• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.785-791
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• 2002

본 연구에서는 자동차의 안락성에 큰 영향을 미치는 운전자세와 운전에 따른 피로도를 평가하는 방법에 대해 다루고자 한다. 이러한 피로도를 평가하기 위해서 EMG, ECG와 같은 생리신호를 이용한 정량적인 평가방법과 졸림감 주관적 피로도 등과 같은 정성적인 평가방법을 동시에 수행하였다. 본 실험은 실제 차량에서 동일탄 구간을(호남고속도로 대전-정읍)을 왕복 주행하면서 수행되었으며, 실험에 참여한 인원은 콩 6명이었다. 실험 결과 운전시간이 증가함에 따라 근육의 피로가 증가하는 것을 볼 수 있었으며, 동시에 졸림감 또한 증가하였다. 운전 자세에 따른 피로도의 평가 결과 졸림감이 중요한 요인으로 나났는데, 이는 안락한 운전자세 뿐만 아니라 안전한 운전을 위해서도 아주 중요한 요인이라 생각된다. 본 연구는 실제 차량을 통탄 피로도의 편가를 하는데 있어서 피로를 평가하는 방법에 대탄 가이드로써 그 역할이 중분하리라 생각이 되며. 무엇보다도 실제 차량에서 실험한 결과 샘플수가적기 때문에 객관적인 결과라고 말하기엔 어렵겠지만, 운전 자세에 따라서 유의한 자이를 보였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.87-87
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• 2004

최근 철도 차량은 안전성, 정시성, 대량 수송성이 우수하여 수송수요가 증가하고 있으며, 열차운행 횟수의 증가와 차량의 고속화로 운행조건이 가혹해짐에 따라 이에 대한 절대적인 안전성과 높은 신뢰성이 요구되고 있다. 철도차량과 같이 반복하중이 연속적으로 작용하는 구조물의 설계에 있어서는 구조물의 사용 환경이나 재료의 피로특성을 최우선의 고려사항으로 간주해야 한다. 실제로 철도차량의 대차 프레임은 맞대기 용접으로 제작되어 있으며, 용접부에서 파손이 발생하고 있다.(중략)

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.832-835
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• 2011

최근까지 용접구조물의 피로설계는 용접품질 수준에 따라 공칭응력 또는 핫스팟 응력에 의한 S-N선 도로부터 수행하였다. 본 연구에서는 유한요소망의 크기에 덜 민감하면서 기존의 하중모드형식, 두께 효과 및 용접결합형식에 상관없는 등가구조응력(E2S2) 접근법을 이용한 Master S-N선도로부터 철도차량 대차프레임의 피로수명을 평가하고자 한다. 또한 합리적인 철도차량 용접대차프레임의 피로해석 연구일환으로서, 다축피로조건인 EN규격의 피로시험조건하에 이의 피로수명을 평가하고자 한다.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.151-165
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• 2000

Since vehicles become large and heavy and traffic volume is increased rapidly, many fatigue damages have been reported in bridge members. In order to prevent fatigue damages of bridge members and maintain safety it is essential to perform rational fatigue check. Only one vehicle is loaded on a bridge deck for the fatigue design. But in reality it is seldom that only one vehicle passes on a bridge deck. Usually more than two vehicles are passing on a bridge deck simultaneously. Therefore, it is necessary to consider the influence of simultaneous loading for a rational fatigue design. In this study, the influence of simultaneous loading is investigated by performing stress variation analysis due to vehicle load on the basis of linear superposition method and Monte-Carlo simulation of traffic flow, and then calculating the measure of fatigue damages.

