The stress intensity factors near an angular point on the front of an interface crack

Abstract

In a previous paper published in the same journal, we investigated the asymptotic behaviour of the stress intensity factors in the vicinity of an angular point on a crack front in a homogeneous, isotropic elastic body. This required, as a prerequisite, to study the three-dimensional stress singularity prevailing at the angular point. It was concluded that in the only case considered there where the crack occupied the major part of the crack plane, all stress intensity factors went to infinity as the distance to the angular point went to zero. Here we investigate the same problem but for an interface crack, that is, one lying between two isotropic media with different elastic constants. Again, it is necessary to first study the three-dimensional stress singularity at the angular point. Two cases arise: one where all three modes are real (that is, the exponents they involve are all real), and one where one mode is real and the other two complex (that is, the exponent they involve is complex). We consider only the second case here. The asymptotic study of the stress intensity factors along the crack front near the angular point reveals that they all diverge to infinity, some (but not all) of them presenting oscillations of indefinitely growing amplitude. With regard to the energy release rate, it generally goes to infinity without any oscillations, but it does oscillate in a certain particular case. Consequences upon crack propagation near the angular point are finally envisaged.