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Go to Editorial ManagerIn this work, constant and increasing temperature fatigue interaction effect on fatigue behavior of 2017-T4 aluminum alloy was investigated. Fatigue tests at constant load constant temperature and constant load increasing temperature were performed for five applied stresses which are (350,275,200,175 and 150 MPa) that based on the tensile test behavior .The constant temperatures were room temperature (RT) (25 ?C) and 100 ?C. While the increasing temperatures were RT, 50 ?C, 100 ?C and 150 ?C for one test program. The constant fatigue property of the increasing temperatures was observed the worst case compared to the others constant fatigue properties. A new variable temperature fatigue damage model was proposed. It is based on the S-N curve and taking into account the effects of constant loads and variable temperature. A comparison between prediction of the proposed model and crack growth rate due to Miner rule was made. The results proved that this model is satisfactory and gave safe results than Miner rule compared to experimental data.
Improving fatigue life is one of the most important issues in mechanical design; an investigation has been conducted on Al 2017-T4. Group of samples have been machined and prepared, some of specimens have been treated using the ultrasonic impact treatment (UIT) with one line peening. The fatigue tests were carried out under constant and variable amplitude (R=-1) at ambient temperature, in order to find out the fatigue life S-N curve and strength after treatment. It has been found significant increasing in strength after it was treated by (UIT). The fatigue strength is improved after treatment up to 4.16% at 107 cycles, enhancement are present with 24% and 18.78% for the cumulative fatigue lives low-high and high–low respectively. These results also show a strong tendency of increasing of fatigue strength after application of (UIT) with increase in mechanical properties of material used.