Shrink fit between ceramic and metal with the use of a hybrid shrink fitter (Calculations of distributions of contact pressures)

The shrink-fitted assemblies between a ceramic shaft and a metal ring with a hybrid shrink fitter which contains liquid have been analyzed as a two-dimensional elastic problem. Water was used as the liquid contained in the hybrid shrink fitters because its thermal expansion at elevated temperature has already been investigated in detail. Calculations were performed for the temperature range 20°C up to 600°C. Materials were Al2O3 and Si3N4 for the shafts, SUS403 for the metal ring and SUS304 for the casing of the hybrid shrink fitters. Three different shapes of hybrid shrink fitters were used for the distribution of the contact pressures. The mean contact pressures of the assemblies depended greatly upon the internal pressures of the shrink fitters. The mean contact pressures decreased with temperature from 20°C up to a certain degree of temperature, and at higher temperatures, the mean contact pressures increased with temperature. These calculated results were quantitatively in agreement with the experimental results in a previous paper, although the contained liquids were different from each other. The equivalent stresses of the casing were high when the casing contained only water. Then, an amount of Si3N4 powder was mixed with the contained water to decrease the equivalent stresses of the casing. Longevities of the assemblies with the hybrid shrink fitters were discussed.