Internal friction: Some considerations of the frequency response of rocks and other metallic and non-metallic materials

Abstract

Although several workers, including the authors, have shown that the attenuation exponent in rocks tends to increase linearly with frequency, such behaviour is not general for all materials: metals, in particular, project several internal friction peaks over a spectrum of frequencies, each peak being ascribed to a certain physical process operating in the material. This article reviews in a simple manner some basic concepts behind the frequency response of various materials since a general knowledge of the behaviour of solids under constraint is an essential prerequisite to a more fundamental investigation of a particular material. All strains are considered recoverable, the vibrating stress levels being low and the behaviour of the material being described by its anelastic properties. The review takes no consideration of the high stress regime within which the logarithmic decrement has been found to increase strongly due usually to plastic losses.