• 한국생산제조학회지
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• 제21권3호
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• pp.451-458
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• 2012

This study aims at the structural analysis with fatigue according to the configuration of railway vehicle wheel. Maximum equivalent stress or deformation is shown at the lower face in contact with wheel and rail. As model B has the maximum stress or deformation which becomes lower than model A, model B is shown to have more durability than model A. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^{11}$ Pa and the amplitude stress of 0 to $10^{10}$ Pa, the possibility of maximum damage becomes 3%. This stress state can be shown with 6 times more than the damage possibility of 'SAE Bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of railway vehicle wheel by prevention and durability against its damage.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.148-155
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• 2011

This study analyzes stress, fatigue and vibration at clutch on the rotation of wheel. Eigenfrequencies from 1'st to 6'th order about clutch assembly are shown with the vibration at more than 800Hz. Maximum equivalent stress is shown with the frequency of 800Hz in case of the harmonic vibration applied with force. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample History' with the average stress of 0MPa to $-10^5$ MPa and the amplitude stress of 0MPa to $10^5$ MPa, the possibility of maximum damage becomes 3.23%. This stress state can be shown with 6 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the safe design of clutch.

• 대한조선학회논문집
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• 제28권2호
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• pp.228-240
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• 1991

균열진전에 관한 많은 실험결과는 피로 균열진전 과정이 확률과정(stochastic process)임을 보여주고 있다. 따라서, 피로 균열진전에 관한 연구는 확률론적 기반에서 다루어져야 한다. 본 연구에서는 균열의 진전과정을 discrete Markov process로 가정하여, Bogdanoff가 제안한 Markov chain model(MCM)을 이용하여 구조물의 신뢰도를 평가할 수 있는 방법을 제시한다. 본 연구에서는 구조부재의 파괴형태로 누출, 소성붕괴 그리고 취성파괴를 취하였으며, 초기 균열크기의 변동성, 검사의 효과 등이 고려되었다. 또한, 불규칙 하중은 등가음력의 개념을 도입하여 처리하였다. 그리고, 구조물에의 계산례를 통하여 본 연구의 유용성을 보였다.

• 한국산학기술학회논문지
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• 제13권7호
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• pp.2865-2871
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• 2012

본 논문에서는 접착제로 접합된 DCB(이중외팔보) 시험편의 피로 해석을 수행하였다. 두께가 25 mm 및 40 mm인 두 모델들의 피로수명과 피로손상의 해석 결과를 비교해보면, 두께 25 mm인 모델이 두께 40 mm인 모델에 비하여 수명과 손상이 불리한 것으로 나타났으며 불규칙 피로하중에서는 'SAE transmission'에서 가장 불리한 값을 나타냈다. Rainflow matrices에서는 'SAE bracket history'에서 가장 취약한 것으로 나타났다. Damage matrices에서는 상대적으로 두께 25 mm인 모델이 불리한 모습을 보였지만, 상대적인 손상 가능성에서는 두께 40 mm인 모델이 더 높은 것으로 나타났다. 또한 'SAE transmission'에서 가장 안정한 경향을 보이고 있고 상대적인 손상으로서 약 1.1 에서 1.8% 정도로 가장 작은 것으로 나타났다. 본 연구에서 얻어진 해석 결과를 접착제로 접합된 실제 복합재 구조물에 적용시켜 파괴거동을 분석하고 그 기계적인 특성을 파악할 수 있다.

• 한국소음진동공학회논문집
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• 제21권9호
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• pp.798-804
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• 2011

In this paper, optimal spot weld layout design for a shock tower structure is presented. This design increases the fatigue life of the spot-welds thereby increasing the fatigue life of the shock tower itself. In order to predict the fatigue life, a quasi-static analysis has been conducted then a fatigue analysis was performed through the application of random vibration loads. In order to optimize the spot weld layout, the design variables that have an effect on the spot weld fatigue life were determined. A spot weld fatigue analysis was then conducted based on the experiment design. Finally, a response surface model was made using the fatigue analysis results and an optimized spot weld layout model, one that increases the fatigue life of the spot welds and thereby the fatigue life of the shock tower, was developed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.166-169
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• 2004

A fatigue test was used to evaluate the fatigue life of an actual structure. The loaded state and the constraint condition of an actual structure must be same as the specimen in order to apply the test results to an actual structure by the specimen. The loaded state and constraint conditions can't be same as the specimen in the actual structure which is complicated. In order to reduce these differences, an actual structure test with a lot of frequencies is need to get a fatigue life curve. Therefore, ten sets of accelerated test units which attached unbalanced mass were composed in this study. Acceleration history about the vibration of an actual structure was acquired. Rainflow counting was used on acceleration history, and the life curve return formula was assumed. The return formula that damage satisfied `1' was acquired in a feedback process by the Miner's rule, which was the linear cumulative damage theory. A conservative fatigue life curve was determined with a return formula to have been presumed by each set. The fatigue life of regular rpm condition was calculated by these conservative fatigue life curves.

• 한국기계가공학회지
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• 제11권5호
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• pp.68-75
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• 2012

This study aims at the structural analysis of vibration and fatigue according to the tie rod configuration. The maximum displacement amplitude is happened at 156Hz by harmonic vibration analysis, this tie rod model can be broken as the weakest state. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sine wave' becomes most stable. In case of 'Sine wave' with the average stress of 0MPa and the amplitude stress of 570MPa, the possibility of maximum damage becomes 70%. This stress state can be shown with 140 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design on tie rod by investigating prevention and durability against its damage.