Skip to main content Accessibility help
×
Home

Some aspects of forces and fields in atomic models of crack tips

  • R.G. Hoagland (a1), M.S. Daw (a2) and J.P. Hirth (a1)

Abstract

This paper examines the stresses and displacement gradients in atomistic models of cracks based on an EAM potential devised for aluminum. Methods for computing these quantities are described. Results are presented for two models differing in terms of the orientations of the crack relative to the crystal, a [100] (010) orientation that behaves in a brittle fashion and a [111] (110) orientation that emits partial dislocations prior to extending. Both models display lattice trapping. The stresses in the brittle crack model are compared with the linear elastic prediction and found to be in remarkably good agreement to within distances of about one lattice parameter of the crack tip and at the free surface where contributions from sources other than strain energy (e.g., surface tension) influence the results. Similar results are observed for the ductile model until dislocation emission occurs. The largest stresses that develop just prior to crack extension or dislocation emission are used to estimate the ratio of theoretical tensile strength to shear strength in this material. Eshelby's conservation integrals, F and M, are also computed. F is found to be essentially contour independent and in agreement with the linear elastic prediction in both models until dislocation emission occurs, at which point a large screening contribution arises from the emitted partials. The contour size dependence of M reveals some interesting features of the crack tip including a slight wobble of the crack tip inside its potential well with changing applied K and the existence of forces acting to move the crack faces apart as blunting occurs.

Copyright

References

Hide All
1.Kelly, A., Tyson, W. R., and Cottrell, A. H., Philos. Mag. 15, 567 (1967).
2.Rice, J. R. and Thompson, R., Philos. Mag. 29, 73 (1974).
3.Sinclair, J. E. and Fletcher, R., J. Phys. C 7, 864 (1972).
4.Eshelby, J. D., in Progress in Solid State Physics, edited by Seitz, F. and Turnbull, D. (Academic Press, New York, 1956), Vol. 3, p. 79.
5.Hoagland, R. G., Daw, M. S., Foiles, S. M., and Baskes, M. I., in Atomic Scale Calculations of Structure in Materials edited by Daw, M. S. and Schluter, M. A. (MRS publ. 193, Pittsburgh, PA, 1990), p. 283.
6.Hoagland, R. G., Daw, M. S., Foiles, S. M., and Baskes, M. I., J. Mater. Res. 5, 313 (1990).
7.Rice, J. R., in Fundamentals of Deformation and Fracture, edited by Bilby, B. A., Miller, K. J., and Willis, J. R. (Cambridge University Press, New York, 1975), p. 33.
8.Hirth, J. P., Hoagland, R. G., and Popelar, C. H., Acta Metall. 32, 371 (1984).
9.Hoagland, R. G., Gehlen, P. C., and Hirth, J. P., Philos. Mag. 34, 413 (1976).
10.Sinclair, J. E., Hirth, J. P., Gehlen, P. C., and Hoagland, R. G., J. Appl. Phys. 49, 3890 (1978).
11.Fautozzi, G., Eshouf, C., Benoit, W., and Ritchie, I. G., Prog. Mater. Sci. 27, 311 (1982).

Some aspects of forces and fields in atomic models of crack tips

  • R.G. Hoagland (a1), M.S. Daw (a2) and J.P. Hirth (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed