Dr. David Potyondy is the Chief Scientist at Itasca Consulting Group, Inc., Minnesota, USA. He received his B.Sc. in Civil Engineering at University of Minnesota. He completed M.S. and Ph.D. degrees at Cornell University. Dr. Potyondy has developed and applied both continuum and discontinuum models to represent damage and flow processes on both a macro- and a micro-scale. He has directed development of the PFC codes, has developed the structural-element logic in the FLAC3D code and has developed novel techniques for applying micro-mechanical discontinuum models to fracture-related boundary-value problems, including the prediction of excavation damage produced by stress, temperature and stress corrosion.