Determining fatigue life of bent and tensioned elements with a notch, with use of fictitious radius

Abstract

The work presents verification of Neuber's fictitious radius method, used in fatigue life calculation of notched elements and welded joints. Stress values, calculated according with fictitious radius method, were compared with smooth specimens Basquin fatigue curves, and number of cycles was read. However, obtained calculated number of cycles of fatigue life does not correspond to experimental fatigue life, especially in a low cycle fatigue range. Hence, different equivalent microstructural length values were calculated for different loading levels. It was observed that equivalent microstructural length depends on loading level and type of loading. Finally, equivalent microstructural length was presented in a linear regression equation, as dependant on loading level and its relation to yield strength.

An extrapolation method to determine the effective notch stress in welded joints

“…The subject of a suitable notch radius is still an ongoing debate despite the satisfactory results observed in the experiments. Some researchers 10,[23][24][25][26][27][28] argue that the notch radius should be a function of geometry (e.g., weld size and/or plate thickness) instead of being fixed at 1 mm.…”

Non‐local line method for notched elements with use of effective length calculated in an elasto‐plastic condition

“…However, as demonstrated by, 25,27,28 this zone depends on the level and type of loading. However, as demonstrated by, 25,27,28 this zone depends on the level and type of loading.…”

“…Both the replacement value of the microstructural length and many other known lengths determining the fatigue zone are represented as constants by scientists. However, as demonstrated by, 25,27,28 this zone depends on the level and type of loading. This is an important observation, because stress calculations are usually performed for the elastic material model in some studies, and there is no clear determination of the number of cycles to crack initiation.…”

“…13,24,25 In the paper, 26 the researchers used Neuber's method for mixed load. 13,24,25 In the paper, 26 the researchers used Neuber's method for mixed load.…”

“…The fatigue life of notched components or welds is often calculated using the Neuber's fictitious radius method. 13,24,25 In the paper, 26 the researchers used Neuber's method for mixed load. This method enables to replace the non-local line method where the microstructural length ρ* is used, and averaging is performed according to equation…”