• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.60-63
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• 2000

In this study, efficient force reflection algorithm is developed for the Haptic Display by using a proxy concept and friction model. When there are not any contacted obstacles the proxy is following human operator's command trajectory in the 3D virtual space. But when the operator's command trajectory is locating inside of the object, the proxy is constrained by the surface of the object. Here only with the information of the proxy position and operator's command trajectory at every time step, we can calculate the reflection force and its orientation. To display the friction force between two virtual stiff material which are sliding against each other, modified Karnopp's friction model is used. In the friction model, a damping term and a Stribeck effect term are included to display the relative velocity effect and stick-slip effect at the very low relative velocity region respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.79-84
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• 2001

The motivation behind this work is to understand the phenomenon of friction-induced vibration and squeal due to misalignment. In present paper, it is studied on effect of misalignment between friction-induced vibration and squeal by an experiment using a pin-on-disk type experimental apparatus. In order to build an analytical model of the friction-induced vibration system with misalignment, the system is modeled as a single-DOF and 3-DOF system. The results show that the single DOF system can only show stick／slip phenomenon, but the 3-DOF system can show squeal due to misalignment. Consequently, it can be said that the misalignment in a friction-induced vibration system is a source of squeal noise.

• 한국음향학회지
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• 제39권2호
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• pp.98-104
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• 2020

에어컨 운전 중에 발생하는 실내기의 수축팽창 소음 현상을 분석하고, 발생위치를 평가한다. 그리고 마찰실험을 통하여 수축팽창 소음을 유발하는 인자를 규명하고자 한다. 먼저 항온·항습챔버에서 운전 환경 조건별로 수축팽창 소음의 발생횟수 및 특성을 분석하고, 분해법을 이용하여 냉방 및 난방 시 모두 하부 데코에서 발생하는 것을 확인하였다. 실내기에서 발생하는 수축팽창 소음은 하부 데코와 연결되는 부품들과의 체결부에서 발생하는 스틱슬립 현상에 의한 것으로 이러한 소음을 유발하는 인자를 규명하기 위하여 마찰실험을 진행하였다. 또한 마찰실험 결과의 효과적 분석을 위하여 십점평균 산출법을 도입하고, 실험 결과에서 Acrylonitrile Butadiene Styrene(ABS) 재질 간에 접촉하면 스틱슬립 현상을 유발하며 체결부의 양면에 표면조도를 증가하는 것이 소음저감에 효과적임을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제18권10호
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• pp.1755-1762
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• 2004

Friction phenomenon can be described as two parts, which are the pre-sliding and sliding regions. In the motion of the sliding region, the friction force depends on the velocity of the system and consists of the Coulomb, stick-slip, Streibeck effect and viscous frictions. The friction force in the pre-sliding region, which occurs before the breakaway, depends on the position of the system. In the case of the motion of the friction in the sliding region, the LuGre model describes well the friction phenomenon and is used widely to identify the friction model, but the motion of the friction in the pre-sliding such as hysteresis phenomenon cannot be expressed well. In this paper, a modified friction model for the motion of the friction in the pre-sliding region is suggested which can consider the hysteresis phenomenon as the Preisach model. In order to show the effectiveness of the proposed friction model, the sliding mode controller (SMC) with hysteresis friction compensator is synthesized for a ball-screw servo system.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.55-63
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• 2001

Friction and wear properties of brake friction materials containing different metal fibers (Al, Cu or Steel fibers) were investigated using a pad-on-disk type friction tester. Two different materials(gray iron and Al-MMC)) were used for disks rubbing against the friction materials. Results from ambient temperature tests revealed that the friction material containing Cu fibers sliding against cast iron disk showed a distinct negative ${\mu}$-ν (friction coefficient vs. sliding velocity) relation implying possible stick-slip generation at low speed. The negative ${\mu}$-ν relation was not observed when the Cu-containing friction materials were rubbed against the. Al-MMC counter surface. As applied loads increased, friction materials showed higher friction coefficients comparatively. Friction materials slid against cast iron disks exhibited higher friction coefficients than Al-MMC disks during high temperature tests. On the other hand, high temperature test results suggested that copper fibers in the friction material improved fade resistance and the steel fibers were not compatible with Al-MMC disks showing severe material transfer and erratic friction behavior during sliding at elevated temperatures.