• Journal of the Korea Convergence Society
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• v.5 no.4
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• pp.39-47
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• 2014

This study compares and analyzes the results of structural analyses due to three constraint conditions on the emblem for car. The analysis results are studied by investigating the influence due to the column angle combined between the lower plate of amblem and the upper amblem. The combined with the amblem is parallel to the longitudinal axle of the amblem at the first case. The angle combined with the amblem is perpendicular to the lower plate at the second case. The angle combined with the amblem is perpendicular to the amblem at the third case as the last case. The amblem model for car can be thought to be optimized by investigating the fatigue life and the durability of amblem through the simulation of structural and fatigue analyses. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.203-209
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• 2010

In this study, the fatigue characteristics and life of a woven glass fabric/epoxy laminate composite applied to railway vehicles was evaluated. The fatigue test was conducted using a tension-tension load with a stress ratio R of 0.1 and frequency of 5 Hz. Two types of woven glass fabric/epoxy laminate composite was used in the fatigue test: with and without carbon/epoxy ply reinforcement. In addition, the fatigue life of the woven glass fabric/epoxy laminate composite was compared with that of aluminum 6005, which is used in the car body and underframe structures of railway vehicles. The test results showed that the failure strength and life of the woven glass fabric/epoxy laminate composite reinforced with three carbon/epoxy plies had a remarkable improvement compared with that of the bare specimen without reinforcement.

• Magazine of the Korea Concrete Institute
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• v.6 no.2
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• pp.148-158
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• 1994

The goal of this study is to develop an equivalent fatigue load model for prestressed concrete composite girder bridges in Korea. To meet this goal, the probabilistic characteristics of traffics which cause fatigue damage in bridges are properly modeled. An equivalent fatigue load inodel for prestressed concrete composite girder bridges with constant. amplitude and frequency is established. The model proposed in this paper is very simple to use and gives fairly good results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1193-1199
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• 2010

Spot welding is the primary method of joining sheet metals in the automotive industry. As automobiles are subjected to fatigue loading, some spot welds may fracture before the whole system has failed. This local fracture of spot welds may lead to change in the dynamic response and consequently affect fatigue behavior of an automobile. Therefore, this change in dynamic response should be taken into consideration to assess the fatigue life of structures subjected to spectrum loading, such as automobiles. In this study, vibration fatigue analysis was performed by taking into consideration the change in the dynamic response due to accumulated damage at spot-welded parts. Fatigue tests were carried out on tensile-shear spot-welded specimens under constant amplitude loading condition. And the fatigue life of spot welds under spectrum loading was predicted using vibration fatigue analysis method based on finite element analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.819-829
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• 2008

Fatigue cracking occurs over long time period because dynamic strength of slab continuously decreases by vehicle loading repetitively applied to the concrete pavement. To more accurately predict the fatigue life of the concrete pavement, the stress due to environmental loading should be considered prior to calculating the stress due to the vehicle loading because the stress due to temperature and moisture distribution always exists within the slab. Accordingly, a new fatigue model considering the environmental loading was developed in this research by evaluating factors of existing fatigue models most widely used and by making data points from the models. The applicability of the new model was evaluated by performing a fatigue analysis on the general concrete pavement structure using local climatic and traffic conditions in Korea. It was concluded that the top-down cracking due to the tensile stress at top of the slab is dominant cause of the fatigue failure than the bottom-up cracking occurred at bottom of the slab. More advanced fatigue analysis considering vehicle speed is expected by developing this study.

• The Journal of the Acoustical Society of Korea
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• v.28 no.7
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• pp.646-652
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• 2009

In this paper, welding pitch optimization technique of vehicle subframe is presented considering the fatigue life of spot welding nuggets. Fatigue life of spot welding nuggets is estimated by using the frequency-domain fatigue analysis technique. The input data, which are used in the fatigue analysis, are obtained by performing the dynamic analysis of vehicle model passing through the Belgian road profile and also the modal frequency response analysis of finite element model of vehicle subframe. According to the fatigue life result obtained from the frequency-domain fatigue analysis, the design points to optimize the weld pitch distance are determined. For obtaining the welding pitch combination to maximize the fatigue life of the spot welding nuggets, 4-factor, 3-level orthogonal array experimental design is used. This study shows that the optimized subframe improves the fatigue life of welding nugget with minimum fatigue life about 65.8 % as compared with the baseline design.