• Title/Summary/Keyword: Contact frictional heat

Search Result 52, Processing Time 0.024 seconds

Analyses of Influence of Frictional Heat on the Contact Stress of High-speed Micro-gears

  • Kim, Cheol;Kim, Hyeong-Seok
    • Composites Research
    • /
    • v.28 no.4
    • /
    • pp.244-248
    • /
    • 2015
  • When a small gear rotates at a very high speed over 40,000 rpm, frictional heat is generated on the gear surfaces. Thermal deformations and stresses arising from frictional heat may lower the efficiency and fatigue life of the high-speed gear. Especially, such frictional heat has much stronger effects on the performance of millimeter-sized high-speed gears used for surgical and dental hand-pieces, due to a small surface area. An analytical equation was derived to calculate frictional temperature on a mating gear surface and conduction heat transfer analysis was performed. Thermal deformation and contact stresses were then calculated using FEM for gears used for medical hand-pieces. The contact stresses of the meshed gear and pinion increase by 19.4% and 16.4%, respectively, when the frictional thermal deformations are considered.

Thermoelastic Contact Analysis of Drums Brakes by Finite Element Method (유한요소법에 의한 드럼 브레이크의 열탄성 접촉해석)

  • 구병춘;서정원
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.9 no.3
    • /
    • pp.173-180
    • /
    • 2001
  • In the case of axisymmetric thermal analysis of drum brakes, the distribution of frictional heat produced on the interface and temperature difference between mating frictional faces are very interesting problems to computational researchers. In the first part, the influence of the s-cam load angles and elastic modulus of the pad on the contact pressure distribution between pad and drum was checked by a three dimensional model. In the second part heat conduction from the interface to the pad and the drum was modeled by using a thin interface element, so artificial division of the generated frictional heat between pad and drum is not necessary. Temperature difference between mating frictional faces is successfully modeled by using the interface element. The influence of some parameters on the thermal distribution is checked. The analysis was performed by ABAQUS/Standard code.

  • PDF

Frictional Heat Generation in Wet Clutch Engagement according to Groove Pattern on Clutch Pad (습식클러치 마찰재의 체결 거동에 의한 마찰열 해석)

  • Kim, HaeYong;Jang, Siyoul;Kim, WooJung
    • Tribology and Lubricants
    • /
    • v.30 no.5
    • /
    • pp.265-270
    • /
    • 2014
  • Frictional heat greatly influences the friction behaviors during clutch engagement. Therefore, the engagement of a wet or dry clutch is frequently not under control by the frictional heat. In a wet clutch, the frictional temperature also specially needs to be controlled, and in many cases, the clutch material is selected to prevent a temperature rise from the friction between friction pad and separator. However, only the selection of the clutch material cannot ensure sufficient control of the temperature rise by the friction. The groove pattern on a friction pad is designed for more flow rates of transmission fluid between the contact gap of clutch pad and separator for the cooling effect. In this work, grove patterns are designed for more flow rates out of the contact gap between friction pad and separator plate. Selected groove design shows the improvement flow rates of transmission fluid through both inner and outer radius, where most of the transmission fluid flows through the outer radius when the clutch is engaged due to the centrifugal force in conventional wet clutch groove. Several comparisons of the amounts of frictional heat generated on clutch pads are made in order to verify the decrease of the temperature rise according to the flow rates along the groove patterns.

Thermo-elastic Frictional Contact Analysis of Airplane Brakes (항공기 제동장치의 열탄성 마찰 접촉 해석)

  • Lee, Chang-Won;Choi, Yong-Gie;Kwak, Byung-Man
    • Proceedings of the KSME Conference
    • /
    • 2001.06a
    • /
    • pp.889-894
    • /
    • 2001
  • A three dimensional transient thermo-elastic frictional contact analysis of airplane brakes is performed. The velocity history of the airplane during braking is calculated from energy conservation law. ABAQUS code is used in the analysis, and user subroutines supported in the ABAQUS are coded to calculate the frictional heat generation between pads and linings attached to back/pressure plate and rotor, respectively. Numerical results are compared with experimental ones.

  • PDF

A Study for Estimation of the Surface Temperature Rise Using the FVM and Semi-Infinite Solid Analysis (FVM과 반무한체 해석을 이용한 표면온도예측에 관한 연구)

  • 김태완;이상돈;조용주
    • Tribology and Lubricants
    • /
    • v.18 no.6
    • /
    • pp.389-395
    • /
    • 2002
  • The surface temperature at the interface of bodies in a sliding contact is one of the most important factors influencing the behavior of machine components. The calculation of the surface temperature at a sliding contact interface has been an interesting and important subject for tribologist. Temperature analyses were usually performed under the consideration contacted two bodies as semi-infinite. But the analysis was difficulty in being applied to finite body and considering the boundary condition. In this study, contact temperature rise of two finite bodies and surfaces due to frictional heating under the rectangular and the circular sliding contact is calculated. Heat partition factor is calculated using semi-infinite solid analysis and the temperature of the finite bodies is calculated using FVM. It will be shown that Most frictional heat in the fore part of contact region for sliding direction is conducted into body that has a moving heat source and the site of the maximum temperature rise moves to the opposite direction of sliding during sliding.

A Method to Simulate Frictional Heating at Defects in Ultrasonic Infrared Thermography

  • Choi, Wonjae;Choi, Manyong;Park, Jeonghak
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.35 no.6
    • /
    • pp.407-413
    • /
    • 2015
  • Ultrasonic infrared thermography is an active thermography methods. In this method, mechanical energy is introduced to a structure, it is converted into heat energy at the defects, and an infrared camera detects the heat for inspection. The heat generation mechanisms are dependent on many factors such as structure characteristics, defect type, excitation method and contact condition, which make it difficult to predict heat distribution in ultrasonic infrared thermography. In this paper, a method to simulate frictional heating, known to be one of the main heat generation mechanisms at the closed defects in metal structures, is proposed for ultrasonic infrared thermography. This method uses linear vibration analysis results without considering the contact boundary condition at the defect so that it is intuitive and simple to implement. Its advantages and disadvantages are also discussed. The simulation results show good agreement with the modal analysis and experiment result.

Temperature Rise Analysis of Sliding Contact Surfaces in Lubrication Considering Elastic Deformation (탄성변형을 고려한 윤활 상태에서 거친 표면의 미끄럼 접촉온도 해석)

  • Cho Yong-Joo;Kim Byoung-Sun;Lee Sang-Don
    • Tribology and Lubricants
    • /
    • v.22 no.3
    • /
    • pp.137-143
    • /
    • 2006
  • The sliding contact interface of machine components such as bearings, gears frequently operates in lubrication at the inception of sliding failure under high loads, speed and slip. The surface temperature at the interface of bodies in a sliding contact is one of the most important factors influencing the behavior of machine components. Most surface failure in sliding contact region result from frictional heat generation. However, it is difficult to measure temperature rise experimentally. So the calculation of the surface temperature at a sliding contact interface has long been an interesting and important subject for tribologist. The surface temperature rise is related in contact pressure, sliding speed, material properties and lubrication thickness. Though roughness, load, ect all of the condition, are same, film thickness varies with velocity. In this study, surface temperature rise due to frictional heating in lubrication is calculated with various velocities. Surface film shearing and dry solid asperity contact are used to simulate the change of frictional heat in lubricated contact

A Study on Convergence Contact Behavior of Friction Heat and Pad on Disk Brake (디스크 브레이크에서 마찰열과 패드에 작용하는 융합 접촉거동에 관한 연구)

  • Han, Seung-Chul;Lee, Bong-Gu
    • Journal of the Korea Convergence Society
    • /
    • v.9 no.1
    • /
    • pp.283-289
    • /
    • 2018
  • In automotive disc brake systems, frictional heat is not uniformly dispersed for reasons such as heat flux and thermal deformation. The thermoelastic deformation due to the frictional heat affects the contact pressure distribution and the contact load may be concentrated on the contact portion on the the disc brake surface, resulting in thermoelastic instability. In this study, thermal analysis and thermal deformation analysis considering the contact between disk and pad occurred during braking through 3D axial symmetry model with reference to the experimental equation and Kao's analysis method of contact pressure of disk and pad. ANSYS is used to analyze the thermal and elastic instability problems occurring at the contact surface between the disk and the pad, considering both the thermal and mechanical loads. A 3D axisymmetric model with direct contact between the disk and the pad was constructed to more accurately observe the thermal behavior of the disk by observing the frictional surface temperature, thermal deformation and contact thermal stress of the disk.

The Thermal Analysis of Brake Disc using the Solid Model and 2D Coupled Model (솔리드모델과 2D 연성모델을 사용한 브레이크 디스크의 열해석)

  • 강상욱;김창진;이대희;김흥섭
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.11 no.6
    • /
    • pp.93-100
    • /
    • 2003
  • This paper describes the thermoelastic instability arising from friction heat generation in braking and proposes the finite element methods to predict the variation of temperature and thermal deformation. In a conventional disc brake analysis, heat generation is only related with wheel speed and friction material and the interface pressure between disc and pad is assumed constant. But under dynamic braking conditions, the frictional heat causes the thermoelastic distortion that leads to more concentrated contact pressure distribution and hence more and more non-uniform temperature. In this paper, to complete the solution of the thermomechanically coupled problem, the linear relation model between pressure and temperature is proposed and demonstrated in examples of a simple two dimensional contact problem. And the two dimensional model has been extended to an annular three dimensional disc model in order to consider more realistic geometry and to provide a more accurate critical speed for automotive brake systems.