• 대한기계학회논문집
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• 제18권12호
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• pp.3149-3158
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• 1994

In this paper, using the formulation of dynamic equivalent load considering the effects of moment load and the equation to estimate the cage rotational speed, the new life equation of deep groove ball bearing under radial and moment loads was proposed. Fatigue life test apparatus with the measuring equipment of shaft and cage speed was designed and developed to be capable of subjecting combined radial and moment load. Fatigue life tests were executed by sudden death test method and the reliability of fatigue lives was evaluated by Weibull distribution analysis. From the results of fatigue tests and analysis, the relationships between film parameters and life adjustment factors were acquired. And it was turned out that so as to estimate the effect of moment load on fatigue life, the life adjustment factor as well as the dynamic equivalent load must be taken into account.

• 자동차안전학회지
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• 제14권3호
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• pp.30-34
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• 2022

The CFT(Cornering Fatigue test) and RFT(Radial Fatigue Test) are tests for evaluating the endurance of the disc and rim region of the wheel. In recent, automobile wheel safety standards have been revised and the applied load and target life criteria are different from existing conditions. The verification evaluation of all wheels requires a lot of time and cost. In this study, the endurance severity of each test was compared through strain-life approach by selecting 4 steel and 8 aluminum wheels.

• 대한기계학회논문집A
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• 제27권9호
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• pp.1444-1450
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• 2003

The fatigue life and tensile strength of JLF-1 steel (Fe-9Cr-2W-V-Ta) and its TIG weldment were investigated at the room temperature and $400^{\circ}C$. Four kinds of test specimens, which associated with the rolling direction and the TIG welding direction were machined. The base metal of JLF-1 steel represented almost anisotropy in the tensile properties for the rolling direction. And the base metal of JLF-1 steel showed lower strength than that of TIG weldment. Also, the strength of all materials entirely decreased in accordance with elevating test temperature. Moreover, the fatigue limit of weld metal was largely increase than that of base metal at both temperatures. The fatigue limit of JLF-1 steel decreased in accordance with elevating test temperature. The fatigue limit of JLF-1 steel decreased in accordance with elevating test temperature. The SEM fractography of tensile test specimen showed conspicuous cleavage fracture of a radial shape. In case of fatigue life test specimen, there were so many striations at crack initiation region, and dimple was observed at final fracture region as a ductile fracture mode.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3837-3851
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• 2021

To investigate how the fabrication and repair of socket welded joints could be used to enhance fatigue resistance under vibration condition, experimental test data of installation conditions that potentially influence fatigue strength were analyzed with the S-N curve. It was found that the decreasing fatigue strength of stainless steel socket welded joints was attributed to the effect of high heat input of welding process. The effect of welding method, slip-on gap and radial-gap conditions on fatigue strength was insignificant. The test data of repair technique application, 2 × 1 leg length and of socket weld overlay, clearly showed higher fatigue strength but there was a limitation for higher stress region because of the weld toe crack.

• 한국자동차공학회논문집
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• 제11권6호
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• pp.147-154
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• 2003

Radial Dual Mass Flywheel(RDMF) is designed to reduce torsional vibration and noise occurring in automotive powertrain. In this paper, finite element method is used to evaluate stress level and critical area of the torsional spring box, a major part of RDNF system. In finite element analysis, both static and dynamic loadings are considered and it is found that the most critical spot is the welded zone of spring box. Also, fatigue test is performed and fractured surfaces are examined to find fatigue stress level by experiment.

• 대한한의학원전학회지
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• 제34권2호
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• pp.85-94
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• 2021

Objectives : Pulse diagnosis is one of the main diagnostic methods of Korean Medicine that understands the patient's condition and illness by reading changes in the patient's pulse, which is described in terms of pulse condition While they are described in detail in medical texts, it is difficult to grasp their true nature, as the written descriptions fail to do justice to the experience of pulse taking it tries to convey. As a way to approach pulse condition the effect of the body's tension on the radial vein was measured using an ultrasonic device, after which the measured changes and how they could be reflected in pulse condition were studied. In other words, changes in the radial vein following induced tension were analyzed. Methods : 1) The thickness of the subject's radial vein was measured using a linear probe of an ultrasonic device[LOGIQ 5 Basic, GE, USA]. 2) Fatigue level was increased through artificial stimulation using the Gripmeter[ks-301, Lavisen, Korea]. 3) Thickness of the radial vein post tension induction was measured. 4) The results were analyzed with the Tukey test or paired t-test as post hoc tests. Results : Thickness of the radial vein of the subject pre- and post- Gripmeter stimulation decreased with significance. Conclusions : Constriction of the radial vein that happened after tension induction could be linked to the Tight Pulse[緊脈] that is related to patterns of contraction and pulling.

