Applied and residual stress measurements using magnetic field sensors
First Claim
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1. A method for monitoring the stress on a structural article, said method comprising:
- affixing a stress-sensitive material layer to the structural article, the material having a stress sensitive electrical property that varies with stress;
simultaneously, using an electromagnetic sensor, measuring said stress sensitive electrical property and a second property that does not vary significantly with stress;
correcting for variations in the stress sensitive electrical property, that are not due to stress, with the second property to provide a corrected stress sensitive physical property; and
monitoring the stress on the structural article by relating said corrected stress sensitive electrical property to the stress on the article.
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Abstract
Methods are described for the use of conformable eddy-current sensors and sensor arrays for characterizing residual stresses and applied loads in materials. In addition, for magnetizable materials such as steels, these methods can be used to determine carbide content and to inspect for grinding burn damage. The sensor arrays can be mounted inside or scanned across the inner surface of test articles and hollow fasteners to monitor stress distributions. A technique for placing eddy-current coils around magnetizable fasteners for load distribution monitoring is also disclosed.
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Citations
23 Claims
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1. A method for monitoring the stress on a structural article, said method comprising:
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affixing a stress-sensitive material layer to the structural article, the material having a stress sensitive electrical property that varies with stress; simultaneously, using an electromagnetic sensor, measuring said stress sensitive electrical property and a second property that does not vary significantly with stress; correcting for variations in the stress sensitive electrical property, that are not due to stress, with the second property to provide a corrected stress sensitive physical property; and monitoring the stress on the structural article by relating said corrected stress sensitive electrical property to the stress on the article. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for monitoring the stress on a structural article, said method comprising:
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affixing a stress-sensitive material layer to the structural article, the material having a stress sensitive physical property that varies with stress; simultaneously, using an electromagnetic sensor, measuring said stress sensitive physical property and a second property that does not vary significantly with stress the sensor, the sensor being distinct from the stress-sensitive layer; correcting for variations in the stress sensitive property, that are not due to stress, with the second property to provide a corrected stress sensitive property; and monitoring the stress on the structural article by relating said corrected stress sensitive physical property to the stress on the article.
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Specification