Accession Number : ADD011554

Title :   Eddy Current Test Probe with Circumferential Segments and Method of Testing Material Surrounding Fastener Holes.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Lakin,K M

Report Date : 22 Jan 1985

Pagination or Media Count : 8

Abstract : This patent discloses an instrument having a multi-segmented cup core of a high permeability material with a center post. The outer wall of the cup contains equidistant holes and slots through which a plurality of individual windings are constructed to form a circulary array of pick-up coils. A primary winding or search coil is constructed around the center post. Excitation of the search coil induces eddy currents in adjacent multi-layered bolt hole regions which in turn produce a voltage in each of the pick-up coils. As a crack in the material under test will cause an abnormal distribution of eddy currents, a comparison of the voltage measurements of the specimen under test with those of a reference sample will detect the presence of a crack and its corresponding orientation.

Descriptors :   *Patents, *Test equipment, *Eddy currents, Nondestructive testing, Defects(Materials), Cracks, Electric coils, Probes, Fastenings, Holes(Openings)

Subject Categories : Metallurgy and Metallography
      Couplers, Fasteners, and Joints

Distribution Statement : APPROVED FOR PUBLIC RELEASE