An experimental study of the effects of superimposed
ultrasonic oscillation of the die in compression tests on aluminium
specimens is presented in this paper. In addition,
an implicit mechanical analysis using ABAQUS was developed
to provide some insight into the effects of stress superposition
and a change in the friction boundary condition
when ultrasonic excitation is applied to the lower platen.
The model predictions of the stress–strain relationship
compare favorably with experimental data. It provides an
explanation of the reduction in mean stress and its path
parallel to the static stress curve, so that some initial conclusions
can be drawn regarding dependency of stress
reduction on stress superposition and improvement of friction
during ultrasonic compression. However, the current
model cannot explain the variation of the stress amplitude
in the experimental data.