Out of phase multiaxial fatigue strength of a cast iron

The purpose of this study is to understand the behavior of a ductile iron under combined compressive axial and torsional nonproportional loading conditions. Moreover, the final aim is to propose a model to predict the multiaxial fatigue limit for defective materials. Chapter 1 is the introduction part explains briefly importance of multiaxial fatigue on structural mechanical components and methodology performed in this study. Chapter 2 covers the general review of the literature about fatigue, multiaxial fatigue and prediction models for multiaxial fatigue limit. In the Chapter 3, experimental methodology of axial, torsional and multiaxial tests, and mechanical information of the material are mentioned. Chapter 4 is the results and discussion part, all the experimental results of axial, torsional and multiaxial fatigue tests, and fracture surfaces of specimens with microstructural characterizations were published. Moreover, Papadopoulos model was applied and error percentages with respect to experimental results were calculated. Finally, Nadot’s methodology was applied in order to define the effect of defect size on multiaxial fatigue limit.