2001 Fiscal Year Final Research Report Summary
Study on the Dynamic Thermal Contact Resistance and Its Evaluation
| Project/Area Number |
12650195
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Yokohama National University |
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Principal Investigator |
TORII Kahoru Yokohama National University, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (00017998)
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| Co-Investigator(Kenkyū-buntansha) |
NISHINO Koichi Yokohama National University, Faculty of Engineering, Associate Professor, 大学院・工学研究院, 助教授 (90192690)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Heat Conduction / Thermal Contact Resistance / Dynamic Thermal Resistance / Transient Method / Numerical Analysis / Constriction Resistance / Rarefied Gas Effect |
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| Research Abstract |
This study aims at understanding the physical mechanisms of dynamic thermal contact resistance (TCR) of cylindrical surfaces in rolling contact. As a first step to clarifying this complex phenomenon, the TCR of statically-contacting cylindrical surfaces has been investigated in detail. A transient method for the evaluation of TCR is developed with a view to applying it to the dynamic case. The technique is used to estimate the value of TCR for rollers made of either steel (S45C) or aluminum alloy (A6061). A series of experimental and computation evaluations is made for TCR of contacting rolls, whose dimension is 60 mm in diameter and 180 in length, under the loading conditions of 10-120 kgf(98-1 1 80 N). The conclusions gained by the present study are summarized as follows :
(1) The total TCR measured and estimated decreases with load applied to the rollers.
(2) Microscopic constriction resistance at a contact line becomes negligible for the load larger than 20 kgf under the present cond
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itions. Instead, macroscopic constriction resistance due to the heat flow's converging to the contact line becomes dominant in overall TCR.
(3) This macroscopic constriction resistance is dependent on the width of the contact line. The width is estimated to be about 1.4-2.4 mes, the value given by the Hertz theory of elastic contact. This discrepancy is likely due to the roughness present on the surfaces.
(4) The conduction heat transfer through the air present between the contacting surfaces has an important contribution to the overall heat transfer. The consideration of the rarefied gas effect is also important for very thin air layer near the contact line
(5) The effect of heat capacity of the contact resistance layer responsible for the microscopic constriction resistance can be neglected.
This suggests that the overall dynamic TCR of cylindrical surfaces in rolling contact may be evaluated from the static microscopic TCR plus the dynamic macroscopic TCR, the latter can be predicted numerically by conventional computational methods. Less
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Research Products
(2 results)
