THERMAL SCIENCE

International Scientific Journal

THERMAL EFFECT ON THE THERMOMECHANICAL BEHAVIOR OF CONTACTS IN A TRAVELING WAVE TUBE

ABSTRACT
A new elasto-plastic study of the contact between the helix and the rods of the delay line of Traveling Waves Tubes (TWT) was realized. Our study is focused on the analysis of the hot lines shrinking phenomenon. In the studied case, unlike brazed configuration, the contact areas are not perfect, resulting in a diminution of the heat transfer process. In order to maximize the contact area and to homogenize the contact pressure, a soft thermal conductive material is coated on the helix: copper was chosen for this study. In the present work, an analytical model is used to identify the properties of the copper coating at a given temperature. We focused on the mechanical properties in order to improve the assembly process with a better numerical study. Experimental method have been made to validate the proposed model. The first comparison results seem to indicate that the model represents the reality with a good agreement. It is very clearly shown that the temperature decreases the mechanical properties. (Young’s modulus, yield strength, tensile strength…). And the thickness of the coating increases the contact area. This last point is less important at room temperature (6% of increase) than at 140°C (22%).
KEYWORDS
PAPER SUBMITTED: 2014-12-16
PAPER REVISED: 2015-01-03
PAPER ACCEPTED: 2015-01-13
PUBLISHED ONLINE: 2015-01-24
DOI REFERENCE: https://doi.org/10.2298/TSCI141216010C
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THERMAL SCIENCE YEAR 2016, VOLUME 20, ISSUE 6, PAGES [1983 - 1990]
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© 2019 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence