PSI - Issue 21

Hakan Şahin et al. / Procedia Structural Integrity 21 (2019) 38–45 Sahin H./ Structural Integrity Procedia 00 (2019) 000 – 000

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In the analysis models, crack depth value a is taken as 1 and the other parameters are calculated depending on the case analysed, i.e., aspect ratio of surface crack ( a/c =0.25, 0.5, 1, 2, 4) and crack depth with respect to plate thickness ( a/t =0.2, 0.4, 0.6, 0.8). Also, in the models, half width of plate b is equal to half of height, h. The dimensions h and b are equal to the five times of crack length or depth, whichever is greater . A uniformly distributed axial tensile stress was applied from the upper and lower surfaces of the plate. A corner point at bottom surface was fixed in all directions, two other points are fixed in two directions and one direction only, to prevent the rigid body motion.

Figure 2: A semi-elliptical inclined surface crack in a plate loaded by remote uniform tensile loads (Ayhan, 2004).

After calculating the mixed mode stress intensity factors using FRAC3D, they are normalized using a reference K r value, which is dependent on the applied tensile load and crack length/depth. Q is the shape factor for the elliptical crack. K r and Q formulations are given in the equation by Newman and Raju (1981).

0         a Q 

K

(4)

r

1.65

a c       c a      

a c a c

1 1.464

;

1

Q

 



(5)

1.65

1 1.464

;

1

Q

 



(6)