Using a variable value of the fictitious radius to estimate fatigue life of notched elements

Abstract

The article discusses the problem related to estimating fatigue life of elements containing stress concentrators. The algorithm for estimating fatigue life presented in this work uses a fictitious ray based on the Neuber method. The proposed algorithm takes into account the variability of microstructural length, which depends on the number of failure cycles. The function thus obtained can be used to select the appropriate value for this length, which simplifies the calculation procedure needed to estimate fatigue life. In addition, this work includes an analysis of the impact of variable cutout geometry on the value of the support coefficient. As a result, it was possible to extend the application of this concept to lower fatigue life values and to structural elements with different notch geometries. The method was verified by performing experiments using elements made of three steel grades. A good correlation between calculation and experimental results was obtained.

Fatigue behavior of surfaced C45 steel

“…Robak et al introduce a model to predict the fatigue life of ring-notched elements within a range from 10 4 to 10 6 . They verified their model by carrying experiments on C45 [9]. Marcisz et al investigated the fatigue life of C45 steel under cyclic through controlled energy parameters.…”

Evaluation of the influence of mean stress on the fatigue behavior of notched and smooth medium carbon steel components through an energetic local approach

“…Poncelet 53 performed 35 fully reversal fatigue tests on smooth C45 cylinders to calibrate a multiaxial fatigue criterion for medium carbon steels (hence referred as “P‐16‐10”). Robak 54 performed a wide set of 102 constant‐amplitude fully reversed fatigue tests considering a smooth and six blunt notched cylindrical specimens (hence referred as “R‐19‐8” and “R‐12‐8‐ρ‐2α”) to investigate the effectiveness of TCD in assessing the fatigue failure of ductile metals.…”

“…Main geometrical features for C45 fatigue specimens drawn from literature 52–54 are summarized in Figure 4A. Notably, minimum diameters for all specimens are in the range d = [6, 10] mm.…”

“…Notably, minimum diameters for all specimens are in the range d = [6, 10] mm. As respect to blunt V‐notched specimens reported in Robak, 54 three different opening angles 2α [°] = {30, 50, 90} and four different notch radii ρ [mm] = {0.2, 0.3, 0.5, 0.7} were considered.…”

Effect of non-zero mean stress bending-torsion fatigue on fracture surface parameters of 34CrNiMo6 steel notched bars

“…Engineering materials with different geometries and shapes are with their nuances increasingly reflected in fatigue tests (Kowal and Szala, 2020;Ulewicz et al, 2014;Ulewicz et al, 2019;Trško et al, 2020;Wu et al, 2020;Robak, 2020). Loading generation also needs to be developed to get as close as possible to the service conditions, both by standard and a special performance of fatigue machines (Jamali et al, 2019;Rozumek et al, 2018;Saito et al, 2020;Pejkowski et al 2018).…”