3D Multilevel Modeling of Surface Roughness Influences on Hole Expansion Ratios

Abstract

The steel grade DP1000 is widely used in various industrial application fields. Its mechanical properties satisfy basic requirements in terms of strength and global formability due to the tailored microstructure composed of ductile ferrite and hard martensite. Nevertheless, the edge crack sensitivity of dual‐phase steels is still of interest. For its evaluation, hole expansion tests have become a standard experimental approach. Finite element simulation is a tool that further supports the assessment of edge crack resistance by providing insights into local stress and strain fields at the formed edges during hole expansion tests. However, there are still discrepancies between the experiments and simulations in terms of force–displacement curves and hole expansion ratios due to several factors including the hole edge surface condition. To overcome these discrepancies, this work proposes a 3D multiscale simulation strategy to quantify this factor under a complex loading case and to include it into the simulation approaches. The workflow is sufficiently general to handle arbitrary load cases. Compared with state‐of‐the‐art ductile damage mechanics simulations, the accuracy of the simulations is significantly improved.