Comparison of the Simulation and Experimental Fatigue Endurance Behaviors in T6-Treated Nanosized SiC Reinforced Al Alloy Composite

Abstract

The fatigue endurance behaviors of SiC nanoparticle reinforced 6061 Al alloy composites (T6-treated SiCnp/6061Al) were simulated by finite element (FE) method with the help of recently developed cyclic viscoplastic constitutive model and its implementation into a FE code Solidworks simulation. The Rice-Tracey damage parameter was used for the crack path calculation did the prediction agree completely with the observed behavior. FE simulation of the materials showed that the composite samples exhibit regular crack propagation behavior. At early stages of loading the hydrostatic stress was low and the damage evolution was affected by the plastic flow. The damage grew in outer layers where the maximum equivalent plastic strain occurs. By increasing the number of fatigue failure cycles at 3×105cycles, the hydrostatic stress increased and its effect became dominant. In the 200 MPa tests the slope of the tensile portion of the hysteresis loops decreased with fatigue cycling, indicating progressive decrease in the tensile modulus. Stress concentration, due to the presence of nanoparticle reinforcements, produces controlled crack growth and higher stresses, which are related to regular energy release by the material during fracture. The need for higher stresses for a crack to propagate reveals the materials microstructural strength.