NONLINEAR DAMPING AND HARMONIC-GENERATION IN IRON

The question of the phases of the third harmonic signals generated by dislocations is reconsidered. For an artificial model of breakaway, it is shown that the phase of the harmonic wave depends on the phase at which the breakaway takes place, and therefore on the amplitude of vib ration. Reversals of sign of the harmonic phase can occur at certain p hases of breakaway, leading to (partial) cancellation of waves from se gments of different breakaway stress. This effect seems likely to be t he major part of the phase cancellations previously reported and attri buted, in part, to screw-edge cancellation.