• Transactions on Control, Automation and Systems Engineering
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• 제3권2호
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• pp.111-116
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• 2001

A neural network compensator for stick-slip friction phenomena in meashartonics servo systems is practically proposed to supplement the traditionally available position and velocity control loops for precise motion control. The neural network compensa-tor plays the role of canceling the effect of nonlinear slipping friction force. It works robustly and effectively in a real control system. This enables the mechatronics servo systems to provide more precise control in the digital computer. It was confirmed that the con-trol accuracy is improved near zero velocity and points of changing the moving direction through numerical simulation. However, asymptotic property on the steady state error of the normal operation points is guaranteed by the integral term of traditional velocity loop controller.

• 한국정밀공학회지
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• 제19권10호
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• pp.163-170
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• 2002

The dynamic model of a high-speed vacuum circuit breaker mechanism with spring-actuated cam and linkage is derived to simulate the high-speed closing and opening operations. Its validation for an analysis of high-speed motion behavior is checked through experiments. The characteristics of the friction on the camshaft are investigated using the nonlinear pendulum experiment. The parameters of the friction model are estimated using the optimization technique. The analysis exhibits that the friction of the pendulum depends on stick-slip, Stribeck effect and viscous damping. Comparing simulation results with actual responses using a high-speed camera, the appropriateness of derived dynamic models for the rapid closing and opening operations is shown. The spring motion, which has much influence on the closing responses, is observed.

• KSTLE International Journal
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• 제3권1호
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• pp.49-53
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• 2002

Inconel 690 for nuclear steam generator tube has more chromium than the conventionally used Inconel 600 in order to increase the corrosion resistance. TD evaluate the tribological characteristics under fretting condition the fretting tests as well as sliding tests were carried out in elevated temperature water environment. Fretting tests of the cross-cylinder type were done under various vibrating amplitudes and applied normal loads in order to measure the friction forces and wear volumes. Also, the conventional sliding tests of pin-en-disk type were carried out to compare the test results. In fretting, the friction was very sensitive to the load and the amplitude. The friction coefficient decreased with increasing load and decreasing amplitude. Also, the wear of Inconel 690 can be predictable using the work rate model. Depending on normal loads and vibrating amplitudes, distinctively different wear mechanisms and of ten drastically different wear rates can occur. It was fecund that the fretting wear coefficients in water were increased as increasing the temperature of water.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.485-486
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• 2006

This paper represents a ultra precision rotational device where the smooth impact drive mechanism(SIDM) is utilized as a driving mechanism. Linear motions of piezoelectric elements are converted to the rotational motion of disk by frictional forces generated between the rotational disk and the friction bars which are attached to the piezoelectric elements. This device was designed to drive a rotational disk using slip-slip motion mechanism based on stick-slip motion mechanism. Experimental results show that the angular velocity was increased in proportion to the magnitude of supplied voltage to piezoelectric element. In our device, the smooth rotational motion was obtained when the driving frequency has been reached to 500Hz under the driving voltage of 100V. The amount of step movement has been revealed to be $3.44{\times}10^{-4}$ radian.

• 한국전산구조공학회논문집
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• 제23권2호
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• pp.199-208
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• 2010

건물에 설치된 마찰감쇠기는 외력의 크기에 따라 정지와 운동의 상태를 반복하여 외부 입력에너지를 소산시키기 때문에 외력과 응답관계가 비선형이다. 마찰감쇠기가 설치된 단자유도 건물은 마찰감쇠기외에 점성감쇠가 동시에 존재하므로 해석적인 정해를 구하기가 어렵다. 본 연구에서는 첫째, 점성과 마찰감쇠가 있는 단자유도계 건물의 자유진동 정해를 통하여 변위응답과 가속도 응답특성을 분석하였다. 둘째, 자유진동의 경우 응답이 멈출 때까지 소산에너지식을 이용하여 등가점성감쇠비를 구하였다. 셋째, 조화가진 일 때는 수치해석을 통하여 마찰력비 $F_r$에 따른 응답 특성을 알아보았다. 넷째, 조화가진의 경우 에너지 균형식을 바탕으로 등가점성감쇠비를 유도하였다. 등가점성감쇠비는 변위응답비의 영향을 받으므로 응답을 알아야만 구할 수 있다. 건물 응답의 진동수 특성은 협소영역(narrow band)이므로 고유진동수에 의해 지배된다고 가정하여 등가점성감쇠비를 구하였다. 마지막으로, 유도한 자유진동과 조화가진의 등가점성감쇠비를 이용한 등가선형운동방정식의 해를 비선형 수치해석 한 결과와 비교하여 검증하였다.