Structural health monitoring
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Abstract
The present invention relates to testing structures or bodies to determine if they contain defects. The defects may be, for example, cracks, delamination etc. Conventional non-destructive testing exploits the non-linearities of such defects. The non-linearities produce intermodulation products in the form of side-bands of an excitation signal. The amplitudes of the side-bands are used to provide an indication of the structural health of the body. However, it has been found that such methods of testing bodies suffer from the vagaries of the environment, temperature and transducer manufacturing tolerances etc. This can lead to inaccurate test results. Suitably, embodiments of the present invention provide a method of determining the structural health of a body; the method comprising the steps of identifying at least one phase characteristic of a signal represented by first data, the first data being, or having been, derived from the body while bearing at least a guided wave, produced in response to application of a first excitation signal to the body, and a second excitation signal; and providing a measure of the structural health of the body using the at least one phase characteristic. More accurate testing can be performed that is independent of at least some of the above-mentioned vagaries by basing the assessment of the structural body on defect induced phase modulation.
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Citations
159 Claims
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1-84. -84. (canceled)
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85. A method of determining the structural health of a body;
- the method comprising the steps of identifying at least one phase characteristic of a signal represented by first data, the first data being derived from the body while bearing
(a) at least a guided wave, produced in response to application of at least a first excitation signal to the body, and (b) a second excitation signal, and providing a measure of the structural health of the body using the at least one phase characteristic. - View Dependent Claims (86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 159)
- the method comprising the steps of identifying at least one phase characteristic of a signal represented by first data, the first data being derived from the body while bearing
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112. An apparatus for of determining the structural health of a body;
- the apparatus comprising means for identifying at least one phase characteristic of a signal represented by first data, the first data being derived from the body while bearing
(c) at least a guided wave, produced in response to application of at least a first excitation signal to the body, and (d) a second excitation signal, and means for providing a measure of the structural health of the body using the at least one phase characteristic. - View Dependent Claims (113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136)
- the apparatus comprising means for identifying at least one phase characteristic of a signal represented by first data, the first data being derived from the body while bearing
- 137. An apparatus as claimed in 133, further comprising means for determining a crack length, L, from the damage index, D.
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139. A method of analysing a body;
- the method comprising the steps of;
applying a first excitation signal, via a first transducer, to the body to produce a guided wave within the body;
applying a second excitation signal, via a second transducer, to the body;
the second excitation signal being arranged to influence a phase characteristic of the guided wave in the presence of a defect within the body;
recording, via a transducer, data associated with the guided wave. - View Dependent Claims (140, 141, 142, 143, 144, 145, 146, 147, 148)
- the method comprising the steps of;
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149. An apparatus for analysing a body;
- the apparatus comprising;
means for applying a first excitation signal, via a first transducer, to the body to produce a guided wave within the body;
means for applying a second excitation signal, via a second transducer, to the body;
the second excitation signal being arranged to influence a phase characteristic of the guided wave in the presence of a defect within the body;
means for recording, via a transducer, data associated with the guided wave. - View Dependent Claims (150, 151, 152, 153, 154, 155, 156, 157, 158)
- the apparatus comprising;
Specification