Instrumentation and method for monitoring change in electric potential to detect crack growth
First Claim
1. Instrumentation for monitoring crack growth comprising:
- a specimen of a conductive material to be analyzed for crack growth propagation, the specimen having a first specimen surface with a preformed starter crack of a predetermined size therein;
a plurality of current leads attached to the specimen, the current leads configured to pass electric current through the specimen;
a layer of insulating material disposed on each of opposite sides of the starter crack on a portion of the first specimen surface;
a layer of conductive material disposed on each layer of insulating material, wherein a portion of each layer of conductive material is in electrical contact with the first specimen surface; and
a pair of sensing leads, one sensing lead attached to each layer of conductive material.
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Abstract
Instrumentation for monitoring crack growth using a change in electric potential across a starter crack as the crack propagates is disclosed. The instrumentation includes a specimen of a material to be analyzed for crack growth propagation having a surface with a starter crack formed therein, a plurality of current leads to pass electric current through the specimen, a layer of insulating material disposed on each of opposite sides of the crack, a layer of conductive material disposed on each layer of insulating material, where a portion of each layer of conductive material is in electrical contact with the first specimen surface, and a pair of sensing leads, one sensing lead attached to each layer of conductive material. A method for using the instrumentation to monitor crack growth by measuring is also disclosed.
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Citations
22 Claims
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1. Instrumentation for monitoring crack growth comprising:
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a specimen of a conductive material to be analyzed for crack growth propagation, the specimen having a first specimen surface with a preformed starter crack of a predetermined size therein;
a plurality of current leads attached to the specimen, the current leads configured to pass electric current through the specimen;
a layer of insulating material disposed on each of opposite sides of the starter crack on a portion of the first specimen surface;
a layer of conductive material disposed on each layer of insulating material, wherein a portion of each layer of conductive material is in electrical contact with the first specimen surface; and
a pair of sensing leads, one sensing lead attached to each layer of conductive material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for monitoring crack growth in a specimen having a first specimen surface, the first specimen surface including a starter crack of predetermined size formed therein, the starter crack having opposite sides, the method comprising the steps of:
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applying a layer of insulating material on a portion of the first specimen surface on each of opposite sides of the starter crack;
applying a layer of conductive material over each layer of insulating material, a portion of each layer of conductive material in electrical contact with the first specimen surface in at least one location;
providing a pair of sensing leads, each sensing lead having opposed ends;
attaching an end of each sensing lead to each layer of conductive material and attaching an opposed end of each sensing lead to a means for measuring electric potential, the sensing leads configured to measure a change in electric potential across the starter crack;
providing at least two current leads, each current lead having opposed ends;
attaching an end of the least two current leads to the specimen, the opposed end of each lead connected to a current source;
passing an electric current through the current leads; and
measuring a change in electric potential across the starter crack to monitor changes in the electric potential indicative of growth in the starter crack. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. Instrumentation for monitoring crack growth comprising:
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a specimen of a material to be analyzed for crack growth propagation, the specimen having a first specimen surface with a starter crack formed therein, the starter crack having a width of less than or equal to 8 mils and a depth of less than or equal to 4 mils;
a plurality of current leads attached to the specimen, the current leads configured to pass electric current through the specimen;
a layer of insulating material disposed on each of opposite sides of the starter crack on the first specimen surface;
a layer of conductive material disposed on each layer of insulating material, wherein a portion of each layer of conductive material is in electrical contact with the first specimen surface at a distance of less than or equal to 17 mils from the starter crack; and
a pair of sensing leads, one sensing lead attached to each layer of conductive material at a location that overlies the layer of insulating material.
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Specification