ABSTRACT
A classical explanation of size effects, observed in brittle materials, is associated with concepts of fracture mechanics. Failure is explained by the full propagation of an existing defect or crack. Under a simple tensile stress state (Mode I of failure) of intensity σ, crack propagation occurs when the stress intensity factor:
becomes equal to the material toughness, Kc. In Equation (1) a is the initial length of the propagating crack and β is a dimensionless factor which embodies the geometry of the particle, the position of the crack, the direction and point of application of loads and the relative size of the crack in relation to the particle size. It is a function of the ratio a/D where D is taken as the average diameter of the particle. In the simulations performed, parameter β(a/D) was approximated by the expression given in Tada et al. (1985) and Oldecop & Alonso (2007) for a disk of a perfectly elastic-brittle material containing a central crack.
