Simulation of Ductile Crack Propagation in Pipeline Steels Using Cohesive Zone Modeling Written by Andrew John Dunbar, B.Eng. a thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the Degree of Masters in Applied Science, Mechanical Ottawa-Carleton Institute for Mechanical and Aerospace Engineering Department of Mechanical and Aerospace Engineering Carleton University Ottawa, Ontario August, 2011 © Copyright 2011, Andrew Dunbar