• 한국자동차공학회논문집
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• 제10권1호
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• pp.203-208
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• 2002

In order to reduce the booming noise caused by first bending mode of a drive shaft, this paper proposes a simulation program for prediction of the bending mode frequency of any tubular shaft. This program consists of a pre-processor for modeling of geometrical shape of the drive shaft with boundary conditions of various joints, a processor for constructing of global finite element matrices using beam elements and an eigen-solver based on MATLAB program. Using this simulation program, the effective and accurate FE model far a shaft attached to vehicle can be obtained by aid of database for stiffness of each joint. Thus the resonance frequencies and mode shapes of a shaft can be calculated accurately. Because the effect of the resonance on interior noise can be verified, more improved shaft will be proposed at the early stage of design.

• 소음진동
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• 제9권3호
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• pp.461-465
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• 1999

This paper presents theoretical analyses for unstable vibrations caused by the couple of bending and torsion in a rotating shaft driven through a universal joint. A driving shaft is assumed to be rigid and to rotate with a constant angular velocity. The driven shaft system consists of a flexible shaft with a circular section and a symmetrical rotor attached at a point between the shaft ends. Equations of motion derived hold with an accuracy of the second order of shaft deformations, and are analyzed by the asymptotic method. The vibrations become unstable when the driving shaft rotates with the angular velocity to be approximately equal to half of the sum of the natural frequencies for whirling and torsional vibrations.

• International Journal of Automotive Technology
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• 제8권4호
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• pp.521-531
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• 2007

Measurement of the vibration transmitted through rotating shafts such as half shafts in vehicles is of interest in applications such as noise transfer analysis and the study of operating deflections. Vibration signals transmitted through a rotating shaft usually include six degree-of-freedom components, thus making the measurement of vibration a challenging task. In the present work, a new measurement method is presented, one that resolves the minimum of only two one-axis accelerometer signals into all components of vibration with reasonable accuracy. The method utilizes the Dopplerized signals obtained from accelerometers attached to a rotating shaft and a Void-Kalman order tracking filter to decompose signals into orders of different vibration components. The new method proposed in the present work is verified by simulated run-up test data and applied to an experimentally obtained data set.

• 한국정밀공학회지
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• 제16권11호
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• pp.55-61
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• 1999

The torsional and axial vibrations of shaft system have been calculated independently because of both the limitation of computing time and the complexity of crankshaft model. In actual system, however, the torsional and axial vibrations are coupled. Therefore, in recent, many works in the coupled vibration analysis have been done to find out the more exact dynamic behavior of shaft system. The crankshaft model is very important in the vibration analysis of shaft system because most of excitation forces act on the crankshaft. It is, however, difficult to establish an exact model of crankshaft since its shape is very complex. In this work, an efficient method is proposed to construct the stiffness matrix of crankshaft using a finite element model of half crankthrow. The proposed and existing methods are compared by applying to both a simple thick beam with circular cross section and an actual crankshaft.

• 대한기계학회논문집A
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• 제24권7호
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• pp.1740-1747
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• 2000

Under repeated rolling, initial plastic deformation introduces residual stresses which render the steady cyclic state purely elastic. This is called the process of shakedown. Many studies have been done about the shakedown in semi-infinite half space using calculated Hertizian pressure. In this paper shakedown processes in a shaft are studied by finite element analyses of a two dimensional(plane strain) model with elastic-linear-kinematic-hardening-plastic material subjected to repeated, frictionless rolling contact. Symmetric and non-symmetric pressure distributions are obtained using a simplified model of the bearing-shaft assembly. The rolling contact is simulated by repeatedly translating both pressure distributions along the surface of the shaft. By the influence of the non-symmetric pressure, larger residual radial tensile stress is generated in the immediate subsurface layer, which may make a crack propagate and, the subsurface undergoes a zigzag plastic deformation during the shakedown process, which may lead to a crack initiation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.153-158
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• 2006

Nowadays, hollow upper-shaft of monobloc type has been considered for weight reduction and high quality in the automobile industry. To form the upper-shaft under tube cold extrusion, Taguchi method is applied to optimize the die design in this study. Taguchi method for optimum die design is to establish the optimal combination of design parameters and to reduce a number of experiments. Effect of parameters including the die relief, mandrel, die half angle is investigated and analyzed based on FEA analysis using a FEM commercial software MSC_Marc. Furthermore extrusion experiments have been performed to verify the results investigated in the FEM simulations.

