Any experts on Griffith's fracture theory? I am studying the subject and I am having hard time finding out if the theory is valid for all possible initial crack lengths. I have heard from pretty reliable source that we must assume small crack length compared to the macroscopic length of the system. But I haven't found this restriction from the material in the web. I am building a DEM simulation model and I would like to test it against the Griffith's fracture theory but I am not sure if the simulation should produce similar values for critical stress when the length of the initial crack is not small compared to the length scale of the system.