Internal friction in a QE22 hybrid composite

This paper describes the influence of thermal loading on the damping behaviour of a composite with QE22 matrix reinforced with short Saffil fibres and SiC particles. The composite was prepared by squeeze casting. The logarithmic decrement was measured after a thermal cycle between room temperature and an upper temperature that varied within the range from 40 to 400 °C. A region of strain amplitude independent damping at low strains is followed by a region with amplitude dependent damping at higher amplitude strains. The values of the logarithmic decrement in the strain amplitude dependent region depend very sensitively on the upper temperature of the cycle. The experimental data can be explained considering creation of new dislocations during thermal cycling and recovery processes at higher upper temperatures.