Thermomechanical Multi-Phase Simulations with Local Calculation of Material Properties to Predict and Minimize Warpage of Casting Components

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Andreas Bührig-Polaczek

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+49 241 80 95880

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The precisely tailored production of casting components contains great economic potential and forms the foundation for resource-efficient production. Despite the high niveau of casting production, established casting manufacturing processes do not yet offer the possibility to do meet this criterium for quality with targeted control possibilities in the production process. Solidification during casting is a complex process involving an interplay of physical phenomena on several scales . Large and local structural and property differences result through the interplay of thermal transport and other solidification mechanisms .

The overall goal of this subproject is to accurately predict and control the defects such as distortion and hot cracking appearing in casting processes, using numerical modelling and simulation. This is to be achieved by recording the properties' dependencies (elasticity modul e, permeability etc.) and to express them in microstructure controls, to model the local material properties, and to directly link them with the macroscopic, thermomechanical multi-phase simulation, so that it is possible to quantitatively predict warpage.

The solidification models developed in the fir st phase and the empirical heat transfer models enabled the quantification of the heat transfer with tempering for the experiments performed and are now generally applicable with the help of a newly developed physical heat transfer model. The hot cracking criteria developed and implemented in the second phase reliably identify the areas of occurrence of these defects in the component, and initial approaches for possible thermal and geometric compensation strategies were developed in the composite as well as through the numerical integration of heating layers. The criteria and compensation predictions will be extended to a multiphase approach in the third phase to further increase the precision of prediction and compensation and to physically represent the un derlying mechanisms of thermomechanical interactions. Furthermore, the development of a multiphase approach will make it possible to directly incorporate microstructure simulation results such as permeability, thus deepening the cooperation within the SFB. The precision of casting components can be quan titatively determined in advance with the models that are to be developed. This is not currently possible or rather restricted with known models, which lack calculated conditions and partially have insufficiently known framework conditions and properties.

Accordingly, through the combined application with the opt imization approaches that are to be developed, process framework conditions like superficial cooling channel direction and the influence of thermal transitions and mould geometries can be quantitatively determined in advance for precise casting production.

  Figure 1 Overview of the goals of the subproject Copyright: © SFB 1120 Figure 1 Overview of the goals of the subproject   Figure 2 Simulation set-up for F-component. Copyright: © SFB 1120 Figure 2 Simulation set-up for F-component.   Figure 3 Hot tearing tendency according to RDG criterion Copyright: © SFB 1120 Figure 3 Hot tearing tendency according to RDG criterion   Figure 4 Shrinkage and deformation inside the F-mould Copyright: © SFB 1120 Figure 4 Shrinkage and deformation inside the F-mould