DYNAMIC WEIGHT-FUNCTIONS FOR A MOVING CRACK .2. SHEAR LOADING

Dynamic weight functions are constructed for general time-dependent shear loading of a plane semi-infinite crack propagating with constant speed in an infinite isotropic elastic body. The use of Fourier transforms reduces the problem to the analysis of a matrix Wiener-Hopf equation. The solution of the Wiener-Hopf problem is presented. An expression is derived for the first-order perturbation to the stress intensity factors induced by a small time-dependent deviation from straightness of the crack front. The asymptotic procedure requires consideration of two terms of the asymptotic expansions of the displacement and stress tenser components in a neighbourhood of the crack front.