• 대한기계학회논문집
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• 제14권5호
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• pp.1320-1329
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• 1990

본 연구에서는 토크로드의 여러가지 성능시험이 하능한 시험기의 설계와 개발 에 관하여 논하려 한다. 토크 로드의 정적 성능은, 반경방향 스프링 특성시험 및 비 틀림 방향 스프링 특성시험 그리고 회전토크 특성시험 등을 통하여 평가된다. 그러 나, 이들 세가지 성능시험을 위한 시험기를 각각 개발할 경우 소요비용이 과다해진다. 따라서, 한정된 예산과 시험기 개발후 시험평가 공정의 간소화 등을 고려하여, 본 시 험기는 3대의 시험기로써 하여야 할 기능을 한대의 시험기로써 할수 있도록 개발하였 다. 시험기 개발에 따른 기술적인 고찰과, 본 시험기로 정하중에서의 토크 로드 부 품의 성능시험을 수행하고 서어보 유압식 구조물 피로 시험기를 사용하여 동 부품의 피로 내구성 시험을 실시하고, 고무의 조성변화, 접착성 개선 등을 통해 내구성을 향 상시킴으로 국산화 개발을 가능케 한 기술적 내용들을 살펴 보고자 한다.

• 대한기계학회논문집
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• 제15권6호
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• pp.1839-1851
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• 1991

Fatigue crack behavior is studied through the two-level rotary bending test with the deep non-through radial holed notch specimens of low carbon steels(SM22C). The main factors investigated are the effects of the damage zone size around crack tip and phenomena of closing or opening of the crack tip. Obtained results are summarized as follows. Fatigue crack behavior in second level stressing slightly lower than fatigue limit is closely related to the size of damage zone produced by the first level stress higher than fatigue limit and to the phenomena of crack closing and opening for the second level stress. The non-propagating crack limit condition depends upon the crack length l$_{1}$ propagated under the first level stress and the magnitude of second level stress .sigma.$_{2}$ lower than the fatigue limit. The non-propagating crack limit condition is expressed by following eq. $\sigma_2^{6.1}{\times}l_{1}=7.35{\times}10^{6}[(kg_{f}mm^{6.1}(mm)]$

• 자동차안전학회지
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• 제8권1호
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• pp.26-30
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• 2016

The steel road wheel on ventilation holes was cracked in the vehicle durability test. But the component durability test by uni-axial, CFT(Cornering Fatigue Test) and RFT(Radial Fatigue Test) had been satisfied. That is, the uni-axial component test could not forecast the crack of vehicle. Therefore this study developed the bi-axial test mode to reflect a vehicle condition(to reflect both vertical and lateral force simultaneously) based on real load data which was measured in Europe and China and developed CAE simulation too. It reproduced the cracks same as vehicle's and verified by bi-axial test machine in the LBF(Fraunhofer Institute for Structural Durability and System Reliability) durability research center in Germany. Finally this the durability CAE simulation by using HMC(Hyundai Motor Company)'s the bi-axial test mode predicts feasibly the steel wheel's durability performance before vehicle durability test.

• 한국결정성장학회지
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• 제14권5호
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• pp.199-203
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• 2004

유사구강 분위기인 인공타액 조건하에서 인공치아용 상부구조물 재료 중 하나인 3Y-TZP를 500~3000 N의 하중 조건으로 $10^6$ 횟수까지 헤르찌안 반복하중을 가하여 그 피로특성을 압입손상과 강도저하현상으로 관찰하였다. 500 N의 하중에서 $5\times10^5$ 반복 횟수까지 피로실험결과, 강도저하 및 균열현상은 관찰되지는 않았지만 반복하중 값이 증가함에 따라 링 균열에서 방사상 균열로 전이되었을 때 급격한 강도 저하현상이 관찰되었다. 또한 강도 저하 현상은 유사 구강분위기하에서 반복 하중 접촉시 발생한 균열을 통해 침투한 인공타액의 화학적 침식으로 가속화 되었다.