• Steel and Composite Structures
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• 제16권3호
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• pp.269-288
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• 2014

Experiments were carried out to investigate the ballistic performance of fiber reinforced plastic(FRP)-steel plates completely penetrated by hemispherical-nosed projectiles at sub-ordnance velocities greater than their ballistic limits. The FRP-steel plate consists of a front FRP laminate and a steel backing plate. Failure mechanisms and impact energy absorptions of FRP-steel plates were analyzed and compared with FRP laminates and single steel plates. The effects of relative thickness, manufacturing method and fabric type of front composite armors as well as the joining style between front composite armors and steel backing plates on the total perforation resistance of FRP-steel plates were explored. It is found that in the case of FRP-steel plates completely penetrated by hemispherical-nosed projectiles at low velocities, the failure modes of front composite armors are slightly changed while for steel backing plates, the dominate failure modes are greatly changed due to the influence of front composite armors. The relative thickness and fabric type of front composite armors as well as the joining style of FRP-steel plates have large effects whereas the manufacturing method of front composite armors has slight effect on the total perforation resistance of FRP-steel plates.

• 대한기계학회논문집A
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• 제36권12호
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• pp.1569-1575
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• 2012

본 논문은 AUTODYN-3D 프로그램을 이용한 방탄 헬멧의 탄도충격에 관한 연구를 하였다. 두 가지 유형의 재료가 방탄 헬멧에 사용되었다. Kevlar 및 Steel/Kevlar 혼합복합재 이다. 강구와 7.62 mm 금속피복탄이 시뮬레이션에서 사용되었다. 시뮬레이션에서 발사체의 변형된 형상과 내부에너지가 계산되었다. 결과는 Steel/Kevlar 헬멧을 관통하기 위해 요구되는 충격속도는 강구와 7.62 mm 금속피복탄에 따라 각각 655 m/s 와 845 m/s 이상이다. 결과로부터 Kevlar 와 Steel/Kevlar 헬멧 사이의 탄도 저항에 큰 차이를 볼 수 있었다. NIJ-STD-0106.01 Type II헬멧에 대한 시뮬레이션으로 충격 속도 358 m/s 의 7.62 mm 금속피복탄이 사용되었다. 시뮬레이션 결과는 Steel/Kevlar 헬멧이 충격 속도 358 m/s 의 7.62 mm 금속피복탄을 방어할 수 있는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제40권5호
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• pp.595-616
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• 2011

Impact experiments have been carried out on concrete slabs. The first group was traditionally manufactured, densely reinforced concrete targets, and the next were ordinary Portland and calcium aluminate cement based HPSFRC (High performance steel fiber reinforced concrete) and SIFCON (Slurry infiltrated concrete) targets. All specimens were hit by anti-armor tungsten projectiles at a muzzle velocity of over 4 Mach causing destructive perforation. In Part I of this article, production and experimental procedures are described. The first group of specimens were ordinary CEM I 42.5 R cement based targets including only dense reinforcement. In the second and third groups, specimens were produced using CEM I 42.5 R cement and Calcium Aluminate Cement (CAC40) with ordinary reinforcement and steel fibers 2 percent in volume. In the fourth group, SIFCON specimens including 12 percent of steel fibers without reinforcement were tested. A high-speed camera was used to capture impact and residual velocities of the projectile. Sample tests were performed to obtain mechanical properties of the materials. In the companion Part II of this study, numerical investigations and simulations performed will be presented. Few studies exist that examine high-velocity impact effects on CAC40 based HPSFRC targets, so this investigation gives an insight for comparison of their behavior with Portland cement based and SIFCON specimens.

• 한국전산구조공학회논문집
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• 제34권2호
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• pp.85-91
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• 2021

본 연구에서는 섬유보강콘크리트(SFRC) 구조물의 수치해석을 위한 K&C모델의 보정기법을 소개하였다. SFRC 1축 및 3축 압축강도 실험결과를 기반으로 보정을 수행하였으며, 단일요소 해석결과를 실험결과와 비교함으로써 보정 기법의 검증을 수행하였다. 또한, 변형률 속도의 영향을 반형하기 위해 동적증가계수(DIF)를 고려하여 SFRC 구조물의 발사체 관통해석을 수행함으로써 보정기법의 적용 가능성을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.331-336
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• 2004

