Publication Date


Document Type


Committee Members

Ha-Rok Bae (Committee Member), Sheng Li (Advisor), Ahsan Mian (Committee Member)

Degree Name

Master of Science in Mechanical Engineering (MSME)


The contact fatigue failure in the form of micro or macro-scale pitting is an important failure mode for rolling mechanical elements, such as bearings and gears that are widely used in the automotive, aerospace and wind turbine fields. The micro-pitting process in some cases, gradually removes the surface material through fatigue wear, altering the geometry of the contact surfaces to alleviate the contact pressure decelerating the continued pitting rate. The propagation of the micro-cracks in other cases, goes deep into the material along a shallow angle, turns parallel to the surface at a certain depth, where the maximum shear or material voids or impurities take place, and lastly turns back to the surface, forming macro-sized pits changing the geometry of the contact surface, resulting in large vibration and dynamic behavior of the mechanical components. The propagation of a crack is tightly related to the stress concentration in the vicinity of the crack tip. This study investigates the Stress Intensity Factor (SIF) of Surface Micro-cracks under Hertzian and Sinusoidal pressure distributions considering the effects of surface friction imitating the smooth and rough contact surfaces. The finite element approach is used establish the computational model and to examine the impacts of the crack length, the crack orientation, the surface friction and different type of loading on SIF.

Page Count


Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.