Fatigue life prediction: A Continuum Damage Mechanics and Fracture Mechanics approach

Continuum Damage Mechanics (CDM) approach is used to predict crack initiation life and Fracture Mechanics approach predicts crack growth life. Strain controlled fatigue life of a ferrous alloy, EN 19 steel, has been determined using CDM and Fracture Mechanics approach. By combining these two approaches, life could be predicted with damage value in the material. All inputs required for the models have been determined by conducting monotonic, cyclic and fracture tests. Predicted life is also compared by conducting strain controlled fatigue tests. Predicted life in the strain amplitude range of 0.3–0.7% (fatigue life range of 102–105), compares well with the experimental results. All tests have been conducted at specimen level, stress ratio of −1 and at room temperature. The variation of crack initiation and crack propagation life with strain amplitude shows that maximum life is consumed by crack growth process at higher strain amplitude and at lower strain amplitudes, maximum life is spent for crack initiation process.

► Crack initiation life is predicted by CDM approach for strain controlled fatigue test.
► CDM and Fracture Mechanics approach helps to predict fatigue life with value of damage.
► Conducting multiple step test and using literature data fatigue life could be predicted.
► Result trend of crack initiation and propagation life are in line with literature.