PSI - Issue 51

Michael Horvath et al. / Procedia Structural Integrity 51 (2023) 95–101 M. Horvath et al. / Structural Integrity Procedia 00 (2022) 000–000

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conducted considering notched specimens with 2  = 135° and resulted in slightly conservative fatigue life values that are in correspondence to those evaluated by the presented TCD-framework, as depicted in Fig. 5.

Fig. 5. Fatigue assessment results of notched specimens (2  = 135°) based on the strain energy density concept.

Furthermore, the dependency of the control radius R c and the critical distance L M upon the number of cycles to failure N f is studied. Fig. 6 shows the relation between the two parameters in comparison to the one originally proposed by (Yosibash et al. 2004), which is given in Equation (3).

Fig. 6. Ratio between the control radius R c and the critical distance L M as a function of the number of cycles to failure N f .

Considering herein a Poisson’s Ratio for metallic materials of  = 0.3, one obtains a ratio between the control radius and the material intrinsic length of R c / a 0 = 0.845. This ratio is evaluated under the assumption, that the critical loading SED is independent of the notch opening angle in brittle materials, where the acting stress is equal to  c . As  c represents the stress at failure without the presence of a notch, the numerical analysis within this study confirms the findings of (Yosibash et al. 2004) in the low-cycle fatigue regime, where the S-N curves of notched and unnotched specimens are quite close in the low-cycle fatigue strength. 5. Conclusions The present work contributes the fatigue life assessment of imperfective cast steel components made of G12MnMo7-4+QT in the medium-cycle regime at various load ratios. A linear-elastic TCD-framework is built up and comprehensively validated for specimens of a different notch geometry. Furthermore, the methodology is extended to arbitrarily shaped spatial imperfections, leading to reasonable fatigue life estimations of experimentally derived results. Following the idea of the implemented linear-elastic framework, a strain energy density-based fatigue assessment methodology is subsequently formulated, which proposes a relationship between the control radius R c and