Extent of embossing-related residual stress on the magnetic properties evaluated using neutron grating interferometry and single sheet test
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Due to the permanently increasing maximum speed of modern electric machines, the mechanical load on the electrical steel rises. The punched flux barriers of reluctance machines play an increasingly key role in the mechanical design. The weakening of the material and the notching effect can cause local failure due to centrifugal force. In this paper, a method is presented which induces residual stresses by embossing electrical steel laminations, which contribute to the guidance of the magnetic flux and cause a negligible mechanical weakening of the sheet. The aim of this paper is to demonstrate the effectiveness of these embossed flux barriers. This is achieved by using neutron grating interferometry, that allows the density of the magnetic domains to be resolved locally. Furthermore the influence of the embossing is mapped globally by single sheet tests. The finite element analysis of the forming process derives the residual stress distribution which is responsible for the measured magnetic behavior. In order to isolate the influence of the residual stress, non-embossed and stress-relief annealed specimens are used as a reference for both measurement methods.
KeywordsElectrical steel Mechanical stress Forming Embossing Production Electric drives Neutron grating Single sheet tester
Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—HA 4395/22-1; SCHU 3227/2-1; VO 1487/31-1.
- 8.von Pfingsten G, Hameyer K, Paul D (2016) Influence of axial mechanical stress on the magnetic properties of non-oriented electrical steel. In: 2016 6th international electric drives production conference (EDPC), 30 Nov–1 Dec 2016, IEEE, Nuremberg, Germany, pp 193–200. https://doi.org/10.1109/EDPC.2016.7851333
- 9.Reimann T (2017) Vortex matter beyond sans. PhD thesis, Technische Universität MünchenGoogle Scholar
- 11.Steentjes S, Rasilo P, Belahcen A, Kouhia R, Hameyer K (2016) Anisotropic model for Villari effect in non-oriented electrical steel sheets. In: Electromagnetic field computation (CEFC), 2016 IEEE conference on, IEEE, pp 1–1Google Scholar
- 12.Vandenbossche L, Jacobs S, Van Hoecke D, Attrazic E (2015) Impact of mechanical stresses on the magnetic performance of non-oriented electrical steels and its relation to electric machine efficiency. In: Transportation electrification conference and expo (ITEC), 2015 IEEE, IEEE, pp 1–6Google Scholar
- 14.Weiss H, Steentjes S, Tröber P, Leuning N, Neuwirth T, Schulz M, Hameyer K, Golle R, Volk W (2018) Neutron grating interferometry investigation of punching-related local magnetic property deteriorations in electrical steels. J Magn Magn Mater. https://doi.org/10.1016/j.jmmm.2018.10.098 Google Scholar