Research on the solution method for thermal contact conductance between circular-arc contact surfaces based on fractal theory

摘要

A thermal contact conductance (TCC) prediction model between circular-arc rough contact surfaces is established. The self-similarity and continuity of rough surfaces are characterised by using the Weierstrass-Mandelbrot (W-M) function. Then, the model of contact mechanics is established. In addition, the contact force and deformation of the contact surfaces at different states are calculated by considering the three deformation processes of elastic, elastic-plastic, and complete plastic. Thus, a numerical method for calculating the predicted TCC is provided. The global contact stress and TCC distribution caused by the change in the contact azimuth angle are analysed. Simultaneously, the fractal parameters of the circular-arc contact surfaces and the TCC calculation during the experiment are introduced. The effects of different materials, external contact temperature, contact-surface roughness and contact pressure on the TCC are analysed. The experimental results agree well with the simulation calculations, which validate the accuracy of the simulation results. We find that a temperature waterfall phenomenon occurs between the circular-arc contact surfaces. As the external contact temperature and contact pressure increase, the 'softening' phenomenon of asperities occurs, resulting in an increase in the TCC. Meanwhile, the TCC decreases with the increase in the surface roughness, and it is cross-impacted by the material properties. This study provides a basis for TCC prediction in engineering practice. (C) 2019 Elsevier Ltd. All rights reserved.