Showing papers on "Eddy-current testing published in 1975"

Method and apparatus for testing conductivity using eddy currents

Abstract: A method and apparatus for measuring conductivity of nonferrous metals using eddy current test principles in which conductivity is measured as a direct linear function of the period of the inducing signal at a preselected phase angle between the inducing and induced signals and is displayed directly in percentage of the International Annealed Copper Standard.

Eddy current defect simulator and method

Abstract: A method and apparatus for calibrating an eddy current inspection system is disclosed which utilizes electronic workpiece flaw simulator circuitry for simulating a response produced by a flaw in a ferromagnetic calibration workpiece. The inspection system includes a detector probe which generates an electromagnetic field and is responsive to changes in the electromagnetic field. The workpiece flaw simulator circuitry is positioned in the electromagnetic field adjacent the detector probe. The workpiece flaw simulator circuitry controllably alters the electromagnetic field near the detector probe in a manner similar to a change in the field which would result from a workpiece having a defect of known severity passing through the field. In a preferred embodiment, the workpiece flaw simulator circuitry includes a reaction coil and a resistive loading network which are coupled together to produce inductive and resistive components of impedance in the simulator circuitry. The loading network is adjustable to provide differing predetermined loadings on the reaction coil to the electromagnetic field sensed by the detector probe and thus simulate defects of known severity in the type of workpiece under test.

Inductive detection of underground metallic pipes

Abstract: A widely used instrument for locating underground metallic pipes consists of two coils: one of which (the transmitting coil) excites eddy currents in the pipe, and the other (the receiving coil) detects the magnetic field of. these eddy currents. Irregularities in the response of this type of instrument appear during certain search operations. These irregularities cause uncertainty about the position of the line of the pipe. They are explained quantitatively in this paper. The analysis shows how the reaction field of the pipe varies with the depth and diameter of the pipe, and with its electrical and magnetic properties. A theoretical estimate of the diameter of the smallest pipe that can be detected is given.

Characterization of irradiated fuel rods using pulsed eddy current techniques

Abstract: A number of irradiated fuel rods and unfueled zircaloy cladding tubes (''water tubes'') were obtained from the Saxton reactor through arrangements with the Westinghouse Electric Corporation for use in subsequent irradiation effects and fuel behavior programs. A comprehensive nondestructive and corroborative destructive characterization program was undertaken on these fuel rods and tubes by ANC to provide baseline data on their characteristics prior to further testing and for comparison against post-post data. This report deals primarily with one portion of the NDT program performed remotely in the hot cells. The portion of interest in this paper is the pulsed eddy current inspection used in the nondestructive phase of the work. 6 references. (auth)