Pinning and Depinning of Crack Fronts in Heterogeneous Materials

摘要: The fatigue fracture surfaces of a metallic alloy and the stress corrosion silicate glass are investigated as function crack velocity. It is shown that in both cases there two self-affine regimes. At large enough length scales, universal roughness index {zeta}{approx_equal}0.78 recovered. smaller exponent close to {zeta}{sub c}{approx_equal}0.50. crossover {xi}{sub c} separating these regimes strongly depends on material, exhibits power-law decrease with measured velocity c}{proportional_to}v{sup -{phi}}, {phi}{approx_equal}1. exponents {nu} {beta} characterizing dependence v upon pulling force be {nu}{approx_equal}2 {beta}{approx_equal}2. {copyright} {ital 1997} American Physical Society}