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A screw dislocation located outside, inside or on the interface of a parabolic elastic inhomogeneity

Wang X., Schiavone P.

Archives of Mechanics

2021

Vol. 73, nr 3

219--235

Using conformal mapping techniques, superposition and analytic continuation, we derive analytic solutions to the problem of a screw dislocation interacting with a parabolic elastic inhomogeneity. The screw dislocation can be located anywhere either in the surrounding matrix or in the parabolic inhomogeneity or simply on the parabolic interface itself. We obtain explicit expressions for the two analytic functions in the image plane characterizing the elastic fields describing displacement and stresses in the two-phase composite. Using the Peach-Koehler formula, we also obtain the image force acting on the screw dislocation. The analytic function defined in the parabolic inhomogeneity in the physical plane can be interpreted in terms of real and image screw dislocations for any location of the real screw dislocation.

Screw dislocations in piezoelectric laminates with four or more phases

Wang X., Chen L., Schiavone P.

Archives of Mechanics

2019

Vol. 71, nr 3

239--262

We present an analytical solution to the problem of a screw dislocation in a four-phase piezoelectric laminate composed of two piezoelectric layers of equal thickness sandwiched between two semi-infinite piezoelectric media. A new version of the complex variable formulation is proposed such that the 2 × 2 real symmetric matrix appearing in the formulation becomes dimensionless. Using analytic continuation, the original boundary value problem is reduced to the identification of a single 2D analytic vector function which is completely determined following rigorous solution of the resulting linear recurrence relations in matrix form. An explicit expression for the image force acting on the piezoelectric screw dislocation is obtained once the single 2 × 2 real matrix function is identified. We also discuss the solution for a screw dislocation in an N-phase piezoelectric laminate composed of N − 2 piezoelectric layers of equal thickness sandwiched between two semi-infinite piezoelectric media.

AFM studies of pits formation on KBr(1 0 0) during its dissolution by water

Pers J., Barwiński B., Grodzicki M., Ciszewski A.

Materials Science Poland

2016

Vol. 34, No. 4

863--867

The formation of etch pits along screw dislocations on KBr(1 0 0) surface during its dissolution by water is investigated by means of atomic force microscopy (AFM). Clean KBr(1 0 0) is obtained by cleavage. A weak solution of water in isopropyl alcohol is used to investigate the etching in real time. Observations of the etch pit evolution with etching time show that concentration of atomic steps on the pit walls and dissolution rate of the walls vary up to complete dissolution of the screw dislocation. The screw dislocation removal stabilizes the dissolution, resulting in constant values of atomic steps concentration on the pit walls and their dissolution rate during further etching, which continues according to the crystal dissolution stepwave model. It was found that the movement of AFM scanning tip essentially affected the etching process.

Logarithmic screw dislocation

Wesołowski Z.

Engineering Transactions

2004

Vol. 52, iss.4

297-300

Basing on linear elasticity, the displacement field uz=B[theta]lnr (in cylindrical coordinates r, [theta], z) was derived. This displacement has a jump on the half-plane [theta]=0. Stresses orthogonal to this discontinuity plane are continuous.