Fig. 7.28 Effect of a crack on the pattern of eddy-current flow in a pipe More

Fig. 15.21 Principle of eddy current material testing. Source: Ref 15.2 , 15.26 More

Fig. 11.5 Cross-hole overheating: eddy-current distribution and heat nonuniformities due to presence of transverse holes. (a) Transverse hole, no plug. (b) Carbon steel part and carbon steel plug. (c) Carbon steel part and copper plug. (d) Multiholed part, no plugs. Source: Ref 5 More

Fig. 11.6 Longitudinal holes overheating: (a) eddy-current redistribution due to presence of longitudinal hole; (b) overheating areas due to presence of longitudinal holes. Source: Ref 5 More

Fig. 12.5 Inspection coil configurations for eddy-current testing, depending on the specimen shape. (a) A flat surface is normally examined by a flat, pancake-type coil. (b) A cylindrical specimen is examined using an encircling coil. (c) The interior of a tube can be examined by an inside More

Fig. 15 Two common types of inspection coils and the patterns of eddy current flow generated by the exciting current in the coils. (a) Solenoid type coil is applied to cylindrical or tubular parts. (b) Pancake type coil applied to a flat surface. Source: Ref 3 More

Fig. 16 Effect of a crack on the pattern of eddy current flow in a pipe. Source: Ref 3 More

Fig. 17 Principal elements of a typical system for eddy current inspection of bar or tubing. See description in text. Source: Ref 3 More

Fig. 21 Variation in density of eddy current as a function of depth below the surface of a conductor, known as skin effect. Source: Ref 3 More

Fig. 23 Types and applications of coils used in eddy current inspection. (a) Probe type coil applied to a flat plate for crack detection. (b) Horseshoe shape, or U-shape, coil applied to a flat plate for laminar flaw detection. (c) Encircling coil applied to a tube. (d) Internal, or bobbin More

Fig. 24 Multiple coils used in eddy current inspection. (a) Absolute coil arrangement. (b) Differential coil arrangement. Source: Ref 3 More

Fig. 25 Four types of eddy current instruments. (a) A simple arrangement, in which voltage across the coil is monitored. (b) Typical impedance bridge. (c) Impedance bridge with dual coils. (d) Impedance bridge with dual coils and a reference sample in the second coil. Source: Ref 3 More

Fig. 8 Coil assembly for the inspection of steel bars by the eddy current system. Dimensions in inches. Source: Ref 1 More

Fig. 9 Schematic of a rotating probe type eddy current flaw detector. Source: Ref 2 More

Fig. 10 Plot of eddy current signal output versus flaw depth to gage detectability of flaws in cold drawn bars. Source: Ref 2 More

Fig. 11 Eddy current flaw detection method for cold-drawn hexagonal bars. (a) Location of artificial flaws ranging from 0.5 to 19 mm (0.020 to ¾ in.) below probe position. (b) Schematic of setup for standard voltage comparison (encircling coil) method (left) and plot of signals obtained More

Fig. 12 Plot of eddy current signal output versus flaw depth to measure detectability of flaw, specifically material flaws (open circles) and process induced cracks (closed circles), in cold drawn hexagonal bars. Source: Ref 2 More

Fig. 13 Plot of eddy current signal output versus flaw depth to measure detectability of flaws, specifically cracks (open circles) and scabs (closed circles), in cold drawn wires. Source: Ref 2 More

Fig. 15 Schematic of eddy current flaw detection system used to inspect sheared bolt illustrated in Fig. 14 . Source: Ref 2 More