Fracture Characterisation by Butterfly-Tests and Damage Modelling of Advanced High Strength Steels

authored by: Bernd Arno Behrens, Kai Brunotte, Hendrik Wester, Matthäus Dykiert
Abstract: Advanced High Strength Steels (AHSS) are widely used in today's automotive structures for lightweight design purposes. FE simulation is commonly used for the design of forming processes in automotive industry. Therefore, besides the description of the plastic flow behaviour, also the definition of forming limits in order to efficiently exploit the forming potential of a material is required. AHSS are prone for crack appearances without prior indication by thinning, like exemplary shear fracture on tight radii and edge-fracture, which can not be predicted by conventional Forming Limit Curve (FLC). Stress based damage models are able to do this. However, the parameterisation of such models has not yet been standardised. In this study a butterfly specimen geometry, which was developed at the Institute for Forming Technology and Machines (IFUM), was used for a stress state dependent fracture characterisation. The fracture behaviour of two AHSS, CP800 and DP1000, at varied stress states between pure shear and uniaxial loading was characterised by an experimental-numerical approach. For variation of the stress state, the specimen orientation relative to the force direction of the uniaxial testing machine was orientated at different angles. In this way, the relevant displacement until fracture initiation was determined experimentally. Subsequently, the experimental tests have been numerically reproduced giving information about the strain and stress evolution in the crack impact area of the specimen for the experimentally identified fracture initiation. With the help of this testing procedure, two different stress-based damage models, Modified Mohr-Coulomb (MMC) and CrachFEM, were parameterised and compared.
Organisation(s): Institute of Metal Forming and Metal Forming Machines
Type: Conference article
Journal: Key Engineering Materials
Volume: 883
Pages: 294-302
No. of pages: 9
ISSN: 1013-9826
Publication date: 2021
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Materials Science(all), Mechanics of Materials, Mechanical Engineering
Electronic version(s): https://doi.org/10.4028/www.scientific.net/KEM.883.294 (Access: Closed)
: Details in the research portal "Research@Leibniz University"

BibTeX

@article{0272345cc53e4467bdfc8718d210b3a6,
title = "Fracture Characterisation by Butterfly-Tests and Damage Modelling of Advanced High Strength Steels",
abstract = "Advanced High Strength Steels (AHSS) are widely used in today's automotive structures for lightweight design purposes. FE simulation is commonly used for the design of forming processes in automotive industry. Therefore, besides the description of the plastic flow behaviour, also the definition of forming limits in order to efficiently exploit the forming potential of a material is required. AHSS are prone for crack appearances without prior indication by thinning, like exemplary shear fracture on tight radii and edge-fracture, which can not be predicted by conventional Forming Limit Curve (FLC). Stress based damage models are able to do this. However, the parameterisation of such models has not yet been standardised. In this study a butterfly specimen geometry, which was developed at the Institute for Forming Technology and Machines (IFUM), was used for a stress state dependent fracture characterisation. The fracture behaviour of two AHSS, CP800 and DP1000, at varied stress states between pure shear and uniaxial loading was characterised by an experimental-numerical approach. For variation of the stress state, the specimen orientation relative to the force direction of the uniaxial testing machine was orientated at different angles. In this way, the relevant displacement until fracture initiation was determined experimentally. Subsequently, the experimental tests have been numerically reproduced giving information about the strain and stress evolution in the crack impact area of the specimen for the experimentally identified fracture initiation. With the help of this testing procedure, two different stress-based damage models, Modified Mohr-Coulomb (MMC) and CrachFEM, were parameterised and compared.",
keywords = "AHSS, Butterfly-Tests, CP800, Damage Modelling, DP1000, Forming Limit, Fracture Characterisation",
author = "Behrens, {Bernd Arno} and Kai Brunotte and Hendrik Wester and Matth{\"a}us Dykiert",
note = "Funding Information: The authors are much obliged to the DFG (Deutsche Forschungsgemeinschaft, German Research Foundation) for the financial support of project 405334714. Furthermore, the authors would like to thank voestalpine Stahl GmbH for the provision of the materials under investigation. ; 19th International Conference on Sheet Metal, SheMet 2021 ; Conference date: 29-03-2021 Through 31-03-2021",
year = "2021",
doi = "10.4028/www.scientific.net/KEM.883.294",
language = "English",
volume = "883",
pages = "294--302",
journal = "Key Engineering Materials",
issn = "1013-9826",
publisher = "Trans Tech Publications",
}