1. Important principles of fracture mechanics

1.1 Context

Fracture mechanics is a study that brings into play the usual parameters of mechanics, starting from an existing discontinuity: a crack or defect. In certain cases, depending on the dimensions of a crack and the loading condition, it is possible to predict the speed of crack propagation and the size at which the crack can lead to sudden rupture. This dimension, commonly referred to as the critical defect size, characterizes the harmfulness of the defect, i.e. the crack size above which the mechanical structure is no longer fit for use due to the loss of performance it causes.

Against this backdrop, it is legitimate to ask: why do accidents nevertheless occur (albeit rarely)? There are several possible answers. The first reason is, of course, that...