PSI - Issue 39

Georg Schnalzger et al. / Procedia Structural Integrity 39 (2022) 313–326 Author name / Structural Integrity Procedia 00 (2019) 000–000

320

8

Fig. 7. Numerical predictions of crack propagation in FCG experiment for undeformed R260.The shear stress amplitude and superimposed axial stress is varied. (a) Stress intensity range Δ K and (b) crack growth angle α determined for the maximum stress intensity factor K max .

3.2. Fatigue crack growth experiments In Fig. 8 the results from the FCG measurements for R260 in the undeformed and pre-deformed state are presented. Fig. 8 (a) and (c) depict the applied loads in terms of the cyclic shear stress amplitude Δ τ ( R = 0.3) and superimposed static axial stress σ axial . Fig. 8 (b) and (d) present the evolution of the crack length 2 a determined periodically from optical micrographs of the specimen surface. Table 3 summarizes details regarding the deformation state, FCG specimen geometry, pre-fatigue mode, maximum applied shear stress and length of the coplanar crack propagation relevant for the FCG experiments.

Fig. 8. Overview on FCG measurements with pearlitic rail steel R260: applied loads for (a) the undeformed ( γ = 0) and (c) pre-deformed state ( γ ~ 3.5) as well as measured crack lengths for the (b) undeformed and (d) HPT pre-deformed state.