• 대한기계학회논문집A
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• 제40권2호
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• pp.199-206
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• 2016

LM 볼가이드는 구름접촉을 갖는 이송시스템의 핵심요소로서 공작기계, 반도체 장비, 로봇 등 정밀기계에 널리 사용된다. 그러나 LM 볼가이드에서 발생하는 마찰력은 마찰열을 유발하여 위치 정도를 저하시키고 강성과 예압 변화를 야기한다. 이런 영향을 정확하게 분석하여 정밀 기계설계에 응용하기 위해서는 마찰력 모델의 정식화가 요구된다. 본 논문에서는 구름마찰, 점성마찰, 슬립마찰을 고려한 LM 볼가이드의 정확한 마찰력 모델을 유도한다. 그리고 다양한 조립, 부하 및 속도 조건에서 실험을 수행하여 마찰력 모델의 신뢰성을 검증하고, 마찰력 모델로부터 마찰 성분의 영향력을 분석한다.

• International Journal of Automotive Technology
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• 제8권2호
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• pp.211-217
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• 2007

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS (Anti-lock Brake System) systems. In realizing the wheel slip control systems, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance and stability enhancement. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm is proposed for maximizing the braking force. An adaptive law is formulated to estimate the braking force in real-time. The wheel slip controller is designed based on the Lyapunov stability theory considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm searches for the optimal target slip value based on the estimated braking force. The performance of the proposed wheel slip control system is verified in HILS (Hardware-In-the-Loop Simulator) experiments and demonstrates the effectiveness of the wheel slip control in various road conditions.

• 한국정밀공학회지
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• 제14권4호
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• pp.88-96
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• 1997

This paper suggests a new non-linear friction compensation for digital control systems. This control adopts a hysteresis nonlinear element which can introduce the phase lead of the control system to compensate the phase delay comes from the inherent time delay of a digital control. A proper Lyapunov function is selected and the Lyapunov direct method is used to prove the asymptotic stability of the suggested control.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.987-993
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• 1996

This report suggests a new non-linear friction compensation for digital control systems. This control adopts a hysteric nonlinear clement which can introduce the phase lead of the control system to compensate the phase delay comes from the inherent time delay of a digital control. The Lyapunov direct method is used to prove the asymtotic stability of the suggested control, and the stability and the effectiveness are verified analytically and experimentally on a single axis servo driving system.

• 대한기계학회논문집
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• 제15권1호
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• pp.163-168
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• 1991

본 연구에서는 여러가지의 성형조건에서 미끄름을 지배하는 상수를 측정하고, 유동 선단(flow front)에 미치는 이 상수의 영향을 검토한다. 또 측정된 상수를 가 지고 사각형 및 중공 원형 평판 압축성형에 대해서 2차원 유한 요소해석을 하고 실험 결과와 비교 검토한다.

• Steel and Composite Structures
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• 제29권1호
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• pp.107-123
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• 2018

The conception and experimental assessment of a removable friction-based shear connector (FBSC) for precast steel-concrete composite bridges is presented. The FBSC uses pre-tensioned high-strength steel bolts that pass through countersunk holes drilled on the top flange of the steel beam. Pre-tensioning of the bolts provides the FBSC with significant frictional resistance that essentially prevents relative slip displacement of the concrete slab with respect to the steel beam under service loading. The countersunk holes are grouted to prevent sudden slip of the FBSC when friction resistance is exceeded. Moreover, the FBSC promotes accelerated bridge construction by fully exploiting prefabrication, does not raise issues relevant to precast construction tolerances, and allows rapid bridge disassembly to drastically reduce the time needed to replace any deteriorating structural component (e.g., the bridge deck). A series of 11 push-out tests highlight why the novel structural details of the FBSC result in superior shear load-slip displacement behavior compared to welded shear studs. The paper also quantifies the effects of bolt diameter and bolt preload and presents a design equation to predict the shear resistance of the FBSC.

• 한국강구조학회 논문집
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• 제12권2호통권45호
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• pp.177-185
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• 2000

본 논문에서는 대기 중에 폭로한 내후성강재의 고장력볼트 마찰이음부 미끄럼계수 평가를 위한 실험연구를 수행하였다. 표면 상태는 흑피 부착된 시험체와 숏브라스트로 흑피를 제거한 시험체를 각각 3개월 및 6개월 폭로한 후 수동솔질, 전동솔질 및 청소하지 않은 표면 등을 고려하였다. 또한, 6개월 폭로 시험편의 각 표면 상태에 대하여 600 시간 동안 볼트축력 감소율을 측정하였다. 실험으로부터 모든 시험체에서 폭로 기간에 따라 미끄럼 계수는 증가하였으며 흑피부착 표면을 전동솔질로 청소한 경우를 제외하곤 모두 0.6 이상의 값을 보였다. 볼트 축력 감소율 역시 초기 비폭로 시험체에 비해 폭로한 시험 체에서 증가하였으며 최대 감소율은 약 10%에 이르렀다.

• KSTLE International Journal
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• 제1권1호
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• pp.1-7
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• 2000

Eviction characteristics of two typical friction materials (non-asbestos organic and low-steel friction materials) for an automotive brake system were investigated using an inertial brake dynamometer. In particular, the effect of sliding speed on friction coefficient was carefully investigated employing various test modes. The two friction materials were developed for commercial applications and were different mainly in the type and the amount of metallic ingredients in the friction material. The dynamometer test showed that the low-steel friction material was sensitive to the sliding speed exhibiting a negative $\mu$-v relation. On the other hand, the non-asbestos organic friction material was less sensitive to the sliding speed. The low steel friction materials with a negative $\mu$-v relation also induced larger vibration amplitude during brake applications.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제23회 학술대회
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• pp.1-3
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• 1996

The characteristics of fretting wear are reviewed. Fretting damage depends on slip amplitude and classified into three groups: (1) an annular damage according to Mindlin's analysis at microslip region, (2) strong adhesive deformation without loose wear particles at the intermediate region, and (3) formation of fine oxide particles at the gross slip region. The critical slip amplitude of fretting is the boundary between (2) and (3). The boundary slip amplitude depends on normal load. The wear rate increases and saturates with increasing slip amplitude. But it is constant by considering the critical amplitude. The role of oxide particles are discussed. Three different actions are noted: accelerating wear, preventing wear and insignificant effect. The oxide shows two opposing effect depends on normal load and slip amplitude. This is related to the removal rate from the interface (abrasive action) and compaction rate at the interface to form a protective layer. The effect of oxidation is significant to determine the wear and friction. The diffusion of oxygen is restricted at the small amplitude. As a result, crack formation at the boundary is a predominant damage, related to fretting fatigue damage.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.208.2-212
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• 1997

In a model based friction comensation for a frictional system,the performance of the system is inflenceed by the selection of the friction model. Especially, when a real plant have dynamic friction characteritics, the compensation of friction with a static friction model may deteriorate the perfomance. For the system we constlucted an adaptiv parameter estimation and friction compensation with a newly introduced dynamic friction model proposed by Canudas et.[1]. The model depicts varios frictional phenomena,such as Stibeck effect,frictional memory, Stick-slip motion. Parmeter identification algorithm are followed conventional RLSM adaptive rule. The stability for the closed system was proved by the Lyapunov stability. The result say that if a real system have dynamic friction property,the friction compensation with the dynamic friction model will improve the perfomance moreover static friction model based compensation may lead to the system unstable.