AN ASYMPTOTIC ANALYSIS OF STATIONARY AND MOVING CRACKS WITH FRICTIONAL CONTACT ALONG BIMATERIAL INTERFACES AND IN HOMOGENEOUS SOLIDS

The plane strain and plane stress problem of a stationary or steadily moving crack with frictional sliding crack surface contact is investig ated, with emphasis on the asymptotic structure of the crack tip field s. The crack is assumed to lie along the interface of an elastic aniso tropic bimaterial with an aligned plane of symmetry, which covers spec ial cases where the bimaterial is orthotropic or isotropic, or where t he bimaterial becomes homogeneous. A full representation of the asympt otic fields around the interface crack is derived in terms of several arbitrary analytic functions, with explicit expressions for the singul ar crack tip stress and displacement fields given for a steadily propa gating interface crack in an isotropic bimaterial, which are used to p redict the direction of possible crack deviation from the interface. F or a stationary crack, the singularity of the stresses can be, in gene ral, stronger or weaker than r-1/2 (where r is the distance to the cra ck tip) depending on the loading history, while for a steadily growing crack, the singularity must be weaker than r-1/2, resulting in zero e nergy release rate at the crack tip. For bimaterials with orthotropic symmetries, the form of the singular stress field is found somewhat si milar to that of the classic mode II problem. When these types of mate rials become homogeneous, and irrespective of the amount of friction b etween the contacting crack faces, the singular crack tip fields are i dentical to those of the classic mode II problem. Hence, the solutions are also governed by the conventional stress intensity factor K(II), implying a nonzero crack tip energy release rate, which is related to K(II) in the usual manner. Implications of the above findings will be discussed.