• Journal of Magnetics
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• 제18권2호
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• pp.90-94
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• 2013

We designed a model composed of a ring type magnet, a yoke, and a sensing coil embedded in a projectile for simulating the muzzle velocity. The muzzle velocity was obtained from the master curve for the induced voltage at sensing coil and the velocity as the projectile pass through the magnetic field. The induced voltage and the projectile's velocity are fitted by the $2^{nd}$ order polynomial. The skin effect difference between projectiles which consist of aluminum-aluminum and aluminum-steel was small. The projectile will surely be burst at the pre-determined target area using the flight time and the projectile muzzle velocity calculated from the voltage induced at the sensing coil on the projectile.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.865-868
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• 2002

This study investigated the shape deformation of ball projectile(5.56mn) under the low energy impact by the use of the drop weight impact tester. ball projectile(5.56mm) consisted of the copper face with a lead core. The impact conditions were changed with the variations of the mass and the drop height of the impact tup. Shape deformation of ball projectile(5.56mm) after low velocity impact was measured using a video microscope and CCD camera. The test result showed that impact energy by changing of drop height of the impact tup affected shape deformation of ball projectile(5.56mm). So, it is important to study the relativity between shape deformation of ball projectile(5.56mm) and ballistic protection of plate(such as hybrid composite laminates) under the high velocity impact.

• 한국군사과학기술학회지
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• 제18권2호
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• pp.154-159
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• 2015

This paper deals with the effect of concrete target size on penetration of projectiles. We investigated the penetration depth and residual velocity of projectiles using the 2-D axial symmetric model. Most analysis were conducted with 13 kg projectile (striking velocity: 456.4 m/s) and concrete target with compressive strength of 39 MPa. This paper provided penetration depth (or residual velocity) versus ratio D/d (target diameter, D and projectile diameter, d). When the bottom of concrete cylinder was constrained, penetration depth converged to limit depth more than the ratio D/d of 36. The residual velocity of projectile with thin concrete target were investigated. The residual velocity was converged to specific velocity more than the ratio D/d of 16.

• Computers and Concrete
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• 제5권6호
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• pp.509-524
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• 2008

Containment structures not only are leak-tight barriers, but also may be subjected to impacts caused by tornado-generated projectiles, aircraft crashes or the fragments of missile warhead. This paper presents the results of an experimental study of the impact resistance of steel fiber-reinforced concrete against 45 g projectiles at velocity around 2500 m/s. An explosively formed projectile (EFP) was designed to generate an equivalent missile fragment. The formation and velocity of EFP are measured by flash x-ray. A switch made of double-layered thin copper sheets controlled the exposure time of each flash x-ray. The influence of the fiber volume fraction on the crater diameter of concrete slab and the residual velocity of the projectile were studied. The residual velocity of the projectile decreased as the fiber volume fractions increased. In this work, the residual velocity of the projectile was to 44% that of plain concrete when the fiber volume fraction exceeded 1.5%. Based on the present finding, steel fiber reinforced concrete with the fiber volume fraction exceeding 1.5% appear to be more efficient in protection against high velocity fragment impact.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.117-119
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• 1994

While the projectile in the induction type coil guns is in motion, there exists an induced current in the sleeve coils of the projectile. The motion includes not only the z-axial movement but transversal movement. The projectile in coil guns, which is not supported physically, gets a force in the transversal axis to have a motion in this axis. As a result of this motion, sleeve effects are exhibited to the projectile. This paper presents the analysis of the secondary effect especially due to the propelling velocity of the projectile.

• 한국분무공학회지
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• 제17권2호
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• pp.86-93
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• 2012

The effects of projectile impact system on the transient spray characteristic which is supersonic liquid tip velocity were studied by experimentally. Supersonic liquid jets were generated by impact of a high speed projectile driven by a Two-stage light gas gun. A high speed camera and schlieren optical system were used to capture the spray structures of the supersonic liquid jets. In a case of nozzle assembly Type-A, expansion gases accelerate a projectile which has a mass of 6 grams from 250 m/s at the exit of the launch tube. Accelerated projectile collides with the liquid storage part, then supersonic liquid jets are injected with instantaneous spray tip velocity from 617.78 m/s to 982.54 m/s with various nozzle L/d. However, In a case of nozzle assembly Type-B which has a heavier projectile (60 grams) and lower impact velocity (182 m/s), an impact pressure was decreased. Thus the liquid jet injected at 210 m/s of the maximum velocity did not penetrate a shock wave and fast break-up was occurred. Pulsed injection of liquid column generated second shock wave and multiple shock wave.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.1019-1029
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• 2006

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics, creation of new materials, etc, since it can create an extremely high-pressure state in very short time. Of many different types of ballistic ranges developed to date, two-stage light gas gun is being employed most extensively. In the present study, a theoretical work has been made to develop a new type of ballistic range which can easily simulate a flying projectile. The present ballistic range consists of high-pressure tube, piston, pump tube, shock tube and launch tube. The effect of adding a shock tube in between the pump tube and launch tube is investigated. This improvement is identified as the reduction in pressures in the high pressure tube and pump tube while maintaining the projectile velocity. Equations of motions of piston and projectile are solved using Runge-Kutta methods. Dependence of projectile velocity on various design factors such as high pressure tube pressure, piston mass, projectile mass, area ratio of pump tube to launch tube and type of driver gas in the pump tube are also analyzed. Effect of various gas combinations is also investigated. Calculations show that projectile velocities of the order 8 km/sec could be achieved with the present ballistic range.

• 한국군사과학기술학회지
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• 제24권6호
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• pp.619-628
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• 2021

In order to compare numerical analyses made by Song and Kim needed for predicting gas and water filling with experimental results we conducted an experiment to recover a test projectile (43.7 kg with a 155 mm diameter) at a velocity of 775 m/s in a soft recovery system with a length of 179 m using pressurized gas and filled water. The soft recovery system consisting of a series of pressure tubes had a diaphragm, piston, and water plug for filling the pressurized gas and water. We installed a continuous wave Doppler radar system for velocity measurements of the test projectile travelling in the pressure tubes and pressure transducers for measuring the pressure in the soft recovery system. Continuous wave Doppler radar has the advantage of achieving real-time measurements of the velocity of a test projectile. The velocity-time curve of the test projectile, measured using the continuous wave Doppler radar, and the pressure profile were compared with the numerical analysis results. The experiment results show good agreement with the numerical analysis results based on the one-dimensional Euler equation with an HLL Riemann solver.

• 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.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.28-29
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• 2014

In this study, flexural strength by fiber reinforced for steel fiber and reinforced polyamide fiber concrete, and concrete fracture properties by improvement of flexural toughness and high-velocity projectile impact were evaluated. As a result, it was confirmed that flexural strength are improved by distribution of stress and suppress of cracks, and the back desquamation of concrete by high-velocity projectile impact is suppressed. In addition, It was observed that the spalling of rear is caused when tension stress is caused as shock wave by high-velocity projectile impact was transferred to the rear and tension stress is suppressed by fiber reinforcement.