ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Application of crystal plasticity to cyclic loading and comparison to conventional plasticity

Date: 26.09.2012
Place: MSE 2012, Darmstadt, Germany

Martin Boeff
Steffen Brinckmann
Alexander Hartmaier

Fatigue is a process of multiple stages and different length scales. Although multiple continuum fracture models exist, most of them simulate on the fatigue growth of a preexisting crack, i.e. those models neglect its initiation. However, fatigue crack initiation has the dominating influence on fatigue life because 80% of fatigue life is spent in this phase. Therefore, those models cannot be used to determine the total fatigue life. To account for material evolution during the first stage, plasticity has to be considered, which evolves cyclically on a length scale which spans a few grains. This contribution compares the cyclic plasticity evolution according to conventional plasticity models to those predicted by a crystal plasticity model, which models slip events and the cyclic accumulation of plastic deformation on crystallographic slip systems. With these models a representative volume element is constructed, which consists of a ferrite matrix with pearlitic inclusions. The damage evolution under cyclic loading conditions is determined and favorable places of damage accumulationare identified.

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