3. Failure mechanisms by type of fracture

No matter how carefully a material is crafted, it will always contain cracks or internal defects invisible to visual inspection. Under the effect of mechanical, thermal or chemical stress, cracks can develop slowly or abruptly, leading to fracture. These complex phenomena are the subject of fracture mechanics, whose aim is to characterize the cracking behavior of structures as a function of stress, crack size and resistance to cracking. In practice, given the many parameters contributing to failure mechanisms, theoretical studies are accompanied by physical tests carried out on specimens to validate understanding of the phenomena. Failure can occur instantaneously or progressively, and is conditioned by material properties and stress modes, as shown in figure 6 . This discipline is the subject of...