Method of detecting widespread fatigue and cracks in a metal structure
First Claim
1. A method of detecting widespread fatigue in a metal structure comprising the following steps:
- providing an inductive sensor array;
imposing through the sensor array an electromagnetic field in the metal structure;
sensing a resulting electromagnetic response of the structure to the imposed magnetic field;
transforming the electromagnetic response to an absolute conductivity of the metal structure; and
analyzing the conductivity pattern for reduction in conductivity indicative of widespread fatigue associated with microcrack formation.
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Accused Products
Abstract
An apparatus and a method of detecting wide spread fatigue damage (WFD) on aircraft using the absolute conductivity of the metal. A meandering winding magnetometer (MWM) having a plurality of parallel spaced linear conductor elements are placed in proximity to the aircraft. An electromagnetic field is imposed on the aircraft and the resulting response is sensed. The response is transformed to determine the conductivity of the aircraft structure. The mapping of the conductivity of the aircraft structure produces an indication where microcracks are located in the structure. These early indications of the density, spatial distribution and spatial orientation, as well as the size, of the microcracks give the user an indication of WFD.
75 Citations
23 Claims
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1. A method of detecting widespread fatigue in a metal structure comprising the following steps:
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providing an inductive sensor array;
imposing through the sensor array an electromagnetic field in the metal structure;
sensing a resulting electromagnetic response of the structure to the imposed magnetic field;
transforming the electromagnetic response to an absolute conductivity of the metal structure; and
analyzing the conductivity pattern for reduction in conductivity indicative of widespread fatigue associated with microcrack formation. - View Dependent Claims (2, 3, 4)
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5. A method of detecting widespread fatigue in a metal structure comprising the following steps:
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disposing a plurality of parallel spaced linear conductor elements in proximity to the metal structure;
imposing through the conductor elements an electromagnetic field in the metal structure with a dominant spatial wavelength;
sensing a resulting electromagnetic response of the structure to the imposed magnetic field;
transforming the electromagnetic response to conductivity of the metal structure; and
analyzing the conductivity pattern for reduction in conductivity indicative of widespread fatigue. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of detecting cracks in an aircraft structure comprising the following steps:
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disposing a plurality of parallel, spaced linear conductor elements in proximity to the aircraft structure;
through the conductor elements imposing an electromagnetic field in the aircraft structure with a dominant spatial wavelength;
sensing a resulting electromagnetic response of the structure to the imposed magnetic field;
transforming the electromagnetic response to absolute conductivity of the structure; and
analyzing the conductivity pattern for reduction in conductivity indicative of cracks. - View Dependent Claims (20, 21, 22, 23)
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Specification