Patent ID: 8415947

Claim:
A method for stress assessment comprising: disposing a sensor proximate to a test material, the sensor having at least two drive windings and at least two sense elements, the drive windings connected in series for exciting a spatially periodic magnetic field of at least two periods when driven by an electric current, with the drive windings oriented in at least two different directions, positioned in at least two separate planes, and covering an overlapping area of the test material, the sense elements sensing a response to the test material, with each sense element positioned to measure a test material response primarily associated with one of the drive windings and not with the other drive windings; converting the response of each sense element into a property estimate for the test material in at least two directions, the property estimate exhibiting hysteresis as an applied load varies the stress of the test material; and correlating a property estimate to the stress of the test material in a first direction, with a property estimate in at least one second direction used to remove hysteresis effects on the property estimate in the first direction, the hysteresis effect determined by loading the test material to a known level and computing at least one correction factor that removes the hysteresis from the first direction.