PSI - Issue 60

D. Sen et al. / Procedia Structural Integrity 60 (2024) 44–59 Deeprodyuti Sen/ Structural Integrity Procedia 00 (2024) 000 – 000

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The procedure described above uses the stress distribution obtained from an elastic analysis. The engineering process zone method, however, can also be used with stress distribution obtained from elastic, elastic-plastic and visco-plastic analyses. 3. Numerical implementation and Validation The Engineering Process Zone model for estimation of threshold peak stress for initiation of DHC from a blunt flaw, described in section 2, is numerically implemented in an in-house code named ZIPTAS ( Zi rconium P ressure T ube As sessment). Two different types of blunt flaws resulting from Bearing Pad Fretting and Debris Fretting, as shown in Fig.2 and Fig.3 respectively, defined in the CSA Standard (2016), are analysed. The CSA Standard (2016) has provided numerical values of the threshold peak stress for both DFF and BPFF. These results were utilized to validate the implementation of process zone model in our in-house code ZIPTAS. The material parameters used in our validation studies are provided in Table 1.

Figure 2 : A schematic of Bearing Pad Fretting flaw

Figure 3: A schematic of Debris Fretting flaw

Table 1. Material Parameters used in Validation Studies given in Scarth (2002) S. No. Geometry and Material Parameter Values

1. 2. 3. 4. 5.

K IH p c

4.5 MPa√m 450 MPa

E υ w

95 GPa

0.4 4 mm