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Advanced modeling in Lorentz force eddy current testing
Nowadays, there is an increasing demand on reliable and efficient methods to evaluate materials and components in a nondestructive way. Particularly in the field of aerospace engineering, the components are subject to fulfill high quality and safety standards, which necessitate methods with a high accuracy, repeatability and inspection speed. This work deals with the nondestructive testing method Lorentz force eddy current testing. Unlike traditional eddy current methods, the induction process is based on relative motion between a permanent magnet and the object under test. An integral part of this thesis is the development of a new magnet system with improved characteristics. The proposed design is based on the Halbach principle and is made of Neodymium-Iron-Boron alloys. Besides that, it contains a piece made of highly saturating iron-cobalt. In this sense, it was possible to increase and focus the magnetic flux density in the vicinity of the specimen. The development of a decent optimization strategy allows to determine problem specific magnet designs in dependence on the measurement requirements. In the further course of this thesis, numerical simulations are performed addressing the uncertainty and sensitivity analysis of the system. Therefore, the model parameters are investigated in terms of their statistical properties. The resulting stochastic electromagnetic field problem is solved by means of the generalized polynomial chaos technique in combination with the finite element method. This enabled the identification of most influencing parameters in the system. In the context of the uncertainty analysis, it is observed that the velocity obeys characteristic oscillations. In order to deepen the understanding of this phenomenon, an analytical approach is presented to evaluate the electromagnetic fields and forces while taking into account the resistive and inductive character of the moving conductor. Finally, an alternative Lorentz force eddy current testing system is proposed where the object under test is ...
Advanced modeling in Lorentz force eddy current testing
Nowadays, there is an increasing demand on reliable and efficient methods to evaluate materials and components in a nondestructive way. Particularly in the field of aerospace engineering, the components are subject to fulfill high quality and safety standards, which necessitate methods with a high accuracy, repeatability and inspection speed. This work deals with the nondestructive testing method Lorentz force eddy current testing. Unlike traditional eddy current methods, the induction process is based on relative motion between a permanent magnet and the object under test. An integral part of this thesis is the development of a new magnet system with improved characteristics. The proposed design is based on the Halbach principle and is made of Neodymium-Iron-Boron alloys. Besides that, it contains a piece made of highly saturating iron-cobalt. In this sense, it was possible to increase and focus the magnetic flux density in the vicinity of the specimen. The development of a decent optimization strategy allows to determine problem specific magnet designs in dependence on the measurement requirements. In the further course of this thesis, numerical simulations are performed addressing the uncertainty and sensitivity analysis of the system. Therefore, the model parameters are investigated in terms of their statistical properties. The resulting stochastic electromagnetic field problem is solved by means of the generalized polynomial chaos technique in combination with the finite element method. This enabled the identification of most influencing parameters in the system. In the context of the uncertainty analysis, it is observed that the velocity obeys characteristic oscillations. In order to deepen the understanding of this phenomenon, an analytical approach is presented to evaluate the electromagnetic fields and forces while taking into account the resistive and inductive character of the moving conductor. Finally, an alternative Lorentz force eddy current testing system is proposed where the object under test is ...
Advanced modeling in Lorentz force eddy current testing
Weise, Konstantin (author) / Töpfer, Hannes / Gratkowski, Stanislaw / Dolezel, Ivo
2016-03-23
Theses
Electronic Resource
English
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