StressProbe - a new non-contacting stress measurement technique

A new non-contacting stress measurement technique, the StressProbe, based on the piezomagnetic effect has recently come into service. It utilises inducing and sensing coils that are arranged so that an almost linear response to stress is possible. Theoretical work already reported has shown that it can be used for measurement of residual stress, dead loads and cyclic stress. In general, a calibration is needed for the interpretation of StressProbe measurements and this may be obtained from a simple three-point bend or axial load tests. For some metals, the StressProbe response shows hysteresis during a static load-unload test. For these metals, it has been found that using a demagnetisation cycle between each measurement eliminates most of the hysteresis loop. For continuous cyclic loading, this behaviour does not occur.