Understanding Service Factor, Thermal Models, and Overloads

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.

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Continuum modeling perspectives of non-Fourier heat conduction in biological systems

Journal of Non-Equilibrium Thermodynamics ◽

10.1515/jnet-2021-0016 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ákos Sudár ◽

Gergely Futaki ◽

Róbert Kovács

Keyword(s):

Biological Systems ◽

Phase Lag ◽

Dual Phase ◽

Continuum Modeling ◽

Biological Origin ◽

Ultrasound Surgery ◽

Thermal Models ◽

Wide Range ◽

Fourier Heat Conduction ◽

The Continuum

Abstract The thermal modeling of biological systems is increasingly important in the development of more advanced and more precise techniques such as ultrasound surgery. One of the primary barriers is the complexity of biological materials: the geometrical, structural, and material properties vary in a wide range. In the present paper, we focus on the continuum modeling of heterogeneous materials of biological origin. There are numerous examples in the literature for non-Fourier thermal models. However, as we realized, they are associated with a few common misconceptions. Therefore, we first aim to clarify the basic concepts of non-Fourier thermal models. These concepts are demonstrated by revisiting two experiments from the literature in which the Cattaneo–Vernotte and the dual phase lag models are utilized. Our investigation revealed that these non-Fourier models are based on misinterpretations of the measured data, and the seeming deviation from Fourier’s law originates from the source terms and boundary conditions.

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Accretion of a large LL parent planetesimal from a recently formed chondrule population

Science Advances ◽

10.1126/sciadv.aay8641 ◽

2020 ◽

Vol 6 (16) ◽

pp. eaay8641

Author(s):

Graham H. Edwards ◽

Terrence Blackburn

Keyword(s):

Body Size ◽

Size Distribution ◽

Total Duration ◽

Parent Body ◽

Ordinary Chondrite ◽

Minimum Size ◽

Thermal Models ◽

Early Stages ◽

Chondritic Meteorites ◽

Chondrule Formation

Chondritic meteorites, derived from asteroidal parent bodies and composed of millimeter-sized chondrules, record the early stages of planetary assembly. Yet, the initial planetesimal size distribution and the duration of delay, if any, between chondrule formation and chondrite parent body accretion remain disputed. We use Pb-phosphate thermochronology with planetesimal-scale thermal models to constrain the minimum size of the LL ordinary chondrite parent body and its initial allotment of heat-producing 26Al. Bulk phosphate 207Pb/206Pb dates of LL chondrites record a total duration of cooling ≥75 Ma, with an isothermal interior that cools over ≥30 Ma. Since the duration of conductive cooling scales with parent body size, these data require a ≥150-km radius parent body and a range of bulk initial 26Al/27Al consistent with the initial 26Al/27Al ratios of constituent LL chondrules. The concordance suggests that rapid accretion of a large LL parent asteroid occurred shortly after a major chondrule-forming episode.

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