PSI - Issue 23

Hector A. Tinoco et al. / Procedia Structural Integrity 23 (2019) 529–534 H. A. Tinoco/ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2. Von Mises stress distributions at the crack-tip for different loading levels.

Particularly, it is noted that when the force is removed completely (0 N for total unloading), the residual stresses are visible at the crack tip and these are higher than the stresses reached for 5400 N in the loading stages I and II. Therefore, the plastic zone size at the end of the unloading stage CP r can be estimated. Figure 3a presents the results of the crack opening displacement profile ( ) (0,20) y u x x m    , where x is running in the direction behind the crack tip. It is observed that in the loading stage I, the force opens the crack until 0.103 y u m   at the first one ( 0.0995 x m   ) obtained for the maximum load (23000 N). After unloading (0 N) the crack opening displacement at the first node reached its minimum 0.052 . y u m   Finally, during reloading the crack