• International Journal of Naval Architecture and Ocean Engineering
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• 제3권2호
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• pp.116-121
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• 2011

The Spectral Fatigue Analysis is representative fatigue life assessment method for vessels. This Analysis is performed generally for the whole vessel and many assessment sites. The spectral fatigue analysis is performed through the process of hydrodynamic response analysis, global structural analysis, local structural analysis and calculation of fatigue damage. In these processes, fatigue damage is affected by many variables. The representative variables are S-N curve data, wave scatter data, wave spectrum, bandwidth effect and etc. In this paper, the effects of these variables to the fatigue damage are analyzed through the spectral fatigue analysis for 170k LNGC.

• 대한조선학회 특별논문집
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• 대한조선학회 2017년도 특별논문집
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• pp.80-87
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• 2017

This paper is related to structural assessment considering the hydroelastic response of ultra large container ships, especially from whipping (bow or stern impacts) and from springing (resonance). In general, whipping contributes both to increased fatigue and extreme loading, while springing does mainly contribute to increased fatigue loading. To evaluate the hydroelastic response quantitatively with high accuracy, numerical code considering hydro-structure coupling was applied and fatigue strength of a 13,100 TEU class containership was verified. The segmented model test and full scale measurement were also needed to assess the effect of whipping and springing on the fatigue and extreme capacity in more realistic way and for verification of the numerical tools. With reference to class rule, fatigue assessment considering springing effect and extreme assessment considering whipping effect were introduced.

• 자동차안전학회지
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• 제12권3호
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• pp.27-33
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• 2020

In this paper, the process of predicting efficient durability performance for vibration durability test of automobile parts using vibration test load on automobile fuel tank is presented. First of all, the common standard load that can be applied to the initial development process of the automobile was used for the fuel tank and the vulnerability of the fuel tank to the vibration fatigue load was identified through frequency response analysis. In addition, the vulnerability of the fuel tank was re-enacted through vibration durability test results, and the scale factor was applied to the standard load. In order to predict the vibration durability performance required for detailed design, vibration fatigue analysis was performed on the developed vehicle with the frequency of vibration severity equivalent to the durability test, and the vulnerability and life span of the fuel tank were identified through the process of applying weights to these selected standard loads, thereby reducing the test time of the development vehicle.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1187-1192
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• 2008

In this paper, a versatile multi-objective optimization concept for fatigue life prediction is introduced. Multi-objective decision making in engineering design refers to obtaining a preferred optimal solution in the context of conflicting design objectives. Compromise decision support problems are used to model engineering decisions involving multiple trade-offs. These methods typically rely on a summation of weighted attributes to accomplish trade-offs among competing objectives. This paper gives an interpretation of the decision parameters as governing both the relative importance of the attributes and the degree of compensation between them. The approach utilizes a response surface model, the compromise decision support problem, which is a multi-objective formulation based on goal programming. Examples illustrate the concepts and demonstrate their applicability.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.336-341
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• 2003

In this paper, resonance durability analysis technique is presented for the fatigue life assessment considering dynamic effect of a vehicle system. In the resonance durability analysis, the frequency response and the dynamic load on frequency domain are used. Multi-body dynamic analysis, finite element analysis, and fatigue life prediction method are applied for the virtual durability assessment. To obtain the frequency response and the dynamic load, the computer simulations running over typical pothole and Belgian road are carried out by utilizing vehicle dynamic model. The durability estimations on the rear suspension system of the passenger car are performed by using the presented technique and compared with the quasi-static durability analysis. The study shows that the fatigue life considering resonant frequency of vehicle system can be effectively estimated in early design stage.

• Earthquakes and Structures
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• 제11권4호
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• pp.649-664
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• 2016

A seismic damaged bridge may be hit again by a strong aftershock or another earthquake in a short interval before the repair work has been done. However, discussions about the impact of the unrepaired damages on the residual earthquake resistance of a steel bridge are very scarce at present. In this paper, nonlinear time-history analysis of a steel arch bridge was performed using multi-scale hybrid model. Two strong historical records of main shock-aftershock sequences were taken as the input ground motions during the dynamic analysis. The strain response, local deformation and the accumulation of plasticity of the bridge with and without unrepaired seismic damage were compared. Moreover, the effect of earthquake sequence on crack initiation caused by low-cycle fatigue of the steel bridge was investigated. The results show that seismic damage has little impact on the overall structural displacement response during the aftershock. The residual local deformation, strain response and the cumulative equivalent plastic strain are affected to some extent by the unrepaired damage. Low-cycle fatigue of the steel arch bridge is not induced by the earthquake sequences. Damage indexes of low-cycle fatigue predicted based on different theories are not exactly the same.

