Numerische Simulationen der Deformations- und Versagensvorgänge von Mg-Druckgussteilen unter Berücksichtigung inhomogener Materialeigenschaften

• Numerical simulations of deformation and failure processes of Magnesium die-cast components taking into account inhomogeneous material properties

Funke, David; Bührig-Polaczek, Andreas (Thesis advisor); Feikus, Franz-Josef (Thesis advisor); Röth, Thilo (Thesis advisor)

Aachen : Gießerei-Institut der RWTH Aachen (2023)
Book, Dissertation / PhD Thesis

In: Ergebnisse aus Forschung und Entwicklung 36
Page(s)/Article-Nr.: 1 Online-Ressource : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2023

Abstract

Multi-material structures based on die-cast components are increasingly used in car bodies. Castings provide a great design flexibility and allow to adapt their shape to the expected loading conditions under minimal material usage. Magnesium alloys offer further lightweight potential due to their low density. During product development the brittle material behavior of these alloys must be taken into account, with regard to the passive vehicle safety, since in traffic accidents the castings are exposed to high plastic deformations up to material failure. Using numerical simulations, potential strength problems of the castings can be identified and optimization measures investigated. This requires a high accuracy of the simulation results, which is mainly dependent on the representation of the geometry and the characterization of the material properties in the simulation model. During the die casting process, the conditions differ locally and depend on many factors. A distribution of these conditions inevitably results in a variation in the material properties, since the process and solidification conditions influence the microstructure of the alloy and the microstructure in turn defines the resulting mechanical material properties. Inhomogeneous distributions of properties influence the casting's deformation and failure behavior when it is exposed to external loads. A simulation model based on homogeneous material properties is not able to reproduce such relationships and is therefore limited in its accuracy. This thesis has an interdisciplinary focus on the improvement of numerical simulation models, used for magnesium castings. A main aspect is the material modeling, since a higher accuracy of the simulation results should be achieved by taking into account inhomogeneous material properties. This requires an understanding of the present distributions, which are determined by means of experimental investigations on a generic casting. Local material properties are taken into account by mapping casting simulation results to the FEA-model at first. Based on the results, such as local temperatures and flow lenghts, mechanical material properties are calculated using empirical correlation functions. The resulting material properties are finally used in the subsequent FE-analysis. The challenge in linking the process with the structural simulation is to bring the casting simulation results into a suitable relationship with the mechanical material properties.

Institutions

• Division of Materials Science and Engineering [520000]
• Chair for Foundry Science and Foundry Institute [526110]