TCD-based criteria for quasi-brittle fracture of materials and structures

Abstract

Nonlocal fracture criteria, recently developed within the framework of the theory of critical distances, are analyzed. It is marked that the scope of application is limited to cases of brittle or quasi-brittle fracture with a small fracture process zone. To expand the scope of the criteria for cases of fracture with a developed fracture process zone, it is proposed to abandon the hypothesis of the size of this zone as a material constant, associated only with the microstructure of the material. New nonlocal criteria for quasi-brittle fracture are proposed, which are the development of the average stress criterion, and point stress criterion, and which contain a complex parameter that characterizes the size of the fracture process zone and accounts not only for the material microstructure, but also plastic properties of the material, geometry of the specimen, and its loading conditions. Formulae for critical stress in the problems of the fracture of plates with a circular hole in uniaxial tension and compression are obtained. Calculation results are in good agreement with experimental data.