PSI - Issue 22

Yaroslav Dubyk / Procedia Structural Integrity 22 (2019) 275–282 Yaroslav Dubyk / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3. Equivalent von-Mises stresses [Pa] for Normal Operation conditions

2.3. Main equations SIF solutions and Limit Load solutions for through wall cracks are well-known, and taken from Zahoor (1989). Crack opening area is a more challenging problem, and is calculated according to Orynyak et al. (2012), where crack opening area (COA) is given with membrane P m  and bending M m  corrections, according to shell deformation:





2 2 l 

M



1         P m M P m 

P

A





(4)

m

E

Typically, for LBB concept Henry-Fauske flow model is used with modified parameters accounting for crack morphology Rundlan et al. (2002). A flow model is an important part of analysis, since different crack types have a great differences in friction (µ L , µ G ), bend and protrusion (n L ), flow length (K G , K GL ) parameters (see Table 3). Influence of half crack length on COA and pressure loss parameters is shown in Fig. 4. From Fig. 4(right) we can see that pressure loss due to bends and protrusions has the most significant impact, thus a special attention should be paid on IGSCC crack types (see Table 3).

Table 3. Mean and standard deviation of crack morphology parameters

Crack morphology variable

Corrosion fatigue

IGSCC

PWSCC

Mean 8.814 40.51 6.730 1.017 1.060

SD

Mean

SD

Mean 10.62 92.67 8.043 1.060 1.327

SD

µ L , (µm) µ G , (µm) n L , (mm

2.972 17.65 8.070

4.70 80.0 28.2 1.07 1.33

3.937 39.01 18.90 0.100 0.170

9.870 65.26 2.043 0.095 0.249

-1 )

K G

0.0163 0.0300

K GL