A Fatigue Damage Propagation Model Based on Locally Periodic Micro-crack Growth

This paper develops a new micro-mechanical damage model for fatigue crack propagation in tensile (Mode I) cyclic loading. The double-scale fatigue damage model is entirely obtained through small-scale yielding descriptions of micro-crack propagation. Based on the Paris fatigue crack growth law, the stress intensity factor range is expressed thanks to an appropriate micro-mechanical energy release rate analysis coupled with asymptotic homogenization developments. The macroscopic fatigue crack evolution law is established. Numerical simulations are presented. The reliability of the model to reproduce stress-strain shielding is demonstrated. The influence of the microstructural length on fatigue damage evolution is illustrated. The numerical results are compared with fatigue crack propagation tests performed on Ti-6Al-4V titanium fashioned by additive layer manufacturing (ALM). Through the calibration process, the model agrees with the experimental results.