Fatigue life improvement of Aluminum alloy by using laser and ultrasonic techniques

Abstract

Laser Peening (LP) and Ultrasonic Peening (UP) treatments with fatigue interaction were studied for 2017A-T3 Aluminum alloy under room temperature (RT) and stress ratio R = -1. Experimental mechanical properties and fatigue behavior of the above alloy were obtained for different conditions of LP & UP surface treatments. The mechanical properties ultimate strength (σu) and yield stress (σy) were enhanced by 8.7% and 20.4% respectively, while the above parameters were improved by 10.3% and 30.7% for ultrasonic peening (UP). Constants fatigue behavior for the mentioned treatments have been also determined. The fatigue endurance limit was increased by 38% for LP and 61% for UP. The fatigue life for both treatments was significantly improved compared to as-received metal. Cumulative fatigue damage testing were carried out for two steps loading and it is observed that the fatigue life for LP and UP treated specimens were improved compared to the unpeened results. Two proposed cumulative non-linear models were presented one for LP and other for UP. These models showed that safe and satisfactory predications of fatigue life but the ultrasonic model gave 1.8 factor of safety while the laser model showed 1.2 factor of safety.