@article{KubaschinskiGottwaltTetzlaffetal.2023, author = {Kubaschinski, Paul and Gottwalt, Albin and Tetzlaff, Ulrich and Altenbach, Holm and Waltz, Manuela}, title = {Modelling and simulation of the hardness profile and its effect on the stress-strain behaviour of punched electrical steel sheets}, volume = {54}, journal = {Materials Science \& Engineering Technology}, number = {4}, publisher = {Wiley}, address = {Weinheim}, issn = {0933-5137}, doi = {https://doi.org/10.1002/mawe.202200283}, pages = {512 -- 526}, year = {2023}, abstract = {The shear cutting of electrical steel sheets has a significant influence on the magnetic and mechanical material properties. Due to plastic deformation and strain hardening in the area of the punched edge, the electrical steel sheets exhibit a characteristic hardness profile. This study deals with the modelling of the resulting hardness profile by means of finite-element simulations. Elastic-plastic material properties are obtained from spherical nanoindentation testing as a function of the local hardness. In particular, representative stress-strain values are determined by applying Tabor's concept of indentation stress-strain curves. The choice of the appropriate stress- and strain-constraint factors is discussed with respect to the nanoindentation test setup used. Following this, the representative stress-strain values are analytically described to determine true stress-strain curves for the local assignment of different material models depending on the hardness. The implementation of the modelling approach in a finite-element simulation is presented for a punched electrical steel sheet specimen under monotonic loading. The simulation results are basically in good agreement with experimental data and confirm the expected influence on the mechanical material behaviour due to the shear cutting process.}, language = {en} } @article{KubaschinskiGottwaltTetzlaffetal.2022, author = {Kubaschinski, Paul and Gottwalt, Albin and Tetzlaff, Ulrich and Altenbach, Holm and Waltz, Manuela}, title = {Calibration of a combined isotropic-kinematic hardening material model for the simulation of thin electrical steel sheets subjected to cyclic loading}, volume = {53}, journal = {Materials Science \& Engineering Technology}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-4052}, doi = {https://doi.org/10.1002/mawe.202100341}, pages = {422 -- 439}, year = {2022}, abstract = {The combined isotropic-kinematic hardening model enables the description of the cyclic transient elastic-plastic material behaviour of steel. However, the determination of the material model parameters and understanding of their influence on the material response can be a challenging task. This study deals with the individual steps of the material model calibration for the simulation of thin electrical steel sheets under cyclic loading. Specific recommendations are made for the determination of kinematic and isotropic hardening material parameters. In particular, the isotropic hardening evolution is described by Voce's exponential law and a simple multilinear approach. Based on the multilinear approach, which allows for different slopes in the evolution of the yield surface size, an alternative calibration of the isotropic hardening component is proposed. As a result, the presence of the yield plateau in the first half cycle can be accurately captured, while convergence issues in the material model definition for numerical simulations can be avoided. The comparison of simulated load cycles with experimental cyclic tests shows a good agreement, which indicates the suitability of the proposed material model calibration for electrical steel.}, language = {en} } @inproceedings{KubaschinskiBaruthTetzlaffetal.2022, author = {Kubaschinski, Paul and Baruth, Albin and Tetzlaff, Ulrich and Altenbach, Holm and Waltz, Manuela}, title = {Untersuchungen zur Ermittlung der zyklischen Kennwerte von d{\"u}nnem Elektroblech im Rahmen der rechnerischen Lebensdauerabsch{\"a}tzung}, pages = {BF-2022-014}, booktitle = {Betriebsfestigkeit - Wissensmanagement und Methodenentwicklung entlang der Wertsch{\"o}pfungskette}, doi = {https://doi.org/10.48447/BF-2022-014}, pages = {163 -- 178}, year = {2022}, language = {de} }