Format:
15
ISSN:
0018-9464
Content:
We propose a procedure to determine optimal magnet systems in the framework of the nondestructive evaluation technique Lorentz force eddy-current testing (LET). The underlying optimization problem is clearly defined considering the problem specificity of nondestructive testing scenarios. The quantities involved are classified as design variables, and system and scaling parameters to provide a high level of generality. The objective function is defined as the absolute defect response signal (ADS) of the Lorentz force resulting from an inclusion inside the object under test. Associated constraints are defined according to the applied force sensor technology. A numerical procedure based on the finite-element method is proposed to evaluate the nonlinear objective and constraint functions, and the method of sequential quadratic programming is applied to determine unconstrained and constrained optimal magnet designs. Consequently, we propose a new magnet design based on the Halbach principle in combination with high saturation magnetization iron-cobalt alloys. The proposed magnet system outperforms currently available cylindrical magnets in terms of weight and performance. The corresponding defect response signal is increased up to 180% in the case of small defects located close to the surface of the specimen. The combination of active and passive magnetic materials provides an increase of the ADS by 15% compared with the magnet designs that are built solely from permanent magnet material. The proposed procedure provides a highly adaptive optimization strategy in the framework of LET and proposes new magnet systems with inherently improved characteristics.
In:
Institute of Electrical and Electronics Engineers, IEEE transactions on magnetics, New York, NY : IEEE, 1965, 51(2015), 9, Seite 6201415, 0018-9464
In:
volume:51
In:
year:2015
In:
number:9
In:
pages:6201415
In:
extent:15
Language:
English
Author information:
Weise, Konstantin 1986-
Author information:
Ziolkowski, Marek
Author information:
Brauer, Hartmut 1953-
Author information:
Töpfer, Hannes 1962-
