Thermal Characteristics of a Wet Clutch

1999 ◽  
Vol 121 (3) ◽  
pp. 610-617 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Thermal Effects ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Friction Material ◽  
Solution Technique ◽  
Governing Equations ◽  
Viscous Heat ◽  
Wet Clutch ◽  
Engagement Process ◽  
Full Consideration

A comprehensive formulation of the governing equations, boundary conditions, and numerical solution technique is presented for modeling the thermal aspects of the engagement process in a wet clutch. The thermal model includes full consideration of the viscous heat dissipation in the fluid as well as heat transfer into the separator, friction material, and the core disk. Roughness, waviness, deformability and permeability of the friction material are taken into account. It is shown that very large temperatures develop in the fluid during the engagement process which takes place on the time scale of one second. It is also shown that thermal effects influence the engagement time and the torque behavior of a clutch and should be included in the analytical studies.

Three-Dimensional Thermohydrodynamic Analysis of a Wet Clutch With Consideration of Grooved Friction Surfaces

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari ◽  
Rikard Maki
Keyword(s):  
Heat Dissipation ◽  
Three Dimensional ◽  
Groove Depth ◽  
Friction Material ◽  
Temperature Fields ◽  
Torque Response ◽  
Viscous Heat ◽  
Wet Clutch ◽  
Engagement Process ◽  
Energy Equations

A model is developed to investigate the effect of radial grooves and waffle-shape grooves on the performance of a wet clutch. Three-dimensional formulation of the governing equations, boundary conditions, and numerical solution scheme are presented for modeling the thermal aspects of the engagement process in a wet clutch. The thermal model includes full consideration of the viscous heat dissipation in the fluid as well as heat transfer into the separator, the friction material, and the core disk. The convective terms in the energy equations for the oil as well as the heat conduction equations in the bounding solids are properly formulated to determine the temperature fields corresponding to the domains between grooves. Roughness, centrifugal force, deformability, and permeability of the friction material with grooves are taken into account. The effects of groove geometry such as groove depth, grooved area, and number of grooves on the engagement characteristic of a wet clutch are investigated. It is also shown that the thermal effects in a wet clutch influence the engagement time and the torque response and should be included in the analytical studies.

On the Formation of Hot Spots in Wet Clutch Systems

2001 ◽  
Vol 124 (2) ◽  
pp. 336-345 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Hot Spots ◽  
Friction Material ◽  
Mechanical Seal ◽  
Comprehensive Model ◽  
Governing Equations ◽  
Thermoelastic Instability ◽  
Wet Clutch ◽  
Special Case

A comprehensive model is developed for analyzing the onset of thermoelastic instability in a wet clutch. For this purpose, appropriate governing equations are derived that take into account the porosity and deformability of the friction material. The effect of the thickness of the separator disk and that of the friction material are also included. The model is general and can be used to describe TEI in a variety of other systems such as in a mechanical seal, as a special case. A series of simulations are presented that predict the thermoelastic behavior of a wet clutch from an instability viewpoint.

Parametric analysis of wear factors of a wet clutch friction material with different groove patterns

2017 ◽  
Vol 231 (8) ◽  
pp. 1056-1067 ◽  
Author(s):  
M Li ◽  
MM Khonsari ◽  
DMC McCarthy ◽  
Joakim Lundin
Keyword(s):  
Temperature Field ◽  
Material Properties ◽  
Parametric Analysis ◽  
Wear Test ◽  
Friction Material ◽  
Asperity Contact ◽  
Wet Clutch ◽  
Engagement Process ◽  
Insight Into ◽  
Friction Lining

The experimentally observed, two-stage wear in the wet clutch friction material is directly related to temperature and engagement load. To gain insight into the durability of the friction lining, an extensive parametric analysis of the factors is performed that takes into account different groove patterns (waffle shape, radial, and spiral), internal structure and material properties. The temperature field is predicted using a thermohydrodynamic analysis with the consideration of the asperity contact stress during the engagement process. The results should be useful to facilitate the industrial design of friction lining by avoiding costly wear test.

scholarly journals Effects of operating and material parameters on the thermal characteristics of a wet clutch

2021 ◽  
Vol 13 (7) ◽  
pp. 168781402110341
Author(s):  
Zhigang Zhang ◽  
Ling Zou ◽  
Hang Liu ◽  
Yonglong Chen ◽  
Benzhu Zhang
Keyword(s):  
Heat Flux ◽  
Applied Pressure ◽  
Thermal Characteristics ◽  
Thermal Models ◽  
Material Parameters ◽  
Heat Transfer Theory ◽  
Friction Disk ◽  
Viscous Shear ◽  
Wet Clutch ◽  
Transient Thermal

Based on the frictional mechanism of a wet clutch, frictional models of wet clutch engagement were established using the modified Reynolds equation and the elastic contact model between frictional pairs. Then, the heat flux models for the viscous shear and asperity friction were built, and the two-dimensional transient thermal models for the separator plate, friction disk, and ATF heat convection model were deduced based on the heat transfer theory and conservation law of energy. Finally, the Runge–Kutta numerical method was used to solve the frictional and thermal models. The average temperature of the separator plate, friction disk, and ATF were calculated. The effects of operating and material parameters, such as applied pressure, initial angular velocity, friction lining permeability, surface combined roughness RMS, equivalent elastic modulus, and ATF flow, on the thermal characteristics of friction pairs and ATF during engagement, were studied. The simulation results show that the temperature characteristics of the separator plate, friction disk, and ATF depend mainly on the viscous shear and asperity friction heat flux, and that the operating and material parameters of the wet clutch also have significant impacts on the overall variation trend of the thermal characteristics of the separator plate, friction disk, and ATF.