This paper is concerned with numerical simulation of hypervelocity impacts(HVIs) of a projectile on laminated composite plate targets using SPH method. A one-parameter visco-plasticity model and damage model is used to describe the HVIs response of composite materials. The numerical simulation was carried out for a steel projectile striking to aluminum plate targets and for an aluminum projectile striking to laminated graphite/epoxy (Gr/Ep) composite plate targets. Through the numerical simulation, comparison with the HVIs response of isotropic materials and composite materials is discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.55-60
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• 2004

This study is concerned to the perforation phenomena of the oblique dual-plate by projectile. Experiment and simulation related to that was carried out. the variables considered in this phenomena include the electrolytic zinc coated steel sheet and carbon steel rod. In the former, the confirmation and projectile velocity possible phenomena of real phenomena is done, the latter, the effect of parameter such as time-step and grid space length is analized by using the three-dimensional Lagrangian explicit time-integration finite element code, HEMP. this code use the eight node hexahedral elements and in this study, Von-Mises Criteria is used as the strength model, Mie-Gruneisen is as the Equation of State. the simulation was performed by contrast with the experiment. through the calibration of the parameter of lagrangian code, reasonable result was approached.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.389-390
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• 2009

최근 폭탄테러 등에 의한 건축구조물의 피해 및 2차적인 인적 물적 피해가 증가하고 있다. 따라서 본 연구에서는 고속 비상체의 충격시험에 의한 섬유보강콘크리트의 내충격 성능평가를 실시하여 내충격 성능의 향상을 위한 기초자료를 제시하는데 목적을 두고 있다.

• Structural Engineering and Mechanics
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• 제82권5호
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• pp.587-594
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• 2022

Behavior of concrete elements under the effect of high-speed projectiles has gain increasing interest recently. It's necessary to understand how far the concrete can absorb the effect of bullets in order to save the occupants when design security and military infrastructures. This study presents a total of 18 concrete slabs casted and tested under reinforcement ratios, 0%, 0.35% and 0.7%. Parameters interested were slab thickness, (50 mm, 100 mm, and 150 mm) and type of weapon. All specimens tested to investigate their response under the effect of attacking by two common types of weapon. In general, it was found that projectile penetration was controlled by their thickness regardless the steel reinforcement ratio. However, the steel reinforcement controls the damage.

• Steel and Composite Structures
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• 제22권4호
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• pp.777-796
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• 2016

In this paper, the behavior of woven E-glass fabric composite laminate was experimentally investigated under quasi-static indentation and high velocity impact by flat-ended, hemispherical, conical (cone angle of $37^{\circ}$ and $90^{\circ}$) and ogival (CRH of 1.5 and 2.5) cylindrical perforators. Moreover, the results are compared in order to explore the possibility of extending quasi-static indentation test results to high velocity impact test results in different characteristics such as perforation mechanisms, performance of perforators, energy absorption, friction force, etc. The effects of perforator nose shape, nose length and nose-shank connection shapes were investigated. The results showed that the quasi-static indentation test has a great ability to predict the high velocity impact behavior of the composite laminates especially in several characteristics such as perforation mechanisms, perforator performance. In both experiments, the highest performance occurs for 2.5 CRH projectile and the lowest is related to blunt projectiles. The results show that sharp perforators indicate lower values of dynamic enhancement factor and the flat-ended perforator represents the maximum dynamic enhancement factor among other perforators. Moreover, damage propagation far more occurred in high velocity impact tests then quasi-static tests. The highest damage area is mostly observed in ballistic limit of each projectile which projectile deviation strongly increases this area.

• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.190-205
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• 2015

In this paper, the impact damage behavior of USN-150B carbon/epoxy composite laminates subjected to high velocity impact was studied experimentally and numerically. Square composite laminates stacked with $[45/0/-45/90]_{ns}$ quasi-symmetric and $[0/90]_{ns}$ cross-ply stacking sequences and a conical shape projectile with steel core, copper skin and lead filler were considered. First high-velocity impact tests were conducted under various test conditions. Three tests were repeated under the same impact condition. Projectile velocity before and after penetration were measured by infrared ray sensors and magnetic sensors. High-speed camera shots and C-Scan images were also taken to measure the projectile velocities and to obtain the information on the damage shapes of the projectile and the laminate specimens. Next, the numerical simulation was performed using explicit finite element code LS-DYNA. Both the projectile and the composite laminate were modeled using three-dimensional solid elements. Residual velocity history of the impact projectile and the failure shape and extents of the laminates were predicted and systematically examined. The results of this study can provide the understanding on the penetration process of laminated composites during ballistic impact, as well as the damage amount and modes. These were thought to be utilized to predict the decrease of mechanical properties and also to help mitigate impact damage of composite structures.