PSI - Issue 60

Rosy Sarkar et al. / Procedia Structural Integrity 60 (2024) 75–92 Rosy Sarkar/ StructuralIntegrity Procedia 00 (2019) 000 – 000

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the mean of yield stress and ultimate tensile stresses [Reddy and Swamidas (2014)]. Accordingly, the average flow stress values for SS 316 LN, at room temperature and 600 ℃ are 433 MPa and 263 MPa, respectively. 4.2.1 Elasto-perfectly plastic analysis at room temperature and 7 bars pressure Elasto-perfectly plastic analysis has been carried out in ABAQUS by giving the flow stress value in the yield stress corresponding to zero plastic strain in the property module. Displacements increasing and decreasing with time have been created in the amplitude for various number of cycles, which is taken as cyclic loading. A case of cyclic loading with 3 cycles of 20 mm displacement is shown in Figure 12. The total time is given in the step module. A constant pressure of 7 bars is maintained for all the values of displacements considered. Non-linearity is considered for all the cases.

Figure 12 Plot showing an applied cyclic displacement of 20 mm for 3 cycles

The behavior of hoop stress vs total hoop strain at room temperature and 7 bars pressure with various displacements is shown in Figure 13. It is observed that there is an elastic shakedown at 20 mm displacement. Progression in the hysteresis loops is observed at 35 mm displacement and 50 mm displacement. Thus, it may be inferred that initiation of ratcheting is expected at 35 mm displacement at room temperature. Analysis has also been carried out at 25 mm and 30 mm displacements. However, significant progression in the loops has been observed at 35 mm displacement; hence, it has been presented in Figure 13.