• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.394-399
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• 2004

In order to secure the safety of power steering system, it is necessary to perform the strength and the fatigue analysis of pulley in this paper. The applied stress distribution of the pulley subject to combined loads condition was obtained using finite element analysis. Based on these results, the fatigue life of the pulley with the variation of the fatigue strength was evaluated using durability analysis simulator. The optimal hole size to improved the safety of the pulley was investigated using parametric study. Moreover, the predicted fatigue life cycle with the simulator was verified by experimental tests.

• 한국안전학회지
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• 제16권2호
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• pp.27-35
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• 2001

For the purpose of healing the degradation part, $CO_2$ laser beam was irradiated with different irradiation condition (porer, diameter, velocity and beam type) to find out optimum irradiation condition. The test series of hardness, residual stress measurement, and fatigue were carried out after the irradiation. Experimental results show that micro-hardness values on the surface of the irradiated specimens m approximately 2.5 times higher than those of un-irradiated ones. Fatigue tests show that the fatigue life was improved by the compressive residual stress after laser beam irradiation. However, some specimens with different conditions show the shorter fatigue life. It means that laser beam irradiation with optimum irradiation condition and optimum absorb energy, Q can improve the fatigue strength.

• 한국안전학회지
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• 제11권4호
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• pp.10-15
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• 1996

In studying the fatigue strength of fillet welded the section of pressure vessel pad, this study was to evaluate the effect of weld toe notch and to compare the results of numerical analysis with the results of fatigue experiments of fillet welded A5l6 grade 60 steel specimens. The fatigue life for the Bead welded specimen was about 1.4 times as much it as the 1Pad welded specimen. Also, The fatigue life for the 2Pad welded specimen was about 1.5 times as much it as the 1Pad welded specimen. In $da/dN-{\Delta}K$ curve, the fatigue crack growth rate for the 1Pad welded specimen appeared higher than that of the 2Pad welded specimen in the same initial region of ${\Delta}K$, had a similar Inclination In the stabled region.

• 한국안전학회지
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• 제8권2호
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• pp.51-57
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• 1993

This study was done by ultrasonic testing. The proves used in this study were 5Z10$\times$10A70. The useful fatigue life of structural components is determined by the sum of the elapsed load cycles required to initiate a fatigue crack and to propagate the crack from subcritical size to critical dimensions. Thus, to predict the service life of many steel structures and to establish safe inspection intervals, an understanding of the Fatigue Crack Initiation and Fatigue Crack Propagation behavior in the steel is required. In the present study, the Fatigue Crack Initiation Life in SPS 5A steel was investigated by testing specimens having widely varying notch acuities. The variation in the notch acuity covered the range from notch root raidus 0.5mm to 2.5mm, and Fatigue Crack Initiation Life data were obtained in that range.

• 한국안전학회지
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• 제34권5호
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• pp.7-14
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• 2019

The type III vessel, which is used to store high-pressure hydrogen gas, is made by wrapping the vessel's liner with carbon fiber composite materials for strength performance and lightening. The liner seals the internal gas and the composite resists the internal pressure. The properties of the fiber composite material depends on the angle and thickness of the fiber. Thus, engineers should consider these various design variables. However, it significantly increases the design cost due to the trial and error under designing based on experience or experiments. And, for aluminum liners, fatigue loads due to using and charging could give a huge impact on the performance of the structure. However, fatigue failure does not necessarily occur in the position under the highest load in use. Therefore, for hydrogen storage vessel, fatigue evaluation according to design patterns is essential because stress distribution varies depend on composite layer patterns. This study performed an optimization analysis and evaluated a high-pressure hydrogen storage vessel to minimize these trial and error and improve the reliability of the structure, while simultaneously conducting fatigue assessment of all patterns derived from the optimization analysis process. The results of this study are thought to be useful in the strength improvement and life design of composite reinforced high-pressure storage vessels.

