10. Surface Coils - Partial Through-wall Crack (SF-X-CRK.EXE)

A download for SF-X-CRK.EXE is available. To use it, download the SF-X-CRK.EX_ file and rename it to SF-X-CRK.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.

All units are MKS.

SF-X-CRK.EXE calculates the CHANGE in induced voltage in a surface transmit-receive coil configuration due to a long infinitesimally thin partial through-wall planar flaw in a nearby plate. This program calculates crack signals based on an approximation using the sum of signals from a sum of slightly overlapping surface semi-circular cracks. Radius of the semi-circles in the approximation is equal to the depth of the rectangular crack under consideration. The number of semi-circles is approximately equal to the entire length of the crack under consideration divided by twice the radius of the semi-circles.

The length of the crack should be at least 4 times as much as the depth. The orientation of this flaw is in the "x" direction with respect to the diagram above. Results from this program will not be valid for a 100% through-wall crack. In addition, this program only generates valid results when with low test frequencies or skin depths. The crack depth should be no larger than the electromagnetic skin depth of penetration.

This program only accounts for the interaction of the eddy current with the flaw, not a magnetic field interaction like in ferromagnetic materials. Therefore, the flaw signal calculation should only be considered valid if the flaw is in a NONMAGNETIC plate.

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-X-CRK.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.