Micromechanical modeling of steels

Person in Charge: Hannes Erdle

Motivation:

In polycrystalline materials a significant contribution to the overall mechanical response of the material is provided by the movement of dislocations and the interactions of dislocations and grain boundaries. Gradient plasticity theories have been developed to model these micromechanical effects. Gradient-stresses are introduced in order to account for long range dislocation interactions. By introducing additional degrees of freedom, the computational cost is massively increased, compared to a classical continuum mechanical description.

The aim of subproject A20 is the development of a numerically efficient gradient plasticity theory for the simulation of the deep drawing process. The modeling of the interactions of dislocations and grain boundaries is of particular interest.

Investigations	Results
Plasticity model: Finite gradient crystal plasticity theory Comparison of finite element simulations with experimental data and analytical results Grain boundary effects: Modeling of dislocation pile-ups at grain boundaries Consideration of misorientation of slip systems	Plasticity model: Accumulated plastic slip as a numerically efficient approximated measure of the evolution of dislocations Grain boundary effects: Energetic grain boundary yield criterion Discontinuous distribution of the accumulated plastic slip with the use of an enrichment of trial functions
	Evolution of grain boundary slips with a rising homogeneous shear stress in laminate microstructure (left). Distribution of accumulated plastic slip over the length of the laminate microstructure with a grain boundary located at x=6.25µm (right). Erdle, H. & Böhlke, T. Comput Mech (2017). https://doi.org/10.1007/s00466-017-1447-7