PSI - Issue 26

Gonzalo M. Dominguez Almaraz et al. / Procedia Structural Integrity 26 (2020) 20–27 Almaraz et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 6. (a) Detail of pre-corrosion at the specimen neck section, (b) Numerical pits.

Figure 7. Stress concentration on pre-corroded specimen loaded with 47  m of displacement at the specimen ends.

• SIF is evaluated using σ y , obtained by numerical simulation . • Approximation of the plastic zone is obtained by: r p = (1/2  ) (K IC /C σ yield ) The biaxial stress field around the crack tip can be expressed as: = √2 2 (1 − 2 3 2 ) , = √2 2 (1 + 2 3 2 ) The normal stress  y is taken to evaluate the SIF close to the crack tip with  = 0, which leads to: = , =0 √2 The minimum value for r is taken as the radius for the plastic zone calculated with r p : = 2 1 ( ( ) ) 2 = 2 1 ( 1.732 9 6 1035 ) 2 = 0.000456 This value is assumed as constant during crack propagation. The numerical evaluation of SIF with the crack propagation was as follows: • Determine the normal stress  y ,  =0, by numerical simulation, 2 , with K Inconel 718 (96 - 110 MPa (m) 0.5 ), σ

IC the fracture toughness of

yield its yield stress (1035 MPa), and C the plastic constraint factor: C = (3) 1/2 .

(a)

(b)

(c)

• Evaluation of the corresponding stress intensity factor by equation (b), • Compute the crack extension and the incremental crack surface construction, • Re-mesh boundary,