Cohesive element approach to grain level modelling of intergranular cracking

A novelty in this work is the developed analytical expression for assessing the cohesive element response when using viscous regularization for alleviating the convergence issues. It shows that the viscous regularization should not be higher than 10% of the step time. Otherwise the delay in the damage evolution and the area underneath the traction-separation response of a cohesive element increase considerably. This is also demonstrated on a model with 500 grains where the time-evolution of the displacements in the cohesive elements is significantly more complicated compared to the linear assumption in the theoretical expression. Also, the fraction of the elastic displacements compared to the total displacements at complete failure plays a role, with a higher elastic part resulting in smaller increase of the maximum traction in the cohesive element.