Modelling and simulation of phase transformations in elasto-plastic polycrystals
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Date
2015
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Abstract
Die vorliegende Arbeit behandelt einen neuartigen Modellierungsrahmen zur Simulation von austenitisch-martensitischen Phasentransformationen in Formgedächtnislegierungen (SMA) und TRIP-Stählen. Das Ziel der Arbeit ist die Entwicklung und Ausarbeitung eines generalisierten Modells, welches das charakteristische makroskopische Verhalten sowohl von SMA als auch von TRIP-Stahl abbildet. Als Basis für die Formulierung dient ein skalarwertiges, thermodynamisch konsistentes, auf statistischer Physik basierendes Modell für die Simulation von SMA. Im Verlauf dieser Arbeit wird das Modell in affine und nicht-affine Microsphere-Formulierungen eingebettet um das polykristalline Materialverhalten abzubilden und um die Simulation dreidimensionaler Randwertprobleme zu ermöglichen. Darüberhinaus wird eine Kopplung an Plastizität vorgestellt, welche zusätzlich die Abbildung des Verhaltens von TRIP-Stahl ermöglicht. Abschließend wird die Implementierung eines dreidimensionalen Phasentransformationsmodells für finite Deformationen mit dem Fokus auf repräsentative Transformationsrichtungen in einem thermo-elastoplastischen Framework gezeigt.
In this work, a new framework for the simulation of shape memory alloys (SMA) and TRIP steels undergoing martensite-austenite phase-transformations is introduced. The goal is the derivation and elaboration of a generalised model which facilitates the reflection of the characteristic macroscopic behaviour of SMA as well as of TRIP steels. The foundation of the overall formulation is a scalar-valued, thermodynamically consistent, statistical physics based model for the simulation of SMA. As this work proceeds, the model is implemented in affine and non-affine micro-sphere formulations in order to capture polycrystalline behaviour and to simulate three-dimensional boundary value problems. Moreover, a coupling to plasticity is introduced, additionally enabling the capturing of the macroscopic behaviour of TRIP steels. Finally, the implementation of a three-dimensional finite-deformation phase-transformation model that focuses on representative transformation directions is elaborated in a thermo-elastoplastic framework.
In this work, a new framework for the simulation of shape memory alloys (SMA) and TRIP steels undergoing martensite-austenite phase-transformations is introduced. The goal is the derivation and elaboration of a generalised model which facilitates the reflection of the characteristic macroscopic behaviour of SMA as well as of TRIP steels. The foundation of the overall formulation is a scalar-valued, thermodynamically consistent, statistical physics based model for the simulation of SMA. As this work proceeds, the model is implemented in affine and non-affine micro-sphere formulations in order to capture polycrystalline behaviour and to simulate three-dimensional boundary value problems. Moreover, a coupling to plasticity is introduced, additionally enabling the capturing of the macroscopic behaviour of TRIP steels. Finally, the implementation of a three-dimensional finite-deformation phase-transformation model that focuses on representative transformation directions is elaborated in a thermo-elastoplastic framework.
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Phasentransformationen, Plastizität, SMA, TRIP, Microsphere, FEM