Estimating the elastic interaction factors of two coplanar surface cracks under mode I load

Two cracks sufficiently close together will interact by causing the stress intensity factor at the tips of each to increase. The amount of this increase can be quantified through the use of interaction factors. This paper studies the form of these for the important and practical special case where the cracks have a semi-elliptical shape. A continuous method of approximate solution is proposed in this paper, and it is shown to be effective in the closeness of its predictions to those in the literature, and to our own finite element analyses. The work is a precursor to an assessment when cracks are close enough for interaction to need evaluation. This forms the subject of a companion paper.