Abstract
We investigate the elastic interaction between a moving screw dislocation and a crack. The stress intensity factor at the crack tip decreases with the increasing velocity of the screw dislocation. This implies that the shielding effect of the moving screw dislocation on crack propagation is reduced. The image force on the moving screw dislocation arising from the crack surface decreases with the increasing velocity of the screw dislocation itself. Finally, Newton's third law is not valid in the system.