  A representative volume element (RVE) based multi-scale method is proposed to
investigate the mechanism of fatigue crack propagation by the molecular
dynamics (MD) and the extended finite element methods(XFEM) in this study. An
atomic model of carbon steel plate is built to study the behavior of fatigue
crack at the micro scale by MD method. Then the RVE model for fatigue crack
propagation should be built by fitting the data which was obtained from the MD
result with the Paris law model. Moreover, the effect of micro-structural
defects including interstitial atoms, vacancies have also been considered in
this study. The results indicate that the micro-structural defects can deeply
influence the values of Paris law constants and the life of the specimen can be
evaluated by the proposed method.
