The conventional formulation used in the past for problems involving interface cracks leads to a physical contradiction: The two sides of the crack are assumed to be free of tractions in the formulation, but the crack faces are seen to overlap after the solution is constructed. This unsatisfactory feature can be eliminated by introducing contact zones at the tips of an interface crack. The present article investigates the effect of friction in the contact zones for loads that start from zero and are increased monotonically. As an application, shear loading is considered, and the problem is reduced to a singular integral equation with a Cauchy-type kernel which is solved numerically. The results show that one of the contact zones is large and that friction affects the global nature of the stress fields. The results worked out include also the stress intensity factors, crack opening displacement, and the pressure distribution in the larger contact zone.
R~SUM~
La formulation habituelle utilis6e dans le pass6 pour des probl~mes de fissures interfaciales conduit h une contradiction physique: Les deux l~vres de la fissure doivent ~tre libres de contraintes, mais la solution peut impliquer une interp6n6tration des bords. I1 est possible d'61iminer cette contradiction physique en introduisant des zones de contact aux pointes de la fissure. Le pr6sent article 6tudie l'effet du frottement dans les zones de contact pour des charges croissantes ~a partir de zero. Comme application, on consid~re une charge de cisaillement et le probl~me se r~duit ~i une 6quation int6grale singuli~re avec un noyau de type Cauchy. Cette 6quation est rfisolue num~riquement. Les rfsultats montrent que l'une des zones de contact est grande et que le frottement modifie l'ensemble du champ de contraintes, On a aussi obtenu les facteurs d'intensit6 de contraintes, l'ouverture de la fissure et la distribution du pression dans la plus grande zone de contact.