The Impact of 3 J Laser Pulse Energy to Enhance the