Pulsed magneto-acoustic emission sensor array for stress measurement and material.’characterisation

This paper introduces a new method of pulsed magnetic acoustic emission (MAE) for stress detection
and material characterisation and investigates the viability of implementing an acoustic emission
sensor array for enhanced location information and noise suppression. Pulsed excitation can provide
wide spectral components for non-destructive evaluation and material characterisation and lead to
greater sensitivity over a range of depths and the extraction of depth information through
time/frequency analysis. After introducing the system set-up, several experiments including stress
variation and residual stress orientation are outlined, in comparison with magnetic Barkhausen noise
(MBN) and magnetic field intensity measurement. Due to differences in the generation of MAE and
MBN the techniques are sensitive to different properties at different depths, so fusion of data from the
two techniques is investigated. The work concludes with an investigation into the implementation of an
acoustic emission sensor for MAE measurements. Possible signal processing techniques are
investigated, including time delay calculations for location information and addition of sensor signals
for noise suppression.