Neutron and X-ray diffraction studies and cohesive interface model of fatigue crack deformation behavior

Abstract

The crack-tip deformation behavior during a fatigue test with a single overload is studied using (1) neutron diffraction technique, from which both elastic lattice strain and dislocation densities are obtained, and (2) the finite element method that is based on an irreversible and hysteretic cohesive interface model. Neutron strain measurements and finite element simulations show a good qualitative agreement. The large plastic zone induced by the overload and the resulting compressive residual strains, are observed in front of the crack tip after the overload, are the principal reasons for the fatigue crack growth retardation.