Lecture
This lecture covers the concept of crack growth in materials, where a crack can be seen as the limiting case of an oblate spheroid or a prolate ellipsoid. It discusses how crack growth occurs by extending the crack infinitesimally, considering the total free energy of the material. The stress intensity factor and strain energy release rate are explained, along with the critical stress intensity factor for crack growth onset. The lecture also delves into the relationship between crack growth conditions, energy considerations, and the material's fracture toughness. Various models and concepts related to fracture mechanics, stress fields near crack tips, and dissipative processes are explored.