A test method for the determination of the cyclic material properties of electrical steel strip under strain-controlled loading

Markus Thum; Peter Haefele

doi:10.3139/120.111419

Article

A test method for the determination of the cyclic material properties of electrical steel strip under strain-controlled loading

Markus Thum and Peter Haefele

Published/Copyright: October 30, 2019

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From the journal Materials Testing Volume 61 Issue 11

Abstract

The rotors of electric machines are made of thin steel sheets, called electrical steel. Under service conditions, local strain may exceed the elastic limit i. e. for a lifetime assessment local strain might be of great significance. The main challenge for a reliable determination of the cyclic material properties of 0.3 mm thin electrical steel is to avoid buckling in the area of compression of fully reversed strain-controlled tests. Two approaches have been investigated. First, the test setup was improved and adapted to thin electrical steel specimens for which four different linear supported anti-buckling devices were developed and tested for fully reversed strain-controlled loading with the result that the best solution was a new approach using DLC coating instead of a polytetrafluoroethylene strip for reducing the friction between the specimen and the anti-buckling device. Secondly, the influence of increasing the specimen thickness by stacking single specimens through adhesive bonding is presented here.

*Correspondence Address, Prof. Dr. Peter Haefele, Laboratory of Materials and Joining Technology, Faculty of Automotive Engineering, University of Applied Sciences Esslingen, Kanalstrasse 33, D-73728 Esslingen, Germany, E-mail: peter.haefele@hs-esslingen.de

M. Eng. Markus Thum, born in 1993, studied Automotive Engineering at the University of Applied Sciences in Esslingen, graduating in 2016. Since 2016 he has been a Research Assistant at the Laboratory of Materials and Joining Technology of the Faculty of Automotive Engineering at the University of Applied Sciences Esslingen, Esslingen, Germany. His research focuses on the fatigue behavior of electrical steel strips and the influence of cut edge conditions on the fatigue lifespan of aluminum sheets.

Prof. Dr.-Ing. Peter Haefele, born in 1964, studied Mechanical Engineering at the University of Stuttgart and received his Diploma in 1993. Between 1990 and 1992 he attended the George-Washington University, Washington D.C, USA. Between 1994 and 1996 he worked at Vereinigte Aluminium Werke AG in Bonn and the Max-Planck-Institut für Eisenforschung in Duesseldorf. In 1997 he obtained his PhD, RWTH Aachen. Between 1997 and 2001 he worked at Daimler AG. Since 2001 he has been a Professor at the Faculty of Automotive Engineering at University of Applied Sciences Esslingen, Esslingen, Germany. As head of the Laboratory of Materials and Joining Technology, his work focuses on the fatigue behavior and reliability of materials and components.

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Published Online: 2019-10-30

Published in Print: 2019-11-04

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https://doi.org/10.3139/120.111419