Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Patent
1998-01-05
2000-06-13
Noori, Max
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
324209, 73779, G01N 2904
Patent
active
060734930
ABSTRACT:
In a method of diagnosing the fatigue life of structural steelwork according to the present invention, a Barkhausen noise measurement is performed under the condition of 5 .mu.m.ltoreq.d.ltoreq.1 mm where d is the detection depth of Barkhausen noise, by using a magnetic head constituted by an air-core coil detection head and a magnetic excitation head obtained by winding a copper wire such as an enameled wire on a U-shaped core made of a soft magnetic material such as a silicon steel sheet or an amorphous magnetic material. The degree of fatigue damage of a target measurement portion is diagnosed using the root-mean-square (RMS) voltage or voltage amplitude value of the Barkhausen noise. According to this method, the degree of fatigue and degradation by stress and strain in the structural steelwork can be accurately diagnosed prior to development of cracking without any limitation on diagnostic locations. A member of steelwork having a life diagnostic function is obtained by mounting the above magnetic head on a brace- or wall-like vibration-damping device made of very low-yield steel. According to this member of steelwork, the wall or covering material of a bridge or the like need not be removed even in practicing a fatigue life diagnosis. The degree of fatigue degradation in structural steelwork can be easily and accurately diagnosed prior to development of cracking even in a location where an operator cannot access due to the structural limitation.
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Inaguma Toru
Nakata Yasuhiro
Sakamoto Hiroaki
Yazaki Mitsuhiko
Nippon Steel Corporation
Noori Max
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