ABSTRACT
The structural size effect is probably the most important manifestation of fracture phenomena, at least from the engineering point of view. Therefore, it is important to relate the size effect behavior to the fracture properties of the material. This chapter describes the experimental determination of fracture properties based on size effect, which includes a discussion of the basic regression relations. It also describes the experimental and calculation procedures recommended by the existing RILEM Recommendation, and some improvements in the regression relations incorporating weighted least-square fitting. Experience shows that different experimental techniques or different analysis may lead to different values of theoretically identical fracture parameters: fracture toughness, fracture energy, and size of the fracture process zone. The method works equally well for a number of geometries, but three-point-bend beams are recommended for the purpose of standardization. The loads and reactions are applied through one hinge and two rollers with a minimum possible rolling friction.