• 한국안전학회지
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• 제29권3호
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• pp.136-142
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• 2014

Recently a new version of PRO-LOCA program was released. Using the program, failure probability of pipes can be evaluated considering fatigue and/or stress corrosion crack growth and the effects of various parameters on the integrity of pipes in nuclear power plants can be evaluated quantitatively. The analysis results can be used to establish an inspection plan and to examine the effects of important parameters in a maintenance plan. In this study, sensitivity analyses were performed using the program for several important parameters including sampling method, initial crack size, number of initial fabrication flaws, operation temperature, inspection interval, operation temperature and nominal applied bending stress. The effect of parameters on the leak and rupture probability of pipes was evaluated due to fatigue or stress corrosion crack growth.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2977-2981
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• 2021

Corrosion fatigue crack growth (FCG) behavior of 316LN stainless steel was investigated in high-temperature pressurized water at different temperatures, load ratios (R = K_max/K_min) and rise times (t_R). The environmental assisted effect on FCG rate was observed when both the R and t_R exceeded their critical values. The FCG rate showed a linear relation with stress intensity factor range (ΔK) in double logarithmic coordinate. The environmental assisted effect on FCG rate depended on the ΔK and quantitative relations were proposed. Possible mechanisms of environmental assisted FCG rate under different testing conditions are also discussed.

• 해양환경안전학회지
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• 제15권3호
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• pp.217-222
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• 2009

선박을 운항하는 항해사의 피로도(Fatigue)는 안전항해와 매우 밀접한 관계를 가지고 있다. 또한, 당직항해사의 피로는 중대한 해양사고를 초래할 수 있다. 본 연구에서는 항해사의 근무환경, 피로유발요인 및 피로증세 등에 대하여 문헌조사를 실시하였다. 그리고 실습항해사를 대상으로 졸음, 정신적 육체적 작업부하도에 대한 피로도 관련 설문조사를 실시하고 그 결과를 분석하였다. 마지막으로 이와 같은 피로도 조사 및 설문조사 분석결과를 바탕으로 항해사의 피로도 분석항목을 선정하고 이를 기반으로 향후 항해사의 업무수행능력을 평가하기 위한 피로도 분석모델을 제안하였다.

• 한국정밀공학회지
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• 제30권2호
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• pp.231-235
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• 2013

The purpose of this paper is to compare with estimation of equivalent fatigue load in time domain and frequency domain and estimate the fatigue life of structure with multi-axial vibration loading. The fatigue analysis with two methods is implemented with various signals like random, sinusoidal signals. Also an equivalent fatigue life estimated by rainflow cycle counting in time domain is compared with results estimated with probability density function of each signal in frequency domain. In case of frequency domain, equivalent fatigue life can estimate through Dirlik's method with probability density function. And the work proposed in this paper compared the fatigue damage accumulated under uni-axial loading to that induced by multi-axial loading. The comparison is preformed for a simple cantilever beam, which is exposed to vibrations of several directions. For verification of estimation performance of fatigue life, results are compared to those of FEM analysis (ANSYS).

• 해양환경안전학회지
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• 제14권1호
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• pp.77-82
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• 2008

최근 선박충돌사고 또는 좌초사고와 같은 중대한 해양사고를 조사할 때, 사고 관련자의 피로도(Fatigue)가 선박의 안전운항에 부정적인 영향을 미치는 인간과실(Human error) 유발요인으로 작용하여 항해사의 인지능력 및 업무수행능력을 저하시키는 중요한 요인으로 인식되고 있고, 이에 대한 많은 연구가 수행되고 있다. 본 연구에서는 국내 해양사고관련자에 대한 피로도를 체계적으로 조사 분석하기 위한 일환으로 미국연안경비대의 피로도 조사프로그램을 분석하여 국내 해양안전심판원 웹사이트에 조사프로그램을 구현하였으며, 그 결과를 고찰하여 효율적인 피로도조사가 수행 가능하도록 몇 가지 방안을 검토하였다.