As a solution we used a cohesive strength value higher than the macroscopic strength, or strength scaled down to the test volume by Weibull’s weakest link model. This is a reasonable approach, since the exact crack onset is not main topic of the model used here. To circumvent the related problems with high cohesive strength values, the theoretical strength value is also not chosen. It was found that, after a sufficient small process zone is reached, and the related brittle