Interaction of a wedge disclination dipole with interfacial cracks

Zhang

et al. 2013

Mechanics of Materials

Self Cite

Interaction of the cooperative grain boundary sliding and migration with a crack in deformed nanocrystalline materials is investigated using the complex variable method. Effects of the two disclination dipoles produced by the cooperative deformation on the emission of lattice dislocations from the crack tip are theoretically described. The complex form expressions of the stress field and the force field are divided. The critical stress intensity factors for the first dislocation emission are calculated. Influences of disclination strength, grain size, locations of the two disclination dipoles as well as crack length on the critical stress intensity factors are discussed in detail. Results show that, the cooperative deformation has great influence on dislocation emission from the crack tip. In general, the cooperative deformation can promote the lattice dislocation emission from the crack tip, thus improve the toughness of the nanocrystalline materials.

“…(8) and (9) into formula (1), Eqs. (9) and (10) into formula (2), referring to the work in Muskhelishvili [31], Fang et al [33] and Liu et al [34], the complex potentials…”

Section: Model and Problem Formulationmentioning

confidence: 99%

Effect of cooperative grain boundary sliding and migration on emission of dislocations from a crack tip in nanocrystalline materials

Feng

Zhang

et al. 2013

Mechanics of Materials

Self Cite

“…with the tips at points a j , b j lie along the interface (x-axis) between two materials, and L is the union of the crack segments L j while L is the remainder of interface representing the complete connection part of the two kinds of material. The boundary conditions of the displacement and stress for the present problem can be expressed as follows [40]:…”

Section: Problem Formulationsmentioning

confidence: 99%

“…Without loss of generality, we assume that the two ends of the crack are located at a 0 and b 0 on the interface. Adopting the results in the work of Fang and using the principle of superposition, the solutions to the interaction between a wedge disclination quadrupole in the upper half plane and a collinear interface crack can be obtained as [40,41] Φ ω…”

Section: Problem Formulationsmentioning

confidence: 99%

Effect of special rotational deformation on dislocation emission from interface collinear crack tip in nanocrystalline bi-materials

Feng

et al. 2016

Acta Mech

The work is devoted to investigate the interaction between the special rotational deformation and interface collinear cracks in nanocrystalline bi-materials. As an illustrative example, the effect of the disclination quadrupole produced by the special rotational deformation on the emission of lattice dislocation from a finite interfacial crack tip in nanocrystalline bi-material is explored theoretically using the complex variable method. The complex form expression of dislocation force and the critical stress intensity factors for the first edge dislocation emission under remote mode I loadings and mode II loadings are deduced. And the influences of material properties, grain size, disclination strength, disclination location and orientation, special rotational deformation orientations, and crack length on the critical stress intensity factors are discussed in detail. The results show that the special rotational deformation and the relative shear modulus of the upper the lower half plane have great effect on the lattice dislocation emission from the interface collinear crack tip.

“…(6)- (8) and solving the boundary value problems defined by Eqs. (9) and (10), the complex potentials F 1 (z) and F 2 (z) in different regions can be obtained…”

Section: Problem Formulation and Solutionsmentioning

confidence: 99%

“…The stress and electric displacement fields, crack opening displacement and electric potential and piezoelectric stress intensity factor are obtained. Recently, Fang et al [8] investigated the problem of the interaction of a wedge disclination dipole with interface cracks. However, no work was done on the problem of a dislocation dipole interacting with an interface crack.…”

Section: Introductionmentioning

confidence: 99%

Interaction of a dislocation dipole with a mode III interface crack

Jin

Liu

2007

Acta Mech. Solida Sin.

Interaction between a screw dislocation dipole and a mode III interface crack is investigated. By using the complex variable method, the closed form solutions for complex potentials are obtained when a screw dislocation dipole lies inside a medium. The stress fields and the stress intensity factors at the tip of the interface crack produced by the screw dislocation dipole are given. The influence of the orientation, the dipole arm and the location of the screw dislocation dipole as well as the material mismatch on the stress intensity factors is discussed. The image force and the image torque acting on the screw dislocation dipole center are also calculated. The mechanical equilibrium position of the screw dislocation dipole is examined for various material property combinations and crack geometries. The results indicate that the shielding or anti-shielding effect on the stress intensity factor increases abruptly when the dislocation dipole approaches the tip of the crack. Additionally, the disturbation of the interface crack on the motion of the dislocation dipole is also significant.