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Analysis of stress intensity factors for a pair of edge cracks in semi-infinite medium with distributed eigenstrain

Afsar A. M., Ahmed S. R.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 2

269-287

EN

This study analyzes stress intensity factors for a pair of edge cracks in a semi-infinite medium with a distribution of eigenstrain and subjected to a far field uniform applied load. The eigenstrain is considered to be distributed arbitrarily over a region of finite depth extending from the free surface. The cracks are represented by a distribution of edge dislocations. By using the complex potential functions of the edge dislocations, a simple effective method is developed to calculate the stress intensity factor for the edge cracks. The method is employed to obtain some numerical results of the stress intensity factor for different distributions of eigenstrain. The numerical results reveal that the stress intensity factor of the edge cracks is significantly influenced by the magnitude as well as distribution of eigenstrain within the finite depth. The eigenstrains that induce compressive stresses at and near the free surface of the semi-infinite medium reduce the stress intensity factor that, in turn, enhances the apparent fracture toughness of the material.

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Load range influence of a short propagating edge crack using the discrete dislocation technique

Hansson P., Melin S.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2005

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z. 82

107-114

EN

The influence of different load cycles on the growth of a short edge crack has been studied using a discrete dislocation technique. The external boundary is modeled with dislocation dipole elements and the plasticity is modeled by discrete dislocations. The crack is located within one grain in a bcc material, and is assumed to grow through a single shear mechanism, due to nucleation and annihilation of discrete dislocations along preferred slip planes. It was found that the applied maximum load in the cycle strongly affected the growth behavior of the crack, both in the case of constant minimum load and the case of constant load range.

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High frequency solution of elastodynamic stress intensity factors due to the diffraction of plane longitudinal wave by an edge crack in a semi-infinite medium

Pramanik R. K., Pal S. C., Ghosh M. L.

Journal of Technical Physics

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2002

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Vol. 43, no 2

113-132

EN

A harmonic in time, plane longitudinal wave is incident on a half-space containing a vertical edge crack. Both the incident field as well as the scattered field have been decomposed into symmetric and antisymmetric fields with respect to the plane of the crack, so that the problem is reduced to the boundary value problem for a 90° wedge. In both the symmetric and antisymmetric problem, incident body waves are at first diffracted by the edge of the crack. For a high frequency solution, the diffracted body wave rapidly decreasing after a few wave-lengths, the significant part of the diffracted wave is the Rayleigh wave which is reflected back from the corner of the wedge giving rise to a Rayleigh wave diffracted by the crack tip. This process of reflection of surface wave from the corner of the wedge and subsequent diffraction by the crack tip continues. Considering the contribution from the incident body waves and all the reflected Rayleigh waves, the stress intensity factors have been determined and their dependence on the frequency and on the angle of incidence has been depicted by means of graphs.