PSI - Issue 57

Tobias Pertoll et al. / Procedia Structural Integrity 57 (2024) 250–261 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 1. (a) Deep rolling simulation model; (b) Chaboche material model for 34CrNiMo6; (c) Graphical sequence of the simulation procedure; (d) Example of simulation result For the presented investigation, the most influential deep rolling parameter will be investigated. The numerical investigation of the influence of deep rolling parameters on the introduced residual stress distribution presented in (Pertoll et al. 2023b) shows that the deep rolling force has the most significant effect. Therefore, the simulation process is repeated with four different deep rolling forces using the simulation model presented above, whereas the deep rolling forces 5 kN, 10 kN, 15 kN and 20 kN are defined. For the further investigation, the introduced residual stress in-depth profiles are used. The resulting stresses along the evaluation path shown in Figure 1 (c) are evaluated and shown in Figure 2. The stresses in the circumferential direction ( φ -direction) are shown in Figure 2 (a) and the stresses in the longitudinal direction (Z-direction) of the railway axle are shown in Figure 2 (b). The influence of the deep rolling force is obvious. The most compressive residual stresses occur near the surface and show saturating behaviour toward higher deep rolling forces. The deep rolling force reveals a large effect on the depth impact of the process application, often referred to the depth of zero crossing of the in-depth stress profiles. While the depth of zero crossing occurs at about 1.75 mm with an applied deep rolling force of 5 kN, the depth of zero crossing increases to over 3.5 mm with the used deep rolling force of 20 kN. Underneath, compensating tensile residual stresses occur. The largest tensile residual stresses arise at the highest deep rolling force and also the maximum tensile stress is shift to higher depth. The colour scheme of the individual deep rolling forces used in Figure 2 is retained for further investigations and results. For further crack propagation investigations, only the applied residual stresses in longitudinal direction are considered as they are significant relating to the considered axial load and resulting crack growth direction.