Application of different fatigue strength criteria to shot peened notched components. Part 1: Fracture Mechanics based approaches

摘要

Fatigue strength assessment of notched components is an essential step within their design process. It is well known that shot peening strongly increases the fatigue strength of mechanical structures. However, the contribution of shot peening to fatigue strength is generally underestimated by engineering design codes. This is due to the difficulty of defining a general fatigue design approach that is able to correctly and quantitatively consider the effect of shot peening, in terms of residual stresses, surface work hardening and surface roughness alteration. This work critically evaluates the criteria available in the literature that have been applied to shot peened notched specimens. The entire work is divided in two parts. In the first part, fatigue strength evaluation methods based on fracture mechanics concepts are applied to notched shot peened specimens tested under different fatigue loading conditions. The second part, on the other hand, studies two recognized local stress approaches. Comparison of the results highlights the restrictions of each approach and the field in which it can be successfully applied; where possible, appropriate corrections were introduced in order to obtain a better agreement with the practical condition and the experimental data.