Comparing Stress Gradient and Other Concepts for Fatigue Analysis of Notched Components

Fatigue simulation is an essential part of the development of components and systems in the automotive and machinery industry. Weak points can be identified fast and reliable. A pure virtual optimization of the design can be performed without the need of prototypes. Only for the production release a final test is necessary. A lot of parameters influence the fatigue life as the local stress, material, surface roughness, temperature etc. Notches have the strongest impact on fatigue life since they cause an increase of the local stress. Also, the local fatigue strength is increased in notches because of a support effect from the neighboring areas. To account for this effect, several methods exist, each with their specific advantages and disadvantages. In this contribution an overview is given with brief descriptions for some common methods. The methods are compared both from a theoretical and practical point of view. Especially for the stress gradient method an improvement is presented to obtain more accurate results.