An inverse method to reconstruct crack-tip cohesive zone laws for fatigue by numerical field projection

Cohesive zone failure models are widely used to simulate fatigue crack propagation under cyclic loadings, but the functional form of such phenomenological does not have a strong micromechanical basis. While numerical techniques been developed extract crack-tip cohesive law for monotonic fracture from experimental strain information, elucidating unloading-reloading hysteresis representing accumulated and irreversible damage cycling is still challenging. Here, we introduce novel field projection method (FPM) reconstruct laws steady-state growth elastic information at various loading unloading stages within single cycle. The based on Maxwell-Betti’s reciprocal theorem, which considers material response be linear during unloading, albeit with reciprocity gap account inhomogeneous residual end each Through experiments, demonstrate that this FPM capable accurately extracting tractions separations, along elusive hysteresis, constitute growth. We discuss errors uncertainties associated inverse approach.