Five decades of crack path research

The complete solution of a crack propagation problem includes determination of the crack path. At the present state of the art the factors controlling the path taken by a propagating crack are not completely understood. In the last five decades there have been substantial advances in the understanding and prediction of both macroscopic and microscopic aspects of crack paths. This paper is a retrospective covering research on several crack path topics with which the author has been involved over the past five decades. All have a long history, but are still of interest and have practical engineering applications.