Modeling intergranular cracking in polycrystalline aggregates: explicit account for grain boundaries with cohesive zone approach

Understanding and controlling early damage initiation and evolution are amongst the most important issues in nuclear power plants. Intergranular cracking has been known to occur in both austenitic steels and nickel based alloys. In this work a grain-level scale model is presented for modeling interganular cracking. Grains and grain boundaries are modeled explicitly. Grain boundary damage initiation and evolution is included by employing the cohesive zone approach. Both cohesive elements and cohesive surfaces are explored and compared. Cohesive surface approach is simpler to implement while the cohesive elements make the tracking of the damage initiation and evolution easier. The behaviour under simple isotropic elastic and more complex crystal plasticity constitutive laws for grains is studied. For the studied cases the cohesive surface approach with linear tetrahedron elements proved to be numerically much more stable compared to cohesive elements and cohesive surfaces with quadratic tetrahedron elements. For the cohesive elements and the cohesive surfaces with linear tetrahedron elements, the increase in the cohesive stiffness has basically no effect. For the cohesive surfaces with quadratic tetrahedron elements, the effect is positive at small mesh density.

SIMONOVSKI Igor;  CIZELJ Leon;  MACHINA Gangadhar;  UPLAZNIK Mihaela Irina; 

2013-09-10

iASMiRT

JRC76999

https://publications.jrc.ec.europa.eu/repository/handle/JRC76999,