CST – Computer Simulation Technology

TEAM Benchmark 8 Coil above a crack

The structure consists of a block of austenitic stainless steel which contains a rectangular slot, representing a flaw (see Fig. 1). A differential probe moves across the surface of the block. The probe is a cylinder with an inducing solenoid 44 mm in diameter and two smaller receptive solenoids 10 mm in diameter. Each of these two solenoids is placed in a branch of a Wheatstone's bridge. Therefore, the measured voltage signal is proportional to the difference of the magnetic fluxes in the two receiver solenoids.



Figure 1: Structure geometry

Since the benchmark requires results for various relative positions of the coil and crack, the x and y coordinates of the crack were parameterized.

The excitation coil was defined by using the "coil" feature of CST EM STUDIO® (CST EMS). The receiving coils do not need to be modeled as 3D objects. Instead, the magnetic fluxes at the locations of the receiving coils are calculated in the postprocessing phase....

Since the signal which needs to be detected is very small, it can be affected by large numerical errors. In order to avoid this, the "perturbation" flux in each receiving coil was calculated, by computing the difference between the the magnetic fluxes with and without a crack. The corresponding magnetic flux densities are shown in Figures 2-4.



Figure 2: Magnetic flux without crack


Figure 3: Magnetic field in the presence of the crack


Figure 4: "Perturbation" magnetic field

The difference of the perturbation magnetic fluxes in the two receiving coils, for different positions of the crack, was computed.

The signal trajectory in the Real-Imaginary plane, for a coil placed 28 mm above the plate and moved parallel to the crack is plotted in Figure 5, showing a good agreement with the measured results (Figure 6).



Figure 5: Simulated signal trajectory, motion parallel to the flow (coil position 28 mm above the plate)


Figure 6: Measured trajectory, motion parallel to the flow

Rate this Article

0 of 5 Stars
5 Stars
0%
4 Stars
0%
3 Stars
0%
2 Stars
0%
1 Stars
0%
contact support

Your session has expired. Redirecting you to the login page...

We use cookie to operate this website, improve its usability, personalize your experience, and track visits. By continuing to use this site, you are consenting to use of cookies. You have the possibility to manage the parameters and choose whether to accept certain cookies while on the site. For more information, please read our updated privacy policy


Cookie Management

When you browse our website, cookies are enabled by default and data may be read or stored locally on your device. You can set your preferences below:


Functional cookies

These cookies enable additional functionality like saving preferences, allowing social interactions and analyzing usage for site optimization.


Advertising cookies

These cookies enable us and third parties to serve ads that are relevant to your interests.