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주재현,최준홍,이헌주,이창현,Joo, Jae-Hyun,Choi, Joon-Hong,Lee, Heon-Joo,Lee, Chang-Hyun 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.5
In this study, a series of ballistic experiments have been performed to investigate the protection mechanism of some inert reactive cassettes against shaped charge jet. Three kinds of material were tested as a core material of the inert cassettes, i.e. one of rubber materials, a high modulus and high strength composite material used for ballistic protection and a mixture of energetic materials. Parameters such as deformation of the cassettes, occurrence time of jet distortion, leading jet length and residual penetration depth were investigated from the experiments and they were compared to each other quantitatively according to the jet incidence angles. The results show that the increment of cassette deformation caused jet distortion to occur early and jet distortion brought decrease of the length of leading jet. Then the decrease of the length of leading jet accompanied the decrease of residual penetration depth.
박성수(Sung Su Park),정윤철(Yoon Chul Jung),최준홍(Joon Hong Choi),신형섭(Hyung Seop Shin) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4
고 변형률속도하에서 고무기 재료의 변형거동의 이해는 방호체계나 장갑과 같은 충격에 잘 견딜 수 있어야 하는 분야에서 중요하게 여겨지고 있다. 본 연구의 목적은 테일러 충격시험 동안 고무기 재료들의 총체적인 변형거동을 조사하는 것이다. 테일러 충격시험은 20 ㎜ 에어건을 사용하여 충격속도 150~250 m/s의 범위에서 수행되었다. 8 채널의 고속영상장치는 충격시험 동안 고무기 재료 발사체의 변형거동을 일련의 사진으로 제시한다. 선택된 재료들에 따라 다양한 변형과 파괴거동을 보여주고 있다 게다가, 충격 동안 고속영상장치로부터 얻어진 사진을 바탕으로 변형된 발사체 형상을 영상데이터화 함으로써 동적 변형의 양적인 접근이 가능하게 되었다. 그리고, 고무기 재료들의 동적 강도에 대한 첨가제의 영향 또한 조사하였다. The understanding of the deformation behavior of rubber materials under high loading-rate conditions will be important considering in their impact-resistant applications such as protective shields and transparent armor. The objective of this work is to investigate the overall deformation behavior of rubber materials during Taylor impact test. Taylor impact tests of rubber materials were carried out in the velocity range between 150~250 m/s using the 20 ㎜ air gun. A 8-ch High-speed photography system provided a series of images representing the deformation behavior of rubber projectile during impact. Depending on materials adopted, they showed a variety in deformation and fracture behaviors. Additionally, the quantitative approach of dynamic deformation analysis through digitizing the deformed shape of projectile using high-speed photographs taken during impact was tried. The influence of additive filler on the dynamic strength of rubber materials will be also examined.
Taylor 충격시험을 통한 고무기 재료의 동적 점탄성물성의 동정
박성수(Sung Su Park),신형섭(Hyung Seop Shin),최준홍(Joon Hong Choi) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The understanding of the deformation behavior of rubber materials under high loading-rate conditions will be important considering in their impact-resistant applications such as protective shields and transparent armor. Recently we have been investigated the dynamic deformation behavior of rubber materials including viscoelastic during Taylor impact tests incorporated with high-speed photography system. Through the experiment, it was possible to depict the overall deformation behavior, but it is difficult to determine specifically the viscoelastic properties. The objective of this study is to couple the numerical simulation process to identify the dynamic viscoelastic properties based on the experimental. Experimentally obtained data was compared with ones obtained AUTODYN-2D simulation. Through the numerical simulation, the behavior at higher impact velocity can be predicted. Also, it was made possible to understand the dynamic behavior of rubber materials during impact.
Taylor Impact Test시 고속 카메라 영상을 사용한 폴리머 재료의 동적 거동 해석
박성택(Sung-Taek Park),박정수(Jung-Soo Park),신형섭(Hyung-Seop Shin),최준홍(Joon-Hong Choi),김정태(Jeong-Tae Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
To evaluate dynamic material properties of metallic materials at high-strain-rate. several one-dimensional models using recovered projectiles by Taylor Impact tests have been developed. However, for polymeric materials, the models can not be used as developed because polymers show significant elastic and anelastic deformation. This limitation could be released by incorporating the high-speed photography technique with Taylor impact tests in the range of impact velocity from 150 to 350 m/s. A series of photographs made it possible to depict the deformation pattern and to measure instantaneous diameter along the projectile length. In addition, it gave a relationship between the deformation length and the elapsed time which make possible to calculate a strain rate at an instant of deformation. The strain rate dependance of the dynamic yield stress in thermoplastic materials of PE, PC and PEEK can be determined by rod impact test in the strain-rate range of 10³~10⁴ sec?¹.
박성택(Sung-Taek Park),신형섭(Hyung-Seop Shin),박정수(Jung-Soo Park),최준홍(Joon-Hong Choi),김정태(Jeong-Tae Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
The deformation of polymers under high loading-rate conditions will be a governing factor to be considered in their impact-resistant applications such as protective shields and transparent armor. In this paper, the deformation and fracture behaviors of polymeric materials such as PE, PC and PEEK have been investigated by Taylor Impact tests. Taylor cylinder impact tests and high speed photography are introduced to examine the deformation behavior under dynamic loading condition. 20 ㎜ air gun was used to perform the impact experiments. Cylindrical projectiles have been impacted onto a hardened steel anvil at a velocity ranging from 100 to 350 ㎳?¹. Along the barrel line, a photo-sensor which measures the speed of the projectile, four digital cameras which has shutter speed of 1/917,000sec and a rigid anvil were set up. After impact experiments, the shapes of projectiles and images taken using high speed cameras were analysed. Depending on materials adopted, they showed a variety in deformation and fracture behaviors.
Ti-6Al-4V 합금의 동적변형특성과 탄도충격성능 : 1. 초고속 폭발충격 특성 1. Ultra-high-speed Exploding Properties
이유환,이동근,이성학,이종수,최준홍,허선무 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.10
The effects of microstructural morphology on ultra-high-speed exploding properties of Ti-6Al-4V alloy were investigated in this study. Exploding bridge wire (EBW) test was conducted on equiaxed and bimodal microstructures, which were processed by different heat treatments. From the test, moving velocity of free surface vs time profiles were obtained to measure strength at Hugoniot elastic limit (HEL) and spall strength and to subsequently predict ballistic mass efficiency. The EBW results indicated that impact resistance of the bimodal microstructure was better than that of the equiaxed microstructure when the measured strength at HEL and spall strength were considered. It was also learned from the observation of fractured EBW specimens that fracture occurred by the initiation and propagation of long cracks in the equiaxed microstructure, whereas a number of microcracks were formed and connected each other in a zig-zag pattern to reduce the driving force for crack propagation in the bimodal microstructure. Since the EBW test helped experimentally estimate ultra-high-speed deformation and fracture behavior, it could be effectively used for the prediction of ballistic impact performance.
장순남,최준홍 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.10
The dynamic behavior of a tungsten heavy alloy (WHA) have been studied using an exploding bridgewire (EBW) detonator to load stress pulse onto the alloy plate. The particle velocity at the rear free surface of WHA was measured with varying the specimen thickness by a velocity interferometer system for any reflector (VISAR). Simple experimental technique has been introduced herein to obtain the Hugoniot elastic limit and spall strength of metals. The peak pressure generated by the EBW detonator has been exponentially decayed with increasing the sample thickness. The fracture behavior of WHA caused by the tensile stress pulse is similar to that due to the Charpy impact test.