The exact shape of a deformed internal slant crack under biaxial loading

Abstract

A theoretical investigation has been performed to determine the exact geometrical features of an inclined, biaxially loaded, crack in an infinite elastic plate. It has been shown that the shape of the deformed Griffith crack, as this follows from the exact linear elastic displacement field at the lips of the crack, is always an ellipse in opposition to the singular and two-term solutions which give a parabolic shape for the deformed lips of the crack. The combined effect of the mode of loading, the load biaxiality and the crack orientation on the lengths of the semiaxes of the ellipse, and the orientation of its major axis with respect to the initial crack was studied in detail. It is also shown that in general the positions of the initial crack tips after deformation on the curve of the ellipse do not coincide with the points of the maximum curvature of the ellipse. The case, where the ellipse presents overlapping lips and where the elastic solution becomes invalid, has been examined and the configurations of the problem-parameters for which this phenomenon happens has been established. These important features of the deformed shape of the loaded crack may have a considerable influence on the mode of loading and the behaviour in yielding and fracture of the cracked bodies.