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A fatigue crack growth life prediction model for metal matrix nanocomposites: contribution of strengthening factors

The nanocomposite materials acquired more attention in industries due to high strength, stiffness, and fatigue life. Fatigue behaviour is an important aspect in metal matrix nanocomposites (MMNCs) and needs to be investigated. In the proposed model, the low cycle fatigue (LCF) behaviour of MMNCs is considered as a localized damage development (i.e. fatigue crack growth) phenomenon under cyclic loading. The actual degradation takes place within the fatigue damage zone (FDZ) that lies very near to the crack-tip and dominates the whole LCF behaviour. The strengthening factors considered in the present study include: Orowan strengthening effect, dislocation density of matrix, load-bearing reinforcement effect, the porosity and microstructural properties of the MMNCs. For validation, the proposed model has been explored to fit on several reported experimental data sets and it is found to offer good prediction and statistically in agreement with the data. Further, to observe the impact of various model parameters, sensitivity analysis has also been performed and reported that a small change in cyclic strength coefficient resulted the maximum deviation and the change in porosity the least. The presented investigations in this work, represents detailed model development and sensitivity analysis of fatigue crack growth life of MMNCs.