11. Surf Coils - Cracks with Low Skin Depths (SF-HFCRK.EXE)

Note (2012-09-03): A bug was noticed in the program SF-HFCRK.EXE. A fixed version is now uploaded on this page. If you previously downloaded the program, it is advisable to discard that one and use the one currently available at this site instead.

A download for SF-HFCRK.EXE is available. To use it, download the SF-HFCRK.EX_ file and rename it to SF-HFCRK.EXE. This program will only run on PC computers with operating systems from MS-DOS to Windows XP. It does not run on PCs with Windows 7 operating system unless an MS-DOS emulator program like "DOS-Box" is installed.

This program was developed to model eddy current inspections detecting and sizing surface cracks in steel at frequencies of 100 kHz or greater.

All units are MKS.

SF-Y-CRK.EXE calculates the CHANGE in induced voltage in a surface transmit-receive coil configuration due to an infinitesimally thin partial through-wall planar flaw in a nearby plate.

This program calculates crack signals based on an approximation assuming the crack behaves like a thin wave-guide to the electromagnetic energy from the test coil. [Auld B.A., Moulder J.C., Jefferies S., Shull P.J., Ayter S. and Kenney J., “Eddy-Current Reflection Probes: Theory and Experiment”, Research in Nondestructive Evaluation, 1989.] The orientation of this flaw is user defined. Results from this program will not be valid for a 100% through-wall crack. In addition, this program only generates valid results when with relatively high test frequencies or very small skin depths. The crack depth should be much larger than the electromagnetic skin depth of penetration.

Crack Depth >> Electromagnetic Skin Depth.

This program can account for the influence of eddy current and magnetic field in two lower plates and one upper plate as well as calculate a flaw signal in any of these plates as well. The plates have finite thickness, but they are assumed to have infinite radial extent. The plate materials are assumed to be linear, homogeneous and isotropic with user defined electrical conductivity and relative magnetic permeability.

An impedance coil signal can be simulated by giving the receive coil the same physical dimensions of the transmit coil, and by making the centre-to-centre separation between the coils near zero (say ~ 1E-10 m or 1 Angstrom).

SF-HFCRK.EXE generates a ".dat" file with real and imaginary voltage components. The program also generates a ".val" file with text information on the user input parameters defining the configurations that were solved.