Fatigue tests and a damage mechanics-based fatigue model on a cast Al-Si-Mg aluminum alloy with scratches

Scratches can significantly influence the fatigue performance of materials or structures even with several hun-dred microns depth. In this study, the effect of scratch defects on the fatigue performance of ZL114A cast aluminum alloy is systematically studied. Fatigue tests of scratched smooth specimens and scratched hole plates are conducted. For scratches with the depths of 0.15, 0.25 and 0.35 mm, the mean fatigue life is reduced by about 35 %, 50 % and 61 % compared to unscratched specimens. A novel fatigue damage model based on continuum damage mechanics (CDM) is then developed. This model can well evaluate the fatigue performance of actual components with scratches and is convenient to use by avoiding modeling the real tiny scratch. The comparison between the predicted results and experimental data shows a good accuracy.