• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.64-71
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• 2024

The external fuel tank of an aircraft is a main component that can increase the cruising range of the aircraft. It must be able to be stably separated from the pylon in an emergency situation. At this time, a separation load is applied to the fin and the pivot of the external fuel tank. To stably separate the external fuel tank, the structural soundness of the fin and the pivot must be confirmed. In this study, structural tests were conducted to verify the structural integrity of the external fuel tank pin and pivot when the external fuel tank was separated from the aircraft. Results are then presented. In this paper, a test configuration diagram consisting of the hydraulic and load control equipment, data acquisition system, and pneumatic supply unit used in the structural test was explained. Test installation and test load application plan for each test condition were provided. As results of the structural test, it was found that test load and internal pressure of the test specimen were properly controlled within the allowable range in each test. It was confirmed that serious structural defects in the test specimen did not occur under required load conditions. In conclusion, through structural test for design limit load and design ultimate load, it was proven that the fin and pivot of the external fuel tank for aircraft covered in this study had sufficient structural strength.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.111-118
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• 2007

KSLV-I which is being developed in KARI is composed with two stages, and adaptor ring is used for coupling stage. Cables for interconnecting between stage is exposed on the outside. Also 8 pyro bolts which are installed in adaptor ring are used for separation of stage. In general, cowl is used for protecting exposed parts or structure which are anxious about damage from outer environment. In KSLV-I, two kind of cowls are designed. The one is umbilical cowl, and the other is pyro bolt cowl. Because cowl is exposed on the outside, heat and pressure load developed from air have effect on cowls. Therefore verification of structural strength through static analysis is required. In this study, static analysis in load condition except heat load is accomplished. In result of analysis, structural strength of pyro bolt cowl is verified. But breakage of umbilical cowl is confirmed in pressure load condition. So design of umbilical cowl is modified for satisfying required structural strength. And structural strength of umbilical cowl through analysis is verified.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.509-512
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• 2009

본 논문에서는 KBC(Korean Building Code)와 IBC(International Building Code)의 풍하중 기준의 비교 분석을 통하여, BIM 프로세스 기반의 구조해석 및 설계 프로그램에서 풍하중 산정 시 국내 건축구조설계기준(KBC)을 적용하기 위한 방안을 제시하는 것을 목적으로 한다. 현재 BIM 기반 구조해석 및 설계 프로그램 중에는 한국구조설계기준(KBC)에 부합하는 풍하중 산정이 가능한 프로그램이 존재하지 않는다. 구조설계 기준에서 특히 풍하중 산정 방법은 기준 및 지역에 따른 산정 방법에 차이가 있기 때문에, 구조설계의 안전성을 높이고 한국 실정에 맞는 건축물의 설계를 위해서 KBC 기준의 적용이 필요하다. 본 연구에서는 IBC와 KBC 내의 풍하중 산정 방법의 차이점을 비교 분석하고, 실제 사례연구를 통하여 풍하중 산정의 차이를 확인한다. KBC 기준 풍하중 산정 결과를 구조해석 및 설계 프로그램에 적용하기 위한 방법으로써 외부 프로그램을 활용하며 외부 프로그램에서 산정한 풍하중을 다시 구조해석 및 설계 프로그램 상에 입력하여 구조해석을 수행함으로써 KBC 기준 풍하중의 적용을 통한 한국형 BIM 구조해석 및 설계의 방안을 제시한다.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.337-345
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• 2009

The purpose of this study is to investigate the shear strengthening effectiveness of the beams strengthened with near surface mounted (NSM) and external bonded (EB) CFRP strips. A total of nine concrete beams were made and tested. From this study, it was found that the shear stiffness and strength of the beams strengthened with NSM and EB strips were significantly improved compared to the control beam. Failure of the beam strengthened with NSM and EB strips was initiated by shear cracks, propagated diagonally to the adjacent epoxy grooves without crossing the epoxy and finally sudden diagonal crack connecting the point of application of load and flexural crack was occurred. For the beam strengthened combined with NSM and EB CFRP strips, the tensile strains in the NSM CFRP strips were observed in the range of 0.35% to 0.45% and strains with EB strips were measured about 0.3%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.96-96
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• 2004

