Bifurcations of a plane crack front growing quasistatically in an elastic space

Using variational-asymptotic models of force and energy criteria, situations are found in which bifurcations of the form of the front accompanying the quasistatic propagation of a plane crack in an elastic isotropic space are possible. Two types of bifurcations are revealed for a circular crack in the case of axisymmetric loading: fluctuation of the centre of the crack while preserving its circular form and distortion of the front due to the formation of two or a larger number of “lobes”.