The application of ultrasonic vibration to the plastic
deformation of metals has been widely investigated. Many
early investigations reported that by superimposing an
ultrasonic excitation on the static load during plastic deformation,
the flow stress was reduced. This reduction in flow
stress in ultrasonic metal working was attributed to several
phenomena including dynamic effects of high frequency
vibrated tools, alterations in material properties, local
increases in temperature and changes to the interface friction
condition [1–3].
Eaves et al. [4], in their review of ultrasonic vibration in
uniaxial tests of metal, attempted to clarify many of the
seemingly conflicting reports in the literature, to identify
if the reduction in flow stress was due to oscillatory stress
superposition or real changes in the interface friction or
metallurgical properties of the metals. One explanation of