• 한국철도학회논문집
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• 제10권5호
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• pp.499-505
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• 2007

본 연구의 주목적은 고속선 콘크리트 슬래브 궤도시스템에서 레일패드의 피로효과에 따른 영향을 분석하는 데에 있다. 이에 3차원 해석모델 및 실내시험을 통해 도출된 레일패드의 피로효과(경화, 스프링계수 증가)가 고속선 궤도의 역학적 거동에 미치는 영향을 분석하였다. 본 연구에서는 콘크리트 슬래브 궤도의 적정 탄성력 확보여부를 의미하는 레일패드의 적정스프링계수 산정에 관한 연구의 일환으로 고속철도 콘크리트 슬래브 궤도에 적용된 레일체결시스템에 대한 실내시험을 통한 레일패드의 정적스프링계수를 산정하고 체결시스템에 대한 피로시험을 통해 도출된 피로효과가 고려된 레일패드의 스프링계수 변화를 해석모델에 적용함으로써 향후 고속선 콘크리트 슬래브 궤도운영에서의 열차 주행안정성 확보 및 합리적인 궤도유지관리를 위한 기초데이터를 확보하고자 한다.

• 한국음향학회지
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• 제28권7호
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• pp.646-652
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• 2009

본 논문에서는 점용접 너깃의 피로수명을 고려한 차량 서브프레임의 용접간격 최적화 설계기법이 제안된다. 주파수영역 피로해석기법에 의해 점용접 너깃의 피로수명이 평가된다. 피로해석에서 사용되는 입력 데이터는 벨지안로 프로파일을 통과하는 차량동역학 해석과 차량 서브프레임 유한요소모델의 모드 주파수 해석을 통해 얻는다. 주파수 영역 피로해석으로 부터 얻은 피로수명 결과로부터 용접간격 최적화를 수행 할 설계점들이 선정된다. 점용접 너깃의 피로수명을 최대화시키는 용접간격을 얻기 위하여 4-요인, 3-수준 직교배열 실험계획법이 사용된다. 본 연구를 통하여 최적화된 서브프레임은 초기모델에 비하여 최소 피로수명을 갖는 용접 너깃의 피로수명이 약 65.8 % 증대되는 것을 알 수 있다.

• Steel and Composite Structures
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• 제46권6호
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• pp.745-757
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• 2023

In order to study the fatigue performance of the flat steel plate-lightweight aggregate concrete hollow composite bridge slab subjected to fatigue load, both static test on two specimens and fatigue test on six specimens were conducted. The effects of the arrangement of the steel pipes, the amplitude of the fatigue load and the upper limit as well as lower limit of fatigue load on failure performance were investigated. Besides, for specimens in fatigue test, strains of the concrete, residual deflection, bending stiffness, residual bearing capacity and dynamic response were analyzed. Test results showed that the specimens failed in the fracture of the bottom flat steel plate regardless of the arrangement of the steel pipes. Moreover, the fatigue loading cycles of composite slab were mainly controlled by the amplitude of the fatigue load, but the influences of upper limit and lower limit of fatigue load on fatigue life was slight. The fatigue life of the composite bridge slabs can be determined by the fatigue strength of bottom flat steel plate, which can be calculated by the method of allowable stress amplitude in steel structure design code.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.29-35
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• 2014

This paper aims to obtain the effect of lightweight on Radius rod. The response surface method used in the paper is the statistical method. Optimization method is performed with the Radius rod using the lightweight material. Structural analysis is executed by using the ANSYS program to find static and dynamic responses. From this study result, it is verified that the response surface method has the advantage of optimum value in comparison with other optimization methods. The analysis is also performed by response surface method to derive optimal design values. Steel model and aluminium initial model are obtained by finite element analysis to clarify design criteria and the results are compared with three models each other. The weights can be reduced by optimal design analysis results of these models similar to those of existing products. The quantitative goals in this study can also attained through results of fatigue analyses. The reliability on optimal design of Radius rod can be improved by use of structural and fatigue analysis results.