• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.343-349
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• 2015

This is a study for the improvement of the fractured lug structure that connects the landing gear to the fuselage of the aircraft using the composite leaf spring landing gear. The lug surface was analyzed to find out the cause of fracture. The lug was destroyed by the crack initiation and propagation under the repeated stresses. The frictional wears of the lug structure were proceeded and that affected adversely to the crack. Also, the square protrusion of the lug has a weak shape to bring about stress concentration. The design changes were conducted and the test was performed to verify changed design results.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.70-75
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• 2018

The mounted store on an aircraft shall be subjected to an ground separation test to verify that a safe separation has been made before it is actually installed to the aircraft. In this study, ground ejection test was conducted with dummy missile to verify the stability of the drop on the land. Bomb rack unit essential to testing ground ejection test, operate at high pressure and produce a significant ejection force to push the missile away from any large orifice. Bomb rack unit modified their bombe pressure and orifice diameter to photograph the drop movement of dummy missile with high-speed camera and to analyze their drop displacement and speed. It is considered useful to provide the initial data for the ejection force analysis on aircraft with actual flight and to carry out the ground separation tests of aircraft with future developments.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.6
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• pp.675-680
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• 2016

This is a study for the improvement of the defected elevator spar in operating aircraft. The elevator spar web holes were analyzed to find out the cause of the cracks. The fatigue striations were observed and the cracks occurred by the repetitive stresses during the elevator works. Also the outboard connection structure of the elevator and horizontal stabilizer was more weak shape than the inboard. The design changes were recommended and the analyses were performed to verify the improvement of the changed shapes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1107-1114
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• 2011

In this paper, the fatigue life of a laser peened structure was predicted. In order to calculate residual stress induced by laser peening finite element simulation was carried out. Modified Goodman equation was used to consider the effect of compressive residual stress induced by laser peening in fatigue analysis. In addition, additive adjustment factor approach was applied to consider S-N curve model uncertainty. Consequently, the reliable bounds of the predicted fatigue life of the laser peened structure was determined.