Calibration of phase-field brittle fatigue model by purposeful design of crack driving forces

Abstract

A new general multiparameter phase-field approach for high-cycle fatigue fracture is proposed. Fatigue is modelled by adding a new energy dissipation term accounting for fatigue phenomena, which results in two additional crack driving forces. The current model analysed in the paper possesses four fatigue parameters, whereby each of the driving forces depends on two parameters. The crack driving forces are designed so as to enable a more accurate reproduction of S-N curves and the Paris’ law by a single set of identified parameters, which is not possible by simpler phase-field models relying on only one or two fatigue parameters. The results indicate that the presented model is able to capture various macroscopic phenomena, including the mean stress effect, the evolution of complex crack patterns under cyclic loading and the reproduction of experimental S-N and Paris curves of realistic materials. Extensive parametric analyses have revealed that there exists a strong correlation between the model fatigue parameters and the parameters defining S-N and Paris’ curves, which opens the possibility of straightforward calibration of each parameter from experimental data.