PSI - Issue 47

Alexander Ilyin et al. / Procedia Structural Integrity 47 (2023) 290–295 A. Ilyin and Y. Pronina / Structural Integrity Procedia 00 (2019) 000–000

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Figure 4 shows the dependency of the service life, t* , of the toroidal shell on the initial relative stress σ 1 to the ultimate stress) for different pressures p . Various values of the initial stress σ 1 σ 1 0 / σ* = const, a toroidal shell loaded with a higher pressure has a greater lifetime. This is due to the fact that at σ 1 0 / σ* = const, shells under the higher pressure have a greater thickness. 0 / σ* (related 0 for each curve were obtained by variation of the initial shell thickness h 0 = r i – r o , other parameters being fixed, R = 2 r o . As one can see, at

Fig. 4. The dependency of the service life of the toroidal shell on the initial relative stress.

5. Conclusion The problem of assessment of the service life of a toroidal shell subjected to internal mechanochemical corrosion under pressure was considered. The space and time steps must be chosen carefully to avoid mesh-sensitivity of the solution. It was observed that relatively strong non-uniformity of the stress distribution leads to localization of the corrosive wear, when the chosen model of the corrosion kinetics doesn’t hold as well. Moreover, localization of corrosion in sufficiently thick-walled shells occurs before any of the critical conditions (reaching the maximum allowable stress or the minimum allowable thickness) is met. The analysis showed that the service life of the toroidal shell should be determined by the dissolution of the wall in the vicinity of the points closest to the shell axis. It was also confirmed that the solution for the toroidal shell tends to the solution for a cylindrical pipe as the distance parameter R of the torus increases, other parameters being the same. Calculations revealed that at a fixed initial safety coefficient, a toroidal shell loaded with a higher pressure has a greater service life due to the fact that under such conditions, shells under the higher pressure have a greater thickness. Acknowledgements This work was supported by the Russian Science Foundation, grant No 21-19-00100, https://rscf.ru/project/21-19-00100/. References

Abakarov, A., Pronina, Y., 2022. Environmentally Assisted Growth of Multiple Cracks Grouped in Stacked Configurations. Procedia Structural Integrity 42, 1046-1053 doi: 10.1016/j.prostr.2022.12.132