Materials problems in the construction of long-period pendulums

This paper reports the preliminary results of a study of the anelasticity of a Cu-1.8% Be alloy at strain frequencies between 10−2 and 10−3 Hz. The measurements were made using a vertical dumb-bell pendulum suspended near its centre of mass by a flexure pivot made from the Cu-Be alloy under test. Unexpectedly large anelastic effects were found at the lower frequencies. A mechanism explaining the observed behaviour is proposed based upon a hierarchical relaxation process having a continuum of relaxation times, such as might be expected from dislocations under stress making their way through an array of precipitates by fast diffusional processes.