PSI - Issue 71

Prakash Bharadwaj et al. / Procedia Structural Integrity 71 (2025) 26–33

29

= ∑ =1 = (23 : )

(4)

1 2

(5) Where, and were calibrated from uniaxial low cycle fatigue test at RT (25 °C) and 300 °C for 1% axial strain amplitude [Kumar et al. (2019)]. The calibrated material parameter, at RT and 300 °C are listed in Table 2.

Table 2. Material constants for Chaboche Model Temperature 0 (MPa) 1 1 2 2 3 3 RT 224 120000 1650 24000 238 2200 1 300 °C 300 75000 1480 20000 258 2000 1

Fig. 2. Principle back stress (X 22 ) contour for R = 0.1, crack size = 23.02 mm and 300 °C at (a) maximum load and (b) minimum load

3.

Plastic zone size calculation

(a) (b) Fig. 3. (a) Back stress variation with distance from crack tip and (b) typical contour of CPZ and MPZ at RT for crack size of 23.02 mm