Course contents
This course provides an introduction to the fatigue assessment of mechanical components in the presence of cracks or notches. It covers the derivation of stress fields ahead of cracks and notches using the Airy stress function and the complex potential function method (Kolosov and Muskhelishvili). Students will explore a case study on sharp V-notches under in-plane loading, focusing on the Lazzarin-Tovo analytical derivation of local stress fields based on complex potential functions and a comparison with Williams’ solution. Furthermore, the course includes the definition of Notch Stress Intensity Factors (NSIFs) and an introduction to local approaches based on the NSIF concept, specifically the averaged strain energy density (SED) and the peak stress method (PSM). Finally, these concepts culminate in the practical application of local approaches to the fatigue strength assessment of mechanical components by means of Finite Element (FE) analyses using the Ansys FE code.
Learning goals
In this course, students will learn the analytical basis of notch stress analysis. They will explore how to apply both standard methods (e.g., nominal stress) and local approaches (NSIF, SED, PSM) for the fatigue strength assessment of welded joints. Finally, students will gain practical experience in performing linear elastic structural FE analyses using Ansys.
Suggested readings
- Sadd M. H. Elasticity. Theory, Applications and Numerics. Elsevier; 2004.
- Lazzarin P., Tovo R. A unified approach to the evaluation of linear elastic stress fields in the neighborhood of cracks and notches, Int. J. Fract. 78 (1996) 3–19.
- Anderson T. L. Fracture Mechanics. Fundamentals and Applications. CRC Press; 1995.
- Lazzarin P., Zambardi R. A finite-volume-energy based approach to predict the static and fatigue behavior of components with sharp V-shaped notches, Int. J. Fract. 112 (2001) 275–298.
- Meneghetti G., Lazzarin P. Significance of the elastic peak stress evaluated by FE analyses at the point of singularity of sharp V-notched components, Fatigue Fract. Eng. Mater. Struct. 30 (2007) 95–106.
- Radaj D, Vormwald M. Advanced methods of fatigue assessment. Springer; 2012.
