| Summary: | This paper investigates the potential of a non-destructive magnetic technique based on Barkhausen noise emission for the monitoring of prestressing bars with respect to their undesired over-stressing. Barkhausen noise signals are correlated with tensile stress, residual stresses, and microhardness measurements. It was found that prestressing bars exhibit strong magnetic anisotropy which becomes more pronounced along with the increasing degree of the bar’s over-stressing. Barkhausen noise emission becomes strongly attenuated in the direction of the tensile stress at the expense of the perpendicular direction. However, the Barkhausen noise emission in the direction of the tensile stress exhibits a continuous and remarkable decrease, whereas the Barkhausen noise steep increase for lower degrees of over-stressing is followed by early saturation for higher over-stressing. This study demonstrates that the Barkhausen noise technique is capable of distinguishing between the prestressing bars loaded below yielding, and those which are over-stressed.
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