A Fatigue Crack Growth Life Prediction Model for Discontinuous Reinforced Metal-Matrix Composite: Influence of Microstructure

摘要

Under the fully strain-controlled conditions, a closed-form multistage fatigue crack growth (MSFCG) life prediction model has been developed for discontinuous reinforced MMCs (DRMMCs) considering the effect of microstructural features. The model considers crack nucleation, small crack, and long crack life. The crack initiation is evaluated on the bases of slip steps deepening into a fatigue crack under the cyclic strain. Next, the small crack growth life is investigated within the microstructural threshold. Finally, for long fatigue crack propagation, previously developed model by Tevatia and Srivastava is modified and incorporated in the current model. Under the total strain-controlled conditions, reinforcement in the matrix results in an increase in both (i) the level of cyclic plastic deformation and (ii) cyclic plastic zone size near the vicinity of crack tip. The effect of initiation and small crack growth life is significant for low cycle fatigue applications.