diameter with the velocity fur tests on each plate of a given thickness in order to determine the deformation shapes of 5.56mm ball projectiles and targets. Also the protection ballistic limit($V_50$) tests were conducted.

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Experimental Studies on Eye Injury Risks by Different BB Pellet Materials (BB Pellet 재질에 따른 안구 손상 위험성에 관한 실험적 연구)

  • Kim, Hyung-Suk;Park, Dal-Jae
    • Journal of the Korean Society of Safety
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    • v.27 no.2
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    • pp.20-24
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    • 2012
  • Experimental studies were performed to investigate the eye injury risks by different BB pellet materials. Four different BB pellet materials were used: plastic (P), silicon (S), rubber (R) and plastic covered with silicon (SR). The BB pellet images penetrating into the gelatine simulant were recorded by a high-speed video camera. The results obtained from the different pellet materials were discussed in terms of impact velocity and penetration depth; threshold velocity and projectile sectional density; eye injury risks by normalized energies. It was found that the P pellets caused higher impact velocity while the lower was SR pellets. The penetration depth and threshold velocity of the pellets were dependent on the impact velocity of the pellets, and the P pellets resulted in the higher eye injury risk while the lower was SP.

Influence Factor Analysis of Projectile on the Fracture Behavior of Aluminum Alloys Under High Velocity Impact with Latin Square Method (라틴방격법을 이용한 고속 충격 알루미늄합금의 파괴거동에 미치는 충격자 영향 분석)

  • Kim, Jong-Tak;Cho, Chang-Hee;Kim, Jin-Young;Kim, Tae-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.9
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    • pp.1021-1026
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    • 2011
  • Structural impact problems are becoming increasingly important for a modern defense industry, high-speed transportation, and other applications because of the weight reduction with high strength. In this study, a numerical investigation on the impact fracture behavior of aluminum plates was performed under various projectile conditions such as nose shapes, velocities, and incidence angles. In order to reduce the iterative numerical analysis, the Latin Square Method was employed. The influence factor was then determined by an FE analysis according to the conditions. The results were evaluated by means of a statistical significance interpretation using variance assessment. It was shown that the velocity and incidence angle can be the most important influence factors representing the impact absorption energy and plastic deformation, respectively.

Fracture Mechanism of Ceramic/Glass-fiber-reinforced-composites Laminate by High Velocity Impact (세라믹/유리섬유강화복합재 적층판의 고속충돌에 의한 파괴거동)

  • Jung Woo-Kyun;Lee Woo-Il;Kim Hee-Jae;Kwon Jeong-Won;Ahn Sung-Hoon
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.5 s.182
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    • pp.170-176
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    • 2006
  • Multi-layered laminate made of ceramic/composite have been developed to prevent penetration by high velocity impact. In this study, three-layered plates consisted of 1) cover layer (glass fiber reinforced polymer), 2) $Al_{2}O_{3}$, ceramic plate, and 3) backing plate (glass fiber reinforced polymer) were fabricated with various conditions and tested for their ballistic protection characteristic. The ceramic composite laminates, with thin backing plate, were completely penetrated by armor piercing projectile. The plate with inserted rubber between ceramic and backing plate showed excellent ballistic protection, though completely penetrated by the second shoot.