Multiskalen-Simulation zur Beschreibung des Anisotropieverhaltens beim Rohrziehen
Zusammenfassung der Projektergebnisse
In tube drawing, maintaining uniform wall thickness is crucial, as eccentricity can significantly impact the quality and performance of the tubes. Managing this imperfection is challenging, but it has been shown that tilting the tube, adjusting die eccentricity, or controlling residual stresses can help improve tube precision. To gain deeper insights into the mechanisms governing deformation and anisotropy during tube drawing, a 3D-FEM model incorporating Crystal Plasticity (CP) theory was developed using ABAQUS. This model provided valuable understanding, but it initially relied on literature-based flow rule values and elastic/plastic parameters, which were imported into the Finite Element (FEM) simulations. Given that these parameters are inherently linked to microstructural features and mechanical properties at smaller scales, a multiscale approach was adopted to enhance the Crystal Plasticity Finite Element (CPFE) model. The objective of this work was to refine the existing CPFE model by integrating it with a multiscale simulation framework based on Integrated Computational Materials Engineering (ICME). The enhanced model was first tested on aluminum tubes to evaluate its applicability beyond copper. A multiscale methodology was implemented to obtain accurate parameters for the CPFE model, ensuring a more precise prediction of anisotropic material behavior. This approach linked four key length scales — electronic, atomic, micro, and meso — allowing for a comprehensive understanding of material deformation during tube drawing. Dislocation Dynamics (DD) simulations provided the hardening rule constants, enabling the calculation of anisotropic hardening parameters for both copper and aluminum. Molecular Dynamics (MD) simulations determined dislocation mobility, which served as input for DD calculations. Modified Embedded Atomic Method (MEAM) calculations yielded anisotropic elastic constants, which were essential for defining interaction potentials in MD simulations. Density Functional Theory (DFT) was used at the electronic scale to compute generalized stacking fault energy (GSFE) and analyze energy variations as a function of the lattice parameter. Ultimately, the developed framework was validated against experimental measurements, demonstrating its accuracy in predicting texture evolution and mechanical behavior during tube drawing. Moreover, this approach is designed to be adaptable to various materials, different reduction levels, and diverse tilting/offset conditions, making it applicable not only to tube drawing but also to other metal forming processes.
Projektbezogene Publikationen (Auswahl)
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Multiscale Simulation Study on the Anisotropic Behavior of Seamless Copper Tubes Processed under Varied Conditions. Journal of Manufacturing Processes, 56, 258-270.
Foadian, Farzad; Khani, Somayeh; Carradó, Adele; Brokmeier, Heinz G. & Palkowski, Heinz
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“Multiscale modeling of crystal plasticity in tube drawing process of aluminum,” Darmstadt, Sep. 27 2022.
S. Khani
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Mechanical properties of aluminum through electronic- and atomic-scale simulations. Nanomaterials and Energy, 12(2), 49-56.
Khani, Somayeh & Palkowski, Heinz
