Stress-pulse propagation in solids: a closer look at dispersion

It is found that when a short-duration plane-compressive stress pulse is propagated in various solid metals, the initially compressive pulse develops a tensile tail indicative of dispersion. This dispersion occurs without the stress pulse impinging upon external boundaries or upon any classically recognized internal boundaries. This phenomenon also occurs in water in which it is demonstrated experimentally that the dispersion mechanism is the scattering of the wave by the small amount of air normally present in water. It is believed that the pulse dispersion in the metals is likewise caused by scattering of the wave by the very small but extremely numerous defect-related voids that exist in all metals, even if they are carefully prepared metallic single crystals.