Rotating concave eddy current probe
| DWPI Title: Rotating concave eddy current probe for detecting hidden fatigue crack, has electrical connection unit connecting magnetic test coil with current source, where central axis of coil is oriented relative to body`s central axis |
| Abstract: A rotating concave eddy current probe for detecting fatigue cracks hidden from view underneath the head of a raised head fastener, such as a buttonhead-type rivet, used to join together structural skins, such as aluminum aircraft skins. The probe has a recessed concave dimple in its bottom surface that closely conforms to the shape of the raised head. The concave dimple holds the probe in good alignment on top of the rivet while the probe is rotated around the rivet's centerline. One or more magnetic coils are rigidly embedded within the probe's cylindrical body, which is made of a non-conducting material. This design overcomes the inspection impediment associated with widely varying conductivity in fastened joints. |
| Use: Rotating concave eddy current probe for detecting the presence of a hidden fatigue crack located underneath a head of a raised head fastener i.e. raised head rivet, that is utilized for joining an aluminum skin of an aircraft fuselage or bridge assembly girder. |
| Advantage: The probe eliminates geometrical uncertainties associated with hand-held manual positioning, thus providing reliable, repeatable, accurate and consistent readings of the hidden fatigue crack. |
| Novelty: The probe (25) has a body (10) provided with a right circular cylinder made of a plastic/ceramic material, and a concave dimple recessed into the body. The dimple has an axisymmetric inner surface that closely conforms to the shape of a head (20) of a raised head fastener i.e. raised head rivet. A magnetic test coil (14) and a set of electrical leads are embedded inside the body for supplying current to the coil. An electrical connection unit connects the coil with a current source, where a central axis of the coil is oriented at an inclined angle relative to the body`s central axis. |
| Filed: 8/10/2006 |
| Application Number: US2006502085A |
| Tech ID: SD 7855.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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