Effects of surface morphology on thermal contact resistance

Abstract

The thermal contact resistance is common in aerospace industry, nuclear reactors and electronic equipments. The work addresses a new scheme for determining the thermal contact resistance between a smooth surface of a film and a rough surface of a metal specimen. The finite element method was used as a tool to explore the surface morphology effect on the thermal contact resistance while the temperature of the contact surface was determined by a regression method. According to the results developed, the temperature on the contact surfaces linearly drops with the increasing average height of surface roughness and nonlinearly drops with the increasing ratio between non-contact area and nominal contact area. On the other hand, the thermal contact resistance increases linearly with increases in the average height of the surface roughness. What's more, the thermal contact resistance increases in a non-linear manner as the ratio of the non-contact area to the nominal contact area is increasing.

Impact of Surface Roughness on Pantograph-Catenary Current Collection Quality

“…After obtaining the corresponding weight coefficients of each evaluation index, the comprehensive evaluation equation of pantograph-catenary current collection characteristics is established by comprehensively considering the influence of roughness on Pantograph-catenary contact resistance, current carrying efficiency, current collection stability and friction coefficient, as shown in formula (10).…”

“…Therefore, within the experimental range, the Ra value that maximizes F(Ra ) is the optimal roughness value. The weight coefficient and functional relationship of each evaluation index are substituted into formula (10), and the comprehensive evaluation curve drawn under different roughness conditions and the corresponding comprehensive evaluation values calculated through experiments are shown in FIGURE 11. According to the calculation method of derivative in mathematics (the calculation formula is shown in formula (11)), the roughness parameter Ra =5.86 μm, F(Ra) reaches the maximum value, that is, the pantograph-catenary current collection condition is the best at this time.…”

Thermo-Mechanical Behavior of Fiber Reinforced MMC

“…The matrix-partition method was suggested by extending the existing unmixed-mixed scheme. The deformation states in the matrix phase can be represented with a set of mechanical variables for the respective parts of the partitioned matrix [3][4][5][6][7][8].…”