Nondestructive Magnetic Measurement of Biaxial Stress Using Magnetic Fields Parallel and Perpendicular to the Stress Plane

Measuring the permeability of stressed steel by the magnetomotive-force-vane method with magnetization perpendicular to the surface

“…Test 7 ( , both positive) shows a monotonic decrease in with , which agrees with the predictions of [3]. Test 9 ( , both negative) shows an increase in with , which does not agree with [3]. Test 8 is particularly revealing.…”

“…The test specimen was the same as that used in [3], kindly loaned to us by Dr. M. Sablik. Refer to Appendix A for full details of the electrical and magnetic aspects.…”

“…Reference [3] contains a detailed discussion that includes the effect of possible undetected bending of the cruciform in Kwun and Burkhardt's test, that could have caused the discrepancies with Kashiwaya's results and with the authors' results.…”

“…Reference [3] predicts (a) that when the sum of the stresses in the -plane is positive, the permeability decreases monotonically as , and (b) when is negative, there may be no change of permeability with , or it may decrease. Which is correct in (b) must be decided by experiment.…”

“…However, it has the rather serious limitation that it cannot determine absolute stresses (unless there is only one stress). Theory described by Sablik et al [3] suggests that magnetic properties measured in the direction, with stresses in the and direction (as in Fig. 1) depend, with some limitations, on the sum of the principal stresses.…”