Doctoral thesis: On the Role of Process Regions at Stationary and Growing Cracks

Sammanfattning: Studies of crack behaviour and fracture are generally performed using continuum analysis. Thus, the process region is either not considered at all or assumed to be point-sized. In the latter case it is often ascribed a desired property, usually the ability to consume energy.A major step towards the understanding of the fracture process region the concept of autonomy of the near tip field was introduced by Barenblatt in 1962. He also introduced a cohesive modulus as a description of the material behaviour in the crack tip vicinity. This implies again that process region should be small in some sense. In an elastic surrounding smallness of the process region must be related to a significant geometrical length, usually the crack length. Which introduces the question about what happens in the case the crack is of similar size or even small compared with the linear extent of the fracture process region. The present thesis brings some light into this.