Studies on Impact Fatigue : Part III, Impact Fatigue Investigation on 99.5% Pure Aluminum and Duralumin

In the 1st and 2nd reports on the studies on impact fatigue, the authors had reported on the impact fatigue characteristics of the carbon steels that an impact fatigue failure occurred in the cycle range exceeding the critical number of stress cycles observe in the ordinary fatigue test and in the stress range below the ordinary fatigue limit, and that the impact fatigue failure occurred at a lower value of the inelastic strain amplitude than that observed at the stress level of the ordinary fatigue limit, and moreover, less cumulative hysteresis energy was needed for the impact fatigue failure than for the ordinary fatigue failure. In the study reported here, the investigations were made using pure aluminum and duralumin, and the following results were obtained : the impact fatigue characteristics are the same as those mentioned above in the case of pure aluminum, but, a little different strength behavior and a peculiar inelastic behavior were observed in the case of duralumin ; and the latter was discussed with the aid of a mechanical model.