Screw dislocations and an interfacial blunt crack with viscoelastic interface

This work deals with the influence of Kelvin-type viscoelastic interface on the generation of screw dislocations near the interfacial blunt crack tip in light of a pair of concentrated loads. The stress fields for dislocation and concentrated load have been obtained by using the integral transform and conformal mapping, the stress intensity factor have been studied, the image force acting on dislocation has been analyzed. The region r(b) where n screw dislocations are generated by a pair of concentrated loads and dislocation number are obtained by displacement compatibility and stress compatibility conditions of self-consistent and self-equilibrated systems. The results show that: the force acting on dislocation starts with the value that a perfectly bonded interface, then with relaxation of the imperfect interface; the shield effect for dislocation decreases as time goes by; in addition, with time elapsing, the influence of material shear modulus rate on shielding effect becomes weaker and weaker. The scale of multiplier alpha(r(b)/a) increases with relaxation of imperfect interface, the larger ratio of crack geometry c/a and the smaller ratio of shear modulus mu(1)/mu(2) Will lead the higher scale of multiplier. When mu(1)/mu(2) = 1, the screw dislocations number first increases and then decreases with relaxation of imperfect interface, in addition, it possesses the highest value at t(0) approximate to 1 and tends to vanish at t(0) = infinity. When mu(1) < mu(2), the screw dislocations number increases with relaxation of imperfect interface. When mu(1) > mu(2), the screw dislocations number first increases then decreases with relaxation of imperfect interface, and possesses the highest value at t(0) approximate to 1, the negative value are exclude from the discussion. (C) 2009 Elsevier Ltd. All rights reserved.