Experimental investigation of the fatigue crack propagation in a closed-cell aluminum alloy foam

Fatigue crack propagation in a closed-cell aluminum alloy foam is experimentally investigated in this work. A series of fatigue tests are conducted to obtain the a-N curves (i.e. crack length vs loading cycle number) and da/dN-∆K curves (fatigue crack propagation rate vs stress intensity). Statistical analysis is carried out to assess the stochastic and scattering characteristics in the fatigue crack propagation of the foam, based on which a statistical fatigue crack propagation model is developed. Furthermore, the fracture surfaces of the foam specimens are characterized, as well as the fatigue fracture morphologies. It is demonstrated that the structural heterogeneity inherent in the material and the difference in the cell structures between different specimens account for the great scatter of the fatigue crack propagation in the close-cell aluminum alloy foam.