• 한국지반공학회논문집
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• 제19권5호
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• pp.109-122
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• 2003

기존 철도터널의 운행속도 향상시 문제가 되는 터널내 공기의 압축파 문제를 해결하기 위해서는 단면의 화대보다는 통풍공 수직구의 건설이 경제성 및 시공성 측면에서 유리한 것으로 알려져 있다. 본 연구에서는 장기재령의 운영중인 철도터널에 통풍공 수직구를 건설함에 따라 발생될 수 있는 본선터널, 하부갱도 그리고 수직구의 역학적 거동들을 파악하기 위한 목적으로 3개의 독립적인 요소기술들에 대하여 실험적, 해석적 연구를 수행하였다. 연구결과, 먼저 장기재령과 콘크리트 라이닝의 강도관계는 재령이 증가함에 따라 강도가 저하하는 경향을 확인할 수 있었으며, 본선터널과 수직구의 최소 적정이격 거리를 해석적으로 추정한 결과는 본선터널 직경(D)의 약 0.5D 이상이 적합한 것으로 도출되었다. 다음으로 수직구 굴착에 따른 하부갱도의 3차원적 거동은 시험시공의 계측결과와 탄소성 유한요소해석 결과가 유사한 경향을 나타내었으나, 수직구 굴착시 수직구 자체의 거동파악을 위한 분석결과에서는 수직구의 심도별 지반거동 계측결과와 3차원 유한요소해석 결과가 상이한 거동을 보였다. 따라서 이상의 연구결과로부터 수평터널에 대한 해석결과와 계측결과의 경향은 유사하지만 변위, 응력 등의 정량적 비교에서는 지반물성치의 선정방법에 따라 다소 큰 차이가 나타남을 알 수 있었다. 또한 수직방향에 대한 거동을 해석적인 방법으로 검증하기 위해서는 지표면에서의 수평방향 응력, 변위성분을 표현할 수 있는 적정기법 연구가 요구된다.

• Journal of Biosystems Engineering
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• 제23권3호
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• pp.245-252
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• 1998

The structural characteristics of a small scale rice polisher was analyzed to improve its performance. Spraying characteristic of nozzles used for rice polishing was also analyzed by a machine vision system. The internal pressure of the polishing chamber was measured according to outlet resistance, water spraying, and roller shaft speed. In addition, the performance of the rice polisher was evaluated to improve it in the basis of internal pressure in polishing chamber, whiteness, and broken rice ratio of clean rice according to the operating conditions. Actual nozzle discharge rate and drop size were 125 cc/min and 86~97 ${\mu}{\textrm}{m}$, respectively. In the case of water spraying on rices, the internal pressure showed 4.9~9.8N/$\textrm{cm}^2$ increase. broken rice ratio decreased, and there was no difference in whiteness. The internal pressure inueased up to two times with the increase of the outlet resistance. Also, the pressure at the upper part of screen was one and half times as high as the pressure at the lower part. In the case of water spraying rate of 150 cc/min, the roller shaft speed of 850 rpm resulted in no difference in whiteness and decrease of 0.3% in broken rice ratio, comparing to the roller shaft speed of 950 rpm.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1998년도 하계 학술대회 논문집
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• pp.206-216
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• 1998

The structural characteristics of small scale rice polisher was analyzed to improve its performance. Spraying characteristic of nozzles used for rice polishing was also analyzed by a machine vision system. The internal pressure of the polishing chamber was measured according to outlet resistance, water spraying , and roller shaft speed. In addition , the performance of the rice polisher was evaluated to improve it in the basis of internal pressure in polishing chamber, whiteness , and broken rice ratio of clean rice according to the operating conditions. Actual nozzle discharge rate and drop size were 125cc/min and 86.97㎛, respectively. In the case of water spraying on rices, the internal pressure showed 4.9-9.8N/㎠ increase, broken rice ration decreased , and there was no difference in whiteness . The internal pressure increased up to two time with the increase of the outlet resistance. Also, the pressure at the upper part of screen was one and half times as high as the pressure at the lower part. In the case of water spraying rate of 150 cc/min, the roller shaft speed of 850 rpm resulted in no difference in whiteness and decrease of 0.3%in broken rice ratio, comparing to the roller shaft speed of 950 rpm.

• Tribology and Lubricants
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• 제25권4호
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• pp.225-230
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• 2009

Seals are very useful machine components in protection of leakage of lubricant or working fluid, and incoming of debris from outside. Various elastomer are widely used as sealing materials and the shaft surfaces are generally coated with high hardness material after heat treatment. It is generally known that the foreign debris and wear particles get stuck into sealing surface, the steel shaft surface can be damaged and worn by mainly abrasive wear. In this paper, using MARC, contact analysis are conducted to show the hard coated steel shaft surface can be fatigue failed by very small elastic particle intervened between seal and steel surface. Variations of contact and von-Mises stress distributions and contact half-widths with interference and coating thickness are presented. The maximum von-Mises stress occurs always in the coating layer or between coated layer/substrate interface. Therefore the coated sealing surface can be fatigued and then failed by very small particles. The results can be used in design of sealing surface and further studies are required.