The energetic size effect may be intuitively explained by considering the panel in Fig. 1c,d, initially under a uniform stress equal to σ σ N . Introduction of a crack of length a , with a damage zone of width h at the tip, relieves the stress, and thus also the strain energy, from the shaded undamaged triangles of slope k on the flanks of the crack. Then, if k and a / D are approximately the same for different sizes, the energy released from the shaded triangles is proportional to U ¯ ¯ D 2 , while the energy dissipated by the fracture process is proportional to G f D ; here G f = fracture energy of the material, U ¯ ¯ = σ σ N 2 / 2 E = energy density before fracture, and E = Young's elastic modulus. The discrepancy between D and D 2 shows that a balance of energy release and dissipation rate can exist for every size D only if σ σ N decreases with increasing D . If the energy dissipated within the damage zone of width h is added, one obtains the Bažant (1984) size effect law (Type 2):