ELECTROMAGNETIC METHODS FOR NDE OF METAL FATIGUE CRACKS: PRACTICAL TECHNIQUES AND THEORETICAL MODELS

The available electromagnetic methods used for the detection and measurement of metal fatigue cracks are first described. A distinction is drawn between the eddy-current and potential drop methods, which detect the crack primarily because of the break in electric conductivity, and the magnetic particle and flux leakage methods which detect the break in magnetic permeability. The importance of the skin-effect is stressed and the various frequency regimes distinguished. Theoretical models of each method are described and compared and their strengths and weaknesses discussed.

[1]  R. E. Beissner,et al.  Theory of eddy currents induced by a nonsymmetric coil above a conducting half‐space , 1984 .

[2]  S B Palmer,et al.  The magnetic leakage field of surface-breaking cracks , 1986 .

[3]  C. M. Fortunko,et al.  Inversion of Eddy Current Signals in a Nonuniform Probe Field , 1983 .

[4]  Eddy currents in a conducting cylinder with a crack , 1979 .

[5]  David L. Atherton,et al.  Finite element calculation of magnetic flux leakage detector signals , 1987 .

[6]  W. D. Dover,et al.  Detection and measurement of cracks in threaded bolts with an a. c. potential difference method , 1983, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[7]  Ka Peters,et al.  Application of the Electrical Potential Method to Crack Length Measurements Using Johnson's Formula , 1981 .

[8]  S. K. Burke,et al.  Interaction of induced currents with cracks in thin plates , 1988, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[9]  R. Beissner.  Boundary element model of eddy current flaw detection in three dimensions , 1986 .

[10]  J. C. Verite.  A COIL OVER A CRACK. (RESULTS FOR BENCHMARK PROBLEM 8 OF TEAM WORKSHOP) , 1990 .

[11]  David L. Atherton,et al.  Finite element calculations on the effects of permeability variation on magnetic flux leakage signals , 1987 .

[12]  F. Förster.  New findings in the field of non-destructive magnetic leakage field inspection , 1986 .

[13]  Harold A. Sabbagh,et al.  A MODEL OF EDDY-CURRENT PROBES WITH FERRITE CORES , 1989 .

[14]  T. Senior.  Impedance boundary conditions for imperfectly conducting surfaces , 1960 .

[15]  Klaus-Jürgen Bathe,et al.  On the calibration of the electrical potential technique for monitoring crack growth using finite element methods , 1979 .

[16]  Yr Fiorini,et al.  Finite Element Modeling of Magnetic Field/Defect Interactions , 1975 .

[17]  C. Dodd,et al.  ANALYTICAL SOLUTIONS TO EDDY--CURRENT PROBE COIL PROBLEMS. , 1968 .

[18]  B. A. Auld,et al.  Eddy-Current Reflection Probes: Theory and Experiment , 1989 .

[19]  H. Libby.  Introduction to Electromagnetic Nondestructive Test Methods , 1971 .

[20]  W. M. Thornton,et al.  The Measurement of the Thickness of Metal Walls from One Surface Only, by an Electrical Method* , 1938 .

[21]  D. H. Michael,et al.  The measurement of surface cracks in metals by using a. c. electric fields , 1982, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[22]  Efficient calculation of eddy current responses due to defects , 1990 .

[23]  Adam Miles Lewis,et al.  The modelling of electromagnetic methods for the nondestructive testing of fatigue cracks , 1991 .

[24]  D. Thompson,et al.  Review of Progress in Quantitative Nondestructive Evaluation , 1982 .

[25]  G. G. Garrett,et al.  Crack-growth monitoring: Optimisation of the electrical potential technique using an analogue method , 1971 .

[26]  C. J. Beevers,et al.  The Measurement of crack length and shape during fracture and fatigue , 1980 .

[27]  A. M. Lewis,et al.  A theoretical model of the response of an eddy-current probe to a surface-breaking metal fatigue crack in a flat test-piece , 1992 .

[28]  D. H. Michael,et al.  Thin-skin electromagnetic fields in the neighbourhood of surface-breaking cracks in metals , 1991, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[29]  S. K. Burke,et al.  Eddy‐current inspection of cracks in a multilayer conductor , 1990 .

[30]  D. Hughes.  V. Induction-balance and experimental researches therewith , 1879 .

[31]  G. Gille.  The electrical potential method and its application to non-destructive testing , 1971 .

[32]  David Jiles,et al.  Review of magnetic methods for nondestructive evaluation (Part 2) , 1990 .

[33]  S. K. Burke,et al.  Eddy-current NDI of cracks in thin plates , 1987 .

[34]  The detection and measurement of overlapping fatigue cracks at welded joints by thin-skin electromagnetic fields , 1988, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[35]  R. Collins,et al.  A study of the leakage of surface electromagnetic fields through holes and cracks in metal plates , 1989, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[36]  D. H. Michael,et al.  The measurement of surface crack inclination in metals using AC electric fields , 1988 .

[37]  Albert Feldman,et al.  Eddy‐current losses due to a surface crack in conducting material , 1977 .

[38]  Frank Thomas Smith,et al.  Characterization of surface-breaking cracks in metal sheets by using AC electric fields , 1989, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[39]  T. R. Schmidt.  The Casing Inspection Tool — An Instrument for the In-Situ Detection Of External Casing Corrosion in Oil Wells , 1961 .

[40]  R. Ritchie,et al.  Optimization of the Electrical Potential Technique for Crack Growth Monitoring in Compact Test Pieces Using Finite Element Analysis , 1979 .

[41]  J. H. Rose,et al.  Electromagnetic induction (eddy currents) in a conducting half‐space in the absence and presence of inhomogeneities: A new formalism , 1990 .

[42]  J. Bowler.  Eddy current calculations using half‐space Green’s functions , 1987 .

[43]  D. H. Michael,et al.  The inversion of surface potential measurements to determine crack size and shape , 1988 .