PSI - Issue 28

Carlos D.S. Souto et al. / Procedia Structural Integrity 28 (2020) 146–154

153

8

Carlos D.S. Souto et al. / Structural Integrity Procedia 00 (2020) 000–000

Fig. 9: J-integral contour definitions in Omicron.

4.3. Results

Obtained results for one of the crack lengths modeled ( a = 5 mm) are presented in Table 1. Results obtained present a relative di ff erence below 6%, demonstrating that these techniques can be applied straightforwardly in new finite element software solutions.

σ y w tan 1989.9

w

σ y √ π a

π a

Variables

mVCCT

J-integral

K [MPa · mm 1 / 2 ] Relative di ff erence [%]

1981.7

1980.5

1875.5, 2018.4, 2042.2

-

0.4

0.5

5.8, 1.4, 2.6

Table 1: Results comparison between analytical and numerical calculations.

5. Conclusions

The progress of computational fracture mechanics has been supported by the increase of a regular computer’s capabilities and by the new techniques that require lower computational costs. In this study, the stress intensity factor calculation is revised using a new finite element software while evaluating the implementation of two techniques: the J-integral technique (as a post-processing option) and the modified Virtual Crack Closure Technique (mVCCT). The classical problem of a finite plate with a central crack was adopted for assessment and validation of the stress intensity factor calculations. From this study, it is concluded that the implementation of the J-integral technique requires more e ff ort to define the paths and to determine the energy along that path. The mVCCT is a more straight forward calculation, just requiring that the two elements behind and in front of the crack tip are identically. Although this technique is not directly accessible in commercial software, the mVCCT is one of the best alternatives to estimate stress intensity factors in finite element models.

Acknowledgements

The presented work was carried out within the course of Computational Damage and Fracture, lectured by Professor Paulo Tavares de Castro, during the Masters in Computational Mechanics at Faculty of Engineering of the University of Porto, in this way, the first author would like to gracefully thank the Professor for the opportunity and guidance in order to develop the presented work.

References

Ingra ff ea, A. R., de Borst, R., 2017. Computational fracture mechanics. Encyclopedia of Computational Mechanics, Second Edition, Edited by Stein, E., de Borst, R., Hughes, T.J.R., John Wiley.