Dynamic tests with different load ratios and frequencies provide designers with the necessary information to evaluate the longevity of different structures as well as minimize weight due to a possibly smaller factor of safety. The influence of loading frequency on the fatigue behaviour of an aluminium composite material (ACP) with an aramid honeycomb core was studied. The mechanical behaviour was assessed by three-point static bending tests, followed by cyclic flexural fatigue tests employing the fabricated sandwich samples, with loading frequencies of 5, 7.5 and 10 Hz. The experimental results were presented on a single graph in order to highlight the different behaviours for the adopted frequencies. Indeed, the tests allowed the authors to determine the different cycle number values necessary to achieve resistance losses of 10 and 25%, respectively. The experiments were carried out for the same loading level of 80% of the maximum force, which is taken as equal to the elastic limit in order to avoid the field of plastic deformations.
This study focused on the fatigue and corrosion fatigue of maraging steel 18Ni (250). The 18Ni (250) samples were tested for axial fatigue in air and 3.5% NaCl solution. The effects of loading frequency and stress ratio on the fatigue strength of 18Ni (250) were studied. in air, the loading frequency was 10 Hz, and the stress ratio was 0.5. however, three loading methods were used in the 3.5% NaCl solution: (i) the loading frequency of 1 Hz and stress ratio of 0.5; (ii) the loading frequency of 1 Hz and stress ratio 0.1, and (iii) the loading frequency 5 Hz and stress ratio 0.5. The corrosion fatigue strength of samples in the 3.5% NaCl solution was 63.3% lower than that of the samples in air. The fractures in the samples were observed after the test.
This study focused on the fatigue and corrosion fatigue of maraging steel 18Ni (250). The 18Ni (250) samples were tested for axial fatigue in air and 3.5% NaCl solution. The effects of loading frequency and stress ratio on the fatigue strength of 18Ni (250) were studied. In air, the loading frequency was 10 Hz, and the stress ratio was 0.5. However, three loading methods were used in the 3.5% NaCl solution: (i) the loading frequency of 1 Hz and stress ratio of 0.5; (ii) the loading frequency of 1 Hz and stress ratio 0.1, and (iii) the loading frequency 5 Hz and stress ratio 0.5. The corrosion fatigue strength of samples in the 3.5% NaCl solution was 63.3% lower than that of the samples in air. The fractures in the samples were observed after the test.
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