• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.537-546
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• 2010

This research work contributed to a study for the procedure and methodology to assess the fatigue durability for a composite torque link of helicopter landing gear, which was newly developed and fabricated by the resin transfer moulding technique to interchange with metal component. The simulated load spectrum anticipated to be applied to the torque link during its operation life was generated using an advanced method of probabilistic random process, and the fatigue durability was evaluated by the strength degradation approach on the basis of material test data. The full scale fatigue test was also performed and compared with the analysis results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.156-162
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• 2008

The fatigue durability test using the actual size beam was performed with a cramp joint in order to apply to the highway bridge deck slab. Three types of beam were investigated for durability performance by considering stress conditions in real bridge deck slabs, 1) A beam with major shear force applied at the joint (RC Type) 2) A beam with major bending moments applied at the joint (PSC Type) 3) A beam with the pure shear applied at the joint. The experiment for beams with cramp joints showed that the cramp joint had enough durability for fatigue regardless of the overlaid length of the looped distribution bars under the current design strength level. Moreover, it was clarified that the enough durability for fatigue under the load repetition was achieved by increasing the joint span grater than 1.5D with the consideration of the deformation due to reduction in joint stiffness.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.103-115
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• 2013

Durability testing method trends of the thermal barrier coating(TBC) for the combustion chamber of the liquid-propellant rocket engine have been investigated. Many types of the durability testing method such as the mechanical tests to measure surface cohesion force, the thermal fatigue tests with laser, furnace, burner or plasma, the small scale combustion tests using injectors, and the thermo-mechanical fatigue tests were observed. The TBC with sufficient durability can be selected for the use of combustion chamber through such specimen-level tests and the durability can be verified by the tests using the real scale combustion chambers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.603-615
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• 2012

Durability testing method trends of the thermal barrier coating(TBC) for the combustion chamber of the liquid-propellant rocket engine has been investigated. Many types of the durability testing method such as the mechanical tests to measure surface cohesion force, the thermal fatigue tests with laser, furnace, burner or plasma, the small scale combustion tests using injectors, and the thermo-mechanical fatigue tests were observed. The TBC with sufficient durability can be selected for the use of combustion chamber through such specimen-level tests and the durability can be verified by the tests using the real scale combustion chambers.

• Journal of the KSME
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• v.55 no.2
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• pp.45-49
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• 2015

해석 및 측정 기술의 발전과 고내구성 소재 개발 등으로 인해 그동안 무한 수명으로 여겨져 왔던 천만 회의 피로수명을 넘어 운용되는 구조물들이 많아졌다. 이 글에서는 초고주기 피로현상과 이에 기초한 내구 설계의 개념 변화 및 시험법 등에 대해 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.747-752
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• 2013

Recently, virtual test laboratory techniques have been widely used to reduce vehicle development costs and time. In this study, a virtual durability test process using multibody dynamics simulation and fatigue simulation is proposed. The flexible multibody model of the front half of a car suspension is solved using road loads that are measured from durability test courses such as a Belgian road. To verify the simulation results, the measured loads of components and simulation results are collated.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.69-72
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• 2008

Bridge bearings are devices absorbing the displacements of the superstructure. Elastomeric bearings used generally as bridge bearings absorb the displacements of the superstructure using their rubber characteristics. Elastomeric bearings should make sure their shear fatigue performance not to impede the durability of bridge system. In this paper shear fatigue tests were performed and stiffness were measured through the shear fatigue tests. Tests results show the measured stiffness of elastomeric bearings have no specific tendency. This paper found that elastomeric bearings show bad shear performance or fail early if elastomeric bearings are manufactured with a doublefold elastomeric layer.

• Journal of the Korea Convergence Society
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• v.11 no.1
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• pp.169-174
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• 2020

Side bolster is a part of the vehicle seat that holds the passenger's body from the side to make it more stable when the passenger is seated in the seat. In this study, the structural and fatigue analyses of the side bolsters at a car seat were carried out with two models of A and B. The heavily loaded parts, the damage by fatigue at driving a car and the difference of durability due to the structure were examined and the distributions of stress and deformation, and the fatigue lives were seen. Also, the strength and durability were examined. This study result is thought to be devoted to decrease the fatigue damage and increase the fatigue life and durability according to the design of bolster. This result is able to improve the product by applying the design of automotive side bolster practically. And it is thought to be the advantage to apply this study result to the convergence research with esthetic sense.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.10-15
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• 2017

The refraction expansion joints have been newly developed by complementing the problems of shock, noise, replaceability, displacement in the direction perpendicular to bridge, vertical difference, which are problems of existing expansion joints. The Refraction expansion joints are characterized by continuous surfaces with small impact and low noise. The behavior of the Refraction expansion joints performs the bridge expansion behavior by rotation of the link. In the rotational behavior of the link, the bolt is the central axis of the behavior. Therefore, it can be said that the durability of the bolt is very important. However, the theoretical and experimental verification of the bolt durability of the Refraction expansion joint is lacking. In this paper, to verify the fatigue durability of the bolt, test specimens with a 300 mm Refraction expansion joint were fabricated. A strain gauge dedicated to the bolt was installed inside the manufactured test specimen bolt. The test method was applied in accordance with KS F 4425. The fatigue durability of the bolts assembled inside the diaphragm expansion joint was confirmed by the repeated fatigue test of 2,000,000 cycles.

• Composites Research
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• v.23 no.6
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• pp.26-31
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• 2010

This research work contributes to a study for the procedure and methodology to assess the fatigue durability for a composite torque link for helicopter landing gear, which was newly developed and fabricated by the resin transfer moulding technique to interchange with metal component. The simulated load spectrum anticipated to be applied to the torque link during its operation life was generated using an advanced method of probabilistic random process, and the fatigue durability was evaluated by the residual strength degradation approach on the basis of material test data. The full scale fatigue test was performed and compared with the analysis results.