Fundamentals of brittle fracture

The basic findings explaining brittle fracture processes will be reviewed - starting with the necessity resulting from the difference in ultimate and technical strength to introduce flaw or crack concepts. The stress-strain field surrounding such flaws or cracks will be discussed. For the assessment of fracture initiation and propagation criteria will be provided, i.e. a short introduction into fracture mechanics will be given. The criterion of maximum principal stress is considered as the guiding criterion when brittle behaviour prevails. Characteristics features of the fracture appearance as a consequence of kinematics of the fracture process itself or a superposition of different fracture modes will be analyzed. These considerations will be illustrated by examples showing the behaviour of glass samples since glass turned out to be an ideal model material for brittle fracture. Nevertheless, throughout the lecture general features of brittle fracture are discussed.