PSI - Issue 5

Valeriy Lepov et al. / Procedia Structural Integrity 5 (2017) 777–784 Valeriy Lepov et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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C Fig. 4. Stress distribution in tension: a) for sample 1, b) for sample 3, c) for sample 7.

The length of cracks revealed in weld and heat affected zone is measured by metallography using the optical microscope “Neophot - 32” and equal to 1.2 and 1.68 mm subsequently. The distance between the bottom edges of the cracks equals to 1.46 mm. The local flow stress could be calculated from microhardness values. Thus all parameters to simulate the crack growth, observe the possible path and calculate the crack velocity as an averaged discrete propagation of the crack tip are known. But another aspect of the modelling is the scale problem. The macroscopic cracks (with length of 1 mm and more) here has the same mechanical behaviour as microscopic cracks (length 1 mkm and above) so the algorithm is right, but the size of calculation zone is significantly large. So for velocity of crack the dimension factor used was equal to 100. Web-oriented visualization examples of crack growth on microdefects shown on Fig.5. Algorithm has realized by modern version of Java script language (http://iptpn.ysn.ru/hdr). Further modification of the model connected with application to a wide range of phenomena, such as accumulation of damage in porous media, materials with multiple phase transitions, including evaporation, melting and freezing, as well as the second order phase transition at lower temperature.

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Fig. 5. Java script visualization examples of crack growth on: a) micropores, b) small cracks