THE fracture mechanics of piezoelectric materials is extensively studied under static mechanical or electrical loads['-41. However, the failure of practical smart structure always happens under dynamic loads, so it is urgently needed to study the fracture dynamics of piezoelectric materials. The dynamic Green's functions for anisotropic piezoelectric materials were proposed by orris'^]. The dynamic representative formulas and the fundamental solutions were presented by Khutoryansky and ~osa'~] for piezoelectric materials. The present work was carried out on the dynamic fracture of piezoelectric materials under antiplane impact and a closed form solution was obtained. As the effect of time is omitted, i. e. t tends to infinity, the present results will be reduced to the static ones"]. 1 Dynamic antiplane fracture mechanics of piezoelectric materials The antiplane crack of length 2a in an electric material under remote stress and electric displacement impacts can be decomposed into the uniform antiplane stress field and inplane electric displacement and a central crack of length 2a under antiplane stress impact r, = - r" H( t ), and the inplane electric displacement impact D, = - Dm H( t ) . The singularities of the present problem coincide with the latter one, where the boundary condition can be written as rZy = - rmH(t), Dy = - DCOH(t), 1x1 a. (lb) The dynamic antiplane governing equations for piezoelectric material can be written as C,,V~W + e1sv2$ = pa2~/at2, (2a) els~2w - E~~v~# = 0. (2b) In the above equation, the body force other than inertia and the free charge are omitted. The antiplane constitutive relations for piezoelectric material arec6] rz, = ~,,a~/a~ + e,,a+/a~, r, = c44aw/ay + elsa#/ay, (3) n, = e,,aw/a~ - ~~~a$/a~, D, = elsawlay - ~~~a#/a~, (4) where c4,, e E are, respectively, the elastic modulus, piezoelectric constant and dielectric constant of the antiplane piezoelectricity ; r, , r, , D, , Dy are, respectively, the antiplane