Experiment and theory in anelasticity

We briefly review the results of experimental and theoretical studies of anelasticity at low frequencies and we discuss the essential features of models that explain consistently the key aspects of this behaviour. In our original paper on this topic we reported that damping in a compound pendulum at frequencies in the range 10 -3 -10 -2 Hz was consistent with an imaginary component of Young's modulus for the Cu-Be suspension that was independent of frequency. Damping with this characteristic frequency dependence can also be described in terms of viscous damping whose magnitude varies as the inverse of frequency. With the hindsight provided by our further work we now realize that stick-slip processes can give rise to such losses, not only in the suspensions but also in the structures and clamping mechanism of the suspensions of long-period pendulums.