고성능 섬유강화 복합재는 비강성과 비강도가 높고 내부식성과 피로특성이 우수하지만 외부에서 가해지는 하중에 의해 수지, 강화섬유와 수지와의 경계면, 적층 경계면 등에 육안으로 식별하기 어려운 손상이 유발될 가능성이 있으며 이로 인해 구조재로서의 역할을 하지 못하는 경우가 발생한다. 최근에는 외부하중으로 인해 복합재 구조재에 손상이 발생한 경우 자가치료제가 저장된 마이크로캡슐을 이용하여 손상을 보수하려는 시도가 행해지고 있다.(중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.222-229
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• 2022

The extensive use of external prestressing system with PSC-I beam to strengthen reinforced and prestressed concrete members requires the full understanding of the behavior of the strengthened members. The main approach of this research was to experimentally investigate the flexural performance of the PSC-I beam considering external tendon and an equation was developed which indicated the produced incremental stress in the tendon due to applied load. Further, this equation was verified through performing static loading tests on two experimental specimens considering the presence or absence of external tendon. The test results revealed that, the flexural performance enhanced due to the use of external tendon. Moreover, the magnitude of the estimated flexural strength using proposed stress increasing equation almost coincides with the experimental test results. However, it was the evident of the improvement of the flexural performance of the system by reinforcing with the external tendon and also proved that the proposed equation was valid and effective.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.605-611
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• 2019

The fuel sloshing due to the rapid manoeuvre of the aircraft causes significant loads on internal components, which may break components or piping. In particular, a significant load is applied to the joint of the external fuel tank by sloshing movement, which may affect the safety of the aircraft when the joint of the external fuel tank is damaged. Therefore, in order to improve the survivability of aircraft and crew members, the design of external fuel tanks, and joints should be performed after evaluating the sloshing load through a numerical analysis of the fuel sloshing conditions. In this paper, a numerical analysis was performed on the sloshing test of the external fuel tank for rotorcraft. ALE (Arbitrary Lagrangian Eulerian) technique was used, and the test conditions specified in the U.S. Military Specification (MIL-DTL-27422D) was applied as the conditions for numerical analysis. As a result of the numerical analysis, the load on the joint of the external fuel tank was calculated. Moreover, the effects of sloshing movement on structural soundness were assessed through analysis of stress levels and margin of safety on metal fittings and composite containers.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.450-453
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• 2009

본 논문에서는 지진하중을 고려하여 충분한 연성거동이 가능하도록 배근한 철근콘크리트 횡하중 저항 골조(내진상세)와 고정하중과 적재하중만을 고려하여 설계한 중력하중 저항 골조(일반상세)를 대상으로 외부기둥과 내부기둥에 연결된 보의 연쇄붕괴 거동을 평가하기 위한 실험을 수행하였다. 일방향 가력실험 결과에 따르면 내진상세의 경우 대변형 상태에서 보의 하단철근의 파단이후 상단 압축철근이 인장력을 부담하면서 전체 보 부재는 축인장력이 작용을 하면서 힘-변위 곡선은 상승하는 현수작용이 발현되었다. 그러나 일반상세의 경우 충분한 현수작용이 발현되기 전에 보의 주근이 정착된 외부기둥 접합부의 파괴로 인하여 저항내력이 감소하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.565-572
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• 2009

This work intends to establish the reliability and fracture toughness $K_{IC}$ criterion of welded joints by EGW for high strength EH36-TMCP ultra thick plate. For this, firstly thermo elasto-plastic analysis has been carried out on two pass X-groove butt joint model to clarify the thermal and mechanical behaviour(residual stress, plastic strain, magnitude of stress and their distribution and production mechanism). Moreover, to establish fracture criterion, analysis of fracture toughness $K_{IC}$ has been performed under the notch machined and residual stress with the load condition on EGW welded joints. A quantitative fracture criterion for EGW welded joints is suggested by using $K_{IC}$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.271-281
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• 2005

The effects of radiation damping is used to compensate the truncated boundary which is relatively close to the structure-fluid interface in the fluid element surrounding the submerged structures. An efficient ring element is presented to model the shell and fluid element which fully utilizes the characteristics of the axisymmetry. The computational model uses the technique which separate the meridional shape and circumferential wave mode and gets similar result with the exact solution in the eigenvalues and the earthquake analysis. The fluid-structure interaction techniques is developed in the finite element analysis of two dimensional problems using the relations between pressure, nodal unknown acceleration and added mass assuming the fluid to be invicid, incompressible and irrotational. The effectiveness and efficiency of the technique is demonstrated by analyzing the free vibration and seismic analysis using the added mass matrix considering the structural deformation effect.