Interaction of moving interface collinear Griffith cracks under antiplane shear

The interaction between three moving collinear Griffith cracks under antiplane shear stress situated at the interface of an elastic layer overlying a different half plane has been studied. Fourier transform and finite Hilbert transform techniques have been employed to solve the problem. Approximate analytical expressions for stress intensity factors at the crack tips have been derived for large thickness of the elastic layer. Numerical results connected to the interaction effect have also been obtained. Depending on the spacing of the cracks, their common velocity of propagation and the depth of the layer, occurrence of shielding and amplification phenomena of the cracks have been noticed.