scholarly journals Effect of perspired moisture and material properties on evaporative cooling and thermal protection of the clothed human body exposed to radiant heat

2018 ◽  
Vol 89 (18) ◽  
pp. 3663-3676 ◽  
Author(s):  
Manhao Guan ◽  
Agnes Psikuta ◽  
Martin Camenzind ◽  
Jun Li ◽  
Sumit Mandal ◽  
...  
Keyword(s):  
Human Body ◽  
Material Properties ◽  
Heat Dissipation ◽  
Thermal Protection ◽  
Evaporative Cooling ◽  
Thermal Characteristics ◽  
Radiant Heat ◽  
Physiological Effect ◽  
Heat Gain ◽  
Active Liquid

Perspired moisture plays a crucial role in the thermal physiology and protection of the human body wearing thermal protective clothing. Until now, the role of continuous sweating on heat transfer, when simultaneously considering internal and external heat sources, has not been well-investigated. To bridge this gap, a sweating torso manikin with 12 thermal protective fabric systems and a radiant heat panel were applied to mimic firefighting. The results demonstrated how the effect of radiant heat on heat dissipation interacted with amount of perspired moisture and material properties. A dual effect of perspired moisture was demonstrated. For hydrophilic materials, sweating induced evaporative cooling but also increased radiant heat gain. For hydrophilic station uniforms, the increment of radiant heat gain due to perspired moisture was about 11% of the increase of heat dissipation. On the other hand, perspired moisture can increase evaporative cooling and decrease radiant heat gain for hydrophobic materials. In addition to fabric thermal resistance ( Rct) and evaporative resistance ( Ret), material hydrophilicity and hydrophobicity, emissivity and thickness are important when assessing metabolic heat dissipation and radiant heat gain with profuse sweating under radiant heat. The results provide experimental evidence that Rct and Ret, the general indicators of the clothing thermo-physiological effect, have limitations in characterizing thermal comfort and heat strain during active liquid sweating in radiant heat. This paper offers a more complete insight into clothing thermal characteristics and human thermal behaviors under radiant heat, contributing to the accurate evaluation of thermal stress for occupational and general individuals.

Modeling and experimental research on engaging characteristics of wet clutch

2019 ◽  
Vol 71 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Yanzhong Wang ◽  
Yuan Li ◽  
Yang Liu ◽  
Wei Zhang
Keyword(s):  
Contact Surface ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Lubricating Oil ◽  
Centrifugal Effect ◽  
Element Analysis ◽  
Content Type ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Engagement Process

PurposeTo gain in-depth understandings of engaging characteristics, the purpose of this paper is to improve the model of wet clutches to predict the transmitted torque during the engagement process.Design/methodology/approachThe model of wet clutch during the engagement process took main factors into account, such as the centrifugal effect of lubricant, permeability of friction material, slippage factor of lubricant on contact surface and roughness of contact surface. Reynolds’ equation was derived to describe the hydrodynamic lubrication characteristics of lubricant film between the friction plate and the separated plate, and an elastic-plastic model of the rough surfaces contact based on the finite element analysis was used to indicate the loading force and friction torque of the contact surface.FindingsThe dynamic characteristics of wet clutch engagement time, relative speed, hydrodynamic lubrication of lubricating oil, rough surface contact load capacity and transfer torque can be obtained by the wet clutch engagement model. And the influence of the groove shape and depth on the engaging characteristics is also analyzed.Originality/valueThe mathematical model of the wet clutch during the engagement process can be used to predict the engaging characteristics of the wet clutch which could be useful to the design of the wet clutch.

Thermal Effects on the Vibration of Functionally Graded Deep Beams with Porosity

2017 ◽  
Vol 09 (05) ◽  
pp. 1750076 ◽  
Author(s):  
Şeref Doğuşcan Akbaş
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Thermal Effects ◽  
Functionally Graded ◽  
Deep Beam ◽  
Material Distribution ◽  
Governing Equations ◽  
Temperature Dependent ◽  
Deep Beams

The purpose of this study is to investigate the thermal effects on the free vibration of functionally graded (FG) porous deep beams. Mechanical properties of the FG deep beam are temperature-dependent and vary across the height direction with different porosity models. The governing equations problem is obtained by using the Hamilton’s principle. In the solution of the problem, plane piecewise solid continua model and finite element method are used. The effects of porosity parameters, material distribution, porosity models and temperature rising on the vibration characteristics are presented and discussed with porosity effects for FG deep beams.

Thermal Effects Due to Surface Films in Sliding Contact

1994 ◽  
Vol 116 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Brian Vick ◽  
L. P. Golan ◽  
M. J. Furey
Keyword(s):  
Thermal Properties ◽  
Temperature Rise ◽  
Thermal Effects ◽  
Three Dimensional ◽  
Sliding Contact ◽  
Frictional Heat ◽  
Solution Technique ◽  
Surface Films ◽  
Thermal Coupling ◽  
Efficient Manner

The present work examines theoretically the influence of surface coatings on the temperatures produced by friction due to sliding contact. A generalized thermal model is developed which incorporates three-dimensional, transient heat transfer between layered media with thermal coupling at multiple, interacting contact patches. A solution technique based on a variation of the boundary element method is developed and utilized. The method allows for the solution of the distribution of frictional heat and the resulting temperature rise in an accurate yet numerically efficient manner. Results are presented showing the influence of film thickness, thermal properties, velocity, and contact area on the division of heat and surface temperature rise. The results show that a film with thermal properties different than those of the substrate can have a pronounced effect on the predicted temperature rise.

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