Modeling and computation of time-continuous evolution of microstructures

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This project aims to gain a fundamental understanding of the formation and subsequent evolution of microstructures in plastic materials, and to develop comprehensive and efficient tools for their effective computation. The variational formulation in combination with appropriate relaxation concepts and efficient numerical algorithms is a key ingredient of our work.Based on our results from the first period, our proposed model for the description of laminate microstructures in finite plasticity shall be generalized into several directions and validated experimentally. An extension of the existing model to higher-order laminates will be carried out and novel approaches to account for more general, complex microstructure geometries will be addressed. The influence of several active slip systems in terms of latent-hardening interactions will be investigated. Also, the influence of lattice dislocations to constitute the laminate cell walls will be investigated with respect to their essential influence on both laminate formation and the evolution of the laminate orientation. A generalization to account for thermomechanical coupling is envisaged.Specific deformation experiments on single crystals will be performed in order to validate the extended models. The crystals will be oriented in such a way, that exactly two slip systems will be active, which will be most efficient for comparison with the theoretical results. Moreover, cyclic loading test will be performed in order to investigate more closely certain shake-down phenomena predicted by theory.