AFRL-RZ-WP-TP-2009-2209 ROLLING CONTACT FATIGUE LIFE AND SPALL PROPAGATION CHARACTERISTICS OF AISI M50, M50 NiL, AND AISI 52100, PART II‒STRESS MODELING (PREPRINT) Nagaraj K. Arakere, Nathan Branch, George Levesque, Vaughn Svendsen, and Nelson H. Forster Mechanical Systems Branch Turbine Engine Division OCTOBER 2009 Approved for public release; distribution unlimited. See additional restrictions described on inside pages STINFO COPY AIR FORCE RESEARCH LABORATORY PROPULSION DIRECTORATE WRIGHT-PATTERSON AIR FORCE BASE, OH 45433-7251 AIR FORCE MATERIEL COMMAND UNITED STATES AIR FORCE