• Composites Research
• /
• v.27 no.4
• /
• pp.130-134
• /
• 2014

The purpose of this paper is to build DB in order to Propose new constitutive equations by redefining constitutive equations for Polyurethane presented by Jeong et al. [12] based on Quasi-static test and Impact test DB of Expanded polypropylene using cylindrical specimens with 4 different densities presentsd by Kim et al. [7] for EPP foam and combining the impulse-momentum theory.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.3
• /
• pp.139-144
• /
• 2004

Dynamic crack initiation in ductile steel is investigated by means of impact loaded 3 point bend(PB) specimens. Results from non-viscoplastic and viscoplastic materials are compared. Their materials are applied with various impact velocities and static strain rates. The specimen has the size 320${\times}$750 mm with a thickness of 10 mm. A modified 3PB specimen design with reduced width at the ends has been developed in order to avoid the initial compressive load of the crack tip and also to avoid the uncertain boundary conditions at the impact heads. Numerical simulations are made by using the FEM code ABAQUS. Therefore, their results are plotted by shapes of the von Mises plastic stress and equivalent plastic strain of the specimens applied by various impact velocities.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.267-270
• /
• 2007

Korea Aerospace Research Institute(KARI) made a scramjet engine test contract with the University of Queensland in October 2006. The experiments were conducted at Mach 7.6, Altitude 31.2 km condition in the T4 free piston-driven shock tunnel in June 2007. In this paper, the short introduction and data processing technique of the T4 free piston-driven shock tunnel will be explained.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.6 no.1
• /
• pp.30-38
• /
• 2002

Bullet impact tests for two solid rocket motors were performed and its results were compared and analyzed. One was loaded with the existing propellant with decreased weight content of burning rate catalyst and added high density additives to improve mechanical properties and the other was loaded with the existing propellant with decreased weight content of burning rate catalyst to improve its insensitivity as well as to maintain the ballistic performance. The composite cases were used for both motors.

• Proceeding of EDISON Challenge
• /
• 2016.11a
• /
• pp.74-77
• /
• 2016

본 연구에서는 Scream Jet Intake에 발생하는 충격파 경계층에서 속도를 Supersonic에서 Subsonic으로 줄였을 때의 상호작용을 EDISON_CFD로 해석하기로 한다. 이상적인 공기 유동에서 충격파 경계층의 각도를 $15^{\circ}{\sim}20^{\circ}$, $25^{\circ}{\sim}30^{\circ}$, $15^{\circ}{\sim}40^{\circ}$, $25^{\circ}{\sim}50^{\circ}$와 같이 두 개($5^{\circ}$, $25^{\circ}$)의 각도 차이를 두어 이중압축램프에서의 유동현상을 EDISON_CFD로 수행하고 분석하였다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.3 no.5
• /
• pp.38-46
• /
• 1995

In this paper, an experimental study on the effects of the impact damage and the perforation characteristic of CFRP laminates with different fiber stacking orientation and ply number was done through an observation of interrelations between the impact energy vs. transmitted energy and the impact energy vs. absorbed energy per unit volume. The velocities of the ball before or after impact are measured by the high-speed camera. And when CFRP laminates are subjected to tranverse impact by a steel ball(${\phi}10$), the delamination shapes generated by impact damage are observed by using SAM (Scanning acoustic Microscope).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.7
• /
• pp.947-952
• /
• 2010

Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions prescribed in ISO and SAE standards. The impulse pressure test machine needs to have a high pressure, a precise control system and a long life. It should satisfy the requirements for fabrication of the impulse tester to generate ultra high pressure in the hydraulic system. In the impulse tester, a servo-valve control system is adopted; although the control application is convenient, it is expensive owing to the cost of developing the system. The type of the control system determines the pressure wave, which affects the components that are tested. In this study, the manufacturing process and the intensifier system design related to the flow, pressure, and the increasing rate of pressure are investigated. The results indicate the ultra high pressure waves in the system.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2009.10a
• /
• pp.198-202
• /
• 2009

Split Hopkinson pressure bar(SHPB) is used to obtain compressive stress-strain data and deformation characteristics of brittle materials such as rock and concrete. SHPB demands both dynamic stress equilibrium condition and nearly constant strain rate before the failure of the specimen. Pulse shape technique, which places a thin metal disk between launched impact bar and incident bar, should be adopted to satisfy both conditions. In this study, metallic disks with various shapes were used to control the incident impact wave. The results show that the peak value of stress and the length of waves increased with decreasing thickness and diameter of the pulse shaper. In order to investigate shape and strain rate-dependency of the pulse shapers, dynamic compressive stress-strain curves were obtained and analyzed.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.23 no.1
• /
• pp.45-52
• /
• 2010

This paper estimated the impact factor using the finite element program to confirm the dynamic behavior of new type of bridges constructed by introduction of new vehicles and compared the design criteria about the impact factor applied to domestic as well as each country. The study estimated effects of the impact factor according to pipe truss types modeled as respectively 34m, 44m, 54m and span length. The vehicle models are vehicle for bimodal tram of two axis and three axis which passes on actual bridge and dump truck model proposed by Park Young suk(1997). Each vehicle is estimated the impact factor according to velocity from 10 to 100(km/h) and examined. Also, the study investigated and compared the design regulation of domestic and a foreign country based on the impact factor on span center calculated in accordance with vehicle and span length.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.18 no.5
• /
• pp.43-53
• /
• 2014

Shock tunnels are known to be capable of simulating flow-field environments of supersonic and hypersonic flights. They have been operated successfully world-wide for almost half a century. As a consequence of the strong interest in hypersonic vehicles in Korea, attention has been given on this type of facility and so an intermediate-sized shock tunnel has lately been built at KAIST. In the light of this, this paper presents our tunnel performance and some of the model scramjet test data. The freestream flow used in this work replicates a supersonic combustor environment for a Mach 5.7 flight speed.