Defects induced multiscale kinetics of damage-failure transition under very high cycle fatigue

摘要

Multiscale mechanisms of fatigue damage-failure transitions in metals are studied for High Cycle and Very High Cycle Fatigue and analyzed as duality of inherently linked two types of singularities related to the singularity of multiscale damage kinetics under crack nucleation and singularity of stress field at the crack tip as the classical framework of fracture mechanics. The singularity of multiscale damage kinetics was established as natural precursor of crack nucleation and specific nonlinearity (metastability) of free energy release in term of damage parameter (defect induced strain). Experimentally estimated scales and power exponents were used in the constitutive laws of crack advance as the structure sensitive parameters for characteristic damage-failure transition stages.