• 한국전산구조공학회논문집
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• 제36권2호
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• pp.121-130
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• 2023

기어의 구조 안정성 및 치물림 성능을 분석하기 위하여 유한요소해석이 널리 사용된다. 본 연구에서는 스퍼 기어의 유한요소 모델링 조건이 해석 결과 및 간소화 효과에 미치는 영향을 분석하였다. 기어 구조 해석의 간소화 방법으로 기어 몸체 및 잇수 간소화, 요소망 생성 방식, 접촉 및 마찰 조건, 해석 조건 등을 선정하였다. 기어의 성능해석 지표로써 1주기의 기어 치물림 사이클 동안의 정전달 오차를 계산하였고, 간소화 지표로써 해석 소요 시간을 측정하였다. 유한요소해석을 통해 치물림 주기에 따른 접촉 응력 분포 및 변화 양상을 확인하였다. 모델링 조건에 따라 최대 전달 오차와 해석 소요 시간에 차이를 확인하고 원인을 분석하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.383-384
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• 2002

Frictional sound is observed in great many practical systems, but its generation mechanism is still unknown Model systems are best suited for research on the fundamental mechanisms, but results cannot be easily applied to real systems, because each system has different sound radiation properties. At present, there is no easy method for evaluation of these properties. We propose to describe the sound radiation property of a tribo-system by the relationship between friction-induced sound power and the friction-induced vibration velocity of the contact element. It was found that the sound power of a tribo-system is linearly proportional to the mean-square velocity of the sliding element by a constant coefficient having the dimension of mass flow rate (kg/s).

• Tribology and Lubricants
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• 제7권1호
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• pp.55-60
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• 1991

The emulsion lubrication is expected to get the effects of cooling and lubrication in metal cutting. The purpose of this research was to investigate the lubrication characteristics of the emulsion in a region of the elastohydrodynamic lubrication by experiments using o/w type emulsion lubrication. With the line contact frictional experiment apparatus which is the model of a rolling mechanism, friction coefficient, and oil film thickness were measured. By analyzing these experimental data with the variables of emulsion concentration, load, and rolling velocity, the following results are obtained. Emulsion viscosity $\eta$ for the concentration and pressure can be calculated by the following equation $\eta=\eta_o e^{\alphap}\cdot e^{\beta \phi}$. Where $\beta = (-3.7242+\phi)/\phi, 5%\leq \phi \leq 15%$.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.735-742
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• 2001

This paper reports on the dynamics and friction characteristics of piston skirt with consideration of mixed lubrication. Piston skirt is an important part of the engine that transforms fuel into mechanical energy. The durability and low friction characteristics are important recent issues in piston skirt design. In this paper, the piston skirt motion is analyzed with consideration of mixed lubrication and piston skirt tilting motion. The entire trajectory of piston motion is obtained by using transient numerical method. Also various parameter studies are performed for piston skirt design and the development of lower frictional engine.

• Tribology and Lubricants
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• 제30권1호
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• pp.36-45
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• 2014

Understanding steel/skin contact phenomena is important for the study of object manipulation in robotics and has been a topic of great interest. In this study, pig skin was taken as a surrogate model for human skin, and its adhesive, friction, and deformation behaviors were measured under various exposure times to air. Indentation, friction, and scratch tests were performed at $25^{\circ}C$ and 45% relative humidity. The influences of adhesion and deformation on the coefficient of friction were characterized; the pig skin was found to be sensitive to the sliding velocity and normal load under the controlled experimental conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.422-422
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• 2000

Parallel manipulators have been used to a variety of applications, including the motion simulators and mechanism for precise machining. A Stewart-Gough type parallel manipulator is composed of six linear joints which have wider contact areas than revolute ones, so linear joints are more affected by frictional force. First, the reference trajectories are computed from the model of the parallel manipulator assuming that it is subject to only the gravitational force and no friction exists. In the actual operation where friction exists, the control inputs, which correspond to the friction forces, are obtained by forcing the actual joint variables to follow these trojectories by proper control. It is shown that control performance can be improved when the friction compensation based on this information is added to the controller for position control of the moving plate of a parallel manipulator.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.164-170
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• 2008

A typical clutch system for automotive manual transmissions transfers hydraulic pressure generated by driver's pedal manipulation to the clutch diaphragm spring. The foot effort history during the period of push is different than the period of the clutch pedal's return. The effort or load difference is called clutch foot effort hysteresis. It is known that the hysteresis is caused by friction. The frictional force and moment are produced between various component contact points such as between the rubber seal and the inner wall inside the hydraulic cylinder and between the diaphragm spring and the pressure plate, etc. Understanding the clutch pedal foot effort hysteresis is essential for a clutch release system design and analysis. The dynamic model for a clutch release system is developed for the foot effort hysteresis prediction and a simulation analysis is performed to propose a tool for analysing a clutch system.

• 한국정밀공학회지
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• 제20권3호
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• pp.140-148
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• 2003

An analysis fur the warping process has been performed to design the warper beam. Nonlinear material response is included in the physical model of polyester yarn. Large deformation finite element simulation considering contact and frictional analysis are used to obtain the pressure on the barrel of the warper beam. Loading condition on the flange is assumed by using the pressure on the barrel, winding number of yarn, Poisson's ratio of fiber, and fiber volume fraction. By using the above loading conditions NASTRAN finite element simulation is performed to calculate stress distribution and deformation of the warper beam. By comparing the deformed shape of the flange with experimental result, loading condition on the flange has been obtained. The obtained loading conditions on the barrel and flange can be utilized to design the warper beam.

• Structural Engineering and Mechanics
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• 제46권4호
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• pp.533-547
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• 2013

"Reciprocal Frame" refers to a self-supporting grid structure used both for floor and roof. Using Finite Element Methods for non-linear solid mechanics and frictional-contact, this paper intends to analytically and numerically investigate the collapse behaviour of a reciprocal frame structure made of fibre-reinforced concrete. Considering a simple 3-beam structure, it has been investigated using a solid finite element model. Once defined the collapse behaviour of the simple structure, the analysis has been generalized using a concentrated plasticity finite element method. Results provided will be useful for studying generic reciprocal frame structures with several beams.

• 대한기계학회논문집A
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• 제38권5호
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• pp.545-550
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• 2014

본 연구는 복잡한 빔 구조체의 마찰에 의한 소음을 유한요소기법을 이용하여 예측하였다. 마찰접촉 모델을 수학적으로 유도하여 유한요소기법에 접목하였다. 그 결과 빔 구조체의 특정 모드에서 모드 연성에 의해서 동적 불안정성이 유발되고 있음을 보여주었다. 또한 마찰의 방향이 모드 불안정성에 매우 큰 영향을 미치고 있음을 보여주었다. 또한 실제 빔 구조체 시스템을 제작하여 해석에서 예측한 특정 주파수에서 소음 피크주파수가 발생하고 있음을 실험적으로 검증하였다.