• Title/Summary/Keyword: Disk-Pad Brake

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Friction and Wear Characteristics of Automotive Friction Materials Containing Different Relative Amounts of Solid Lubricants(Graphite, MoS2and 2S3) (고체윤활제(Graphite, MoS2, Sb2S3)의 상대량에 따른 마찰재의 마찰 및 마모특성에 관한 연구)

  • Choi, Nak-Cheon;Jang, Ho
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1999.11a
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    • pp.219-224
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    • 1999
  • The effects of solid lubricants on wear and friction characteristics of friction materials were studied using a pad-on-disk type friction tester. Friction materials with ten formulations containing different relative amounts of solid lubricants(graphite, MoS2and Sb2S3) were investigated. Results of this work showed that each formulation with different relative amounts of the lubricants had unique friction characteristics. At low brake temperatures, friction materials containing rich graphite showed a small amount of μ change during sliding. At elevated temperatures, on the other hand, friction materials with rich Sb2S3and graphite showed smaller μ changes suggesting complementary lubrication of Sb2S3and graphite during sliding. However, the friction materials with rich Sb2S3showed a large amount of wear.

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The effects of damping on the limit cycle of a 2-dof friction induced self-oscillation system (마찰 기인 2 자유도계 시스템의 자려진동에 대한 댐핑의 영향)

  • 조용구;신기흥;오재웅
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.89-96
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    • 2002
  • A two-degree of freedom model is suggested to understand the basic dynamical behaviors of the interaction between two masses of the friction induced vibration system. The two masses may be considered as the pad and the disk of the brake, The phase space analysis is performed to understand complicated dynamics of the non-linear model. Attractors in the phase space are examined for various conditions of the parameters of the model especially by emphasizing on the damping parameters. In certain conditions, the attractor becomes a limit cycle showing the stick-slip phenomena. In this paper, not only the existence of the limit cycle but also the size of the limit cycle is examined to demonstrate the non-linear dynamics that leads the unstable state. For the two different cases of the system frequency ((1)two masses with same natural frequencies, (2) with different natural frequencies), the propensity of limit cycle is discussed in detail. The results show an important fact that it may make the system worse when too much damping is present in the only one part of the masses.

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The Effect of Metal Fibers on the Tribology of Automotive Friction Materials (마찰재에 함유된 금속섬유와 마찰 특성의 연관관계)

  • Ko, Kil-Ju;Cho, Min-Hyung;Jang, Ho
    • Tribology and Lubricants
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    • v.17 no.4
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    • pp.267-275
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    • 2001
  • Friction and wear properties of brake friction materials containing different metal fibers (Al, Cu or Steel fibers) were investigated. Based on a simple experimental formulation, friction materials with the same amount of metal fibers were tested using a pad-on-disk type friction tester. Two different materials (gray cast iron and aluminum metal matrix composite (MMC)) were used for disks rubbing against the friction materials. Results front ambient temperature tests revealed that the friction material containing Cu fibers sliding against gray cast iron disk showed a distinct negative μ-v (friction coefficient vs. sliding velocity) relation implying possible stick-slip generation at low speeds. The negative μ- v relation was not observed when the Cu-containing friction materials were rubbed against the Al-MMC counter surface. Elevated temperature tests showed that the friction level and the intensity of friction force oscillation were strongly affected by the thermal conductivity and melting temperature of metallic ingredients of the friction couple. Friction materials slid against cast iron disks exhibited higher friction coefficients than Al-MMC (metal matrix composite) 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 that steel fibers were not compatible with Al-MMC disks showing severe material transfer and erratic friction behavior during sliding at elevated temperatures.

Development of a Wheel Slip Control System for Vehicle Cornering Stability (차량 선회 안정성을 위한 휠 슬립 제어시스템 개발)

  • Hong, Dae-Gun;Huh, Kun-Soo;Hwang, In-Yong;SunWoo, Myoung-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.4
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    • pp.174-180
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    • 2006
  • 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 braking control systems. In order to achieve the superior braking performance through the wheel slip control, 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, stability enhancement, etc. In this paper, a wheel slip control system is developed for maintaining the vehicle stability based on the braking monitor, wheel slip controller and optimal target slip assignment algorithm. The braking monitor estimates the tire braking force, lateral tire force and brake disk-pad friction coefficient utilizing the extended Kalman filter. The wheel slip controller is designed based on the sliding mode control method. The target slip assignment algorithm is proposed to maintain the vehicle stability based on the direct yaw moment controller and fuzzy logic. The performance of the proposed wheel slip control system is verified in simulations and demonstrates the effectiveness of the wheel slip control in various road conditions.