Internal Friction in Solids. I. Theory of Internal Friction in Reeds

TLDR

In a vibrating reed, opposite sides undergo dilations of opposite signs, so heating one side cools the other; at low frequencies vibrations are isothermal, at high frequencies adiabatic, and at intermediate frequencies they are hybrid with internal friction. The study calculates the internal friction of this hybrid vibration purely from thermodynamic principles. The authors derive the internal friction analytically using thermodynamic relations without empirical parameters. The predicted internal friction for the hybrid vibration is larger in magnitude than that from all other causes.

Abstract

In a vibrating reed opposite sides have dilations of opposite signs. Thus when one side is heated the other is cooled. At low frequencies the vibrations are isothermal. At high frequencies they are adiabatic. At intermediate frequencies they are of a hybrid type accompanied by internal friction. In this paper this internal friction is calculated solely from thermodynamical considerations. It is predicted that the internal friction associated with this hybrid type of vibration is of a larger order of magnitude than that due to all other causes.