PSI - Issue 18

Fokion Oikonomidis et al. / Procedia Structural Integrity 18 (2019) 142–162 Dr Fokion Oikonomidis / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 6 shows the distribution of the residual stress in the direction of the chain axis after the proof load was relieved and the notch generated. The figure shows the path for the stress profiles plotted in Fig. 7. This graph shows the residual stress being compressive at the intrados, with a significant stress concentration after the notch was generated. Then, the bending stress applied by the roller increases the stress in the region of the notch, which is close to zero when the bending load is about 870kN. If part of the bending load cycle is below 870kN, the crack is likely to be partially closed during pre-cracking.

Fig. 6. Residual stress after proof loading and notching. The white arrow shows the path for the stress profile in Fig. 7.

Fig. 7. Profile of the stress acting in the direction normal to the crack plane after the EDM notch and for various bending loads for fatigue pre cracking.