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

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.