Thermoelastic Damping in Materials With a Complex Coefficient of Thermal Expansion

Abstract

The effect of a complex coefficient of thermal expansion upon the thermoelastic relaxation mechanism is analyzed. A phase angle in the thermal expansion has the effect of generating a very broad band of mechanical damping, in addition to the peak usually observed. Phase angles in the thermal expansion have been observed in several polymers, and they may be generated in composite materials in which one or more phases is viscoelastic. However the resulting enhancement of the overall damping of the composite is modest, unless new materials can be found with very high relaxation strength or with a large intrinsic phase angle in the expansion.