I am attempting to generate very small size Voronoi polygonal blocks for a rock sample. The mean grain size of the rock is 0.0001m. I have been able to build voronoi blocks of 0.002m (figure given below). However, when I further reduce the size to 0.001m (10 times higher than 0.0001m), it gets stuck and does not move further. Then I shut down the program and restart. The code is given below
When trying to calibrate a numerical simulation to laboratory behaviour, you may find that you do not need to exactly match the Voronoi block size to the grain size of the laboratory specimen, but instead also need to consider computational efficiency. The Voronoi size only needs to be small enough (relative to the sample size) to allow representative progressive failure mechanisms to occur.
I would suggest undertaking a sensitivity analysis, gradually changing your Voronoi block size and seeing the failure patterns that occur, and ensure that your chosen Voronoi block size is not controlling the failure patterns that form.
I could not agree more. I would only add that the respective joint parameters (esp. stiffnesses) should be altered accordingly with the varying Voronoi-sizes in order to reproduce a similar macroscopic response. For example, with few Voronois the effective bulk modulus of the block assembly is dominated by the bulk modulus of the grains (since you have comparatively small amount of joints), while joint stiffness dominates at higher Voronoi count.
From my experience, this does not only affect the elastic response, but the failure patterns as well. The stiffness estimation formulae in the manual are typically a good starting point.