Die Theorie der inneren Dämpfung schwingender fester Körper

This paper gives a surview on the theories existing today for damping of oscillating solids. The oldest are the purely formal representations of solids by Maxwell or Kelvin elements, today extended to a point where the solid is considered as a parallel wiring of such elements with a finite or infinite number of different relaxation times. From a physical point of view it must be distinguished between damping effects depending on the shape of the oscillating solids like damping by macroscopic heat currents and such effects due to the oscillating matter alone. For these latter Prandtl has elaborated a theory starting from the fact that matter consists of molecules; this theory has been extended and brought into a shape clearer from a mathematical point of view by Eyring. It includes as special cases damping independent of frequency and the true relaxation phenomena of which the most important are discussed.