Emission criterion of a screw dislocation near a semi-infinite wedge crack partially penetrating a nanoscale piezoelectric inhomogeneity with interface effect

The electro-elastic interaction between a piezoelectric screw dislocation and a semi-infinite wedge crack partially penetrating a circular nanoscale piezoelectric inhomogeneity is investigated. Using Riemann-Schwartz's symmetry principle integrated with the analysis of singularity of complex functions and the conformal mapping technique, the expressions of electro-elastic fields in matrix and inhomogeneity regions are derived explicitly. The image force, the stress intensity and electric displacement intensity factor of crack tip, as well as the critical applied stress and the critical electric displacement intensity factor for dislocation emission are discussed in detail. The results show that the positive piezoelectric screw dislocation can reduce the stress intensity factor of the wedge crack tip and shield the crack growth. If the coupling of electric displacement and positive stress at the interface is considered, the shielding effect will increase and the situation of image force will change. The most probable angle for dislocation emission is zero, and the greater the shear modulus and piezoelectric constant of the matrix, the greater the wedge crack opening angle, the more difficult for dislocation emission. In addition, the positive (negative) interface stress blocks (boosts) dislocation emission, and the existence of electric displacement at the interface makes dislocation emission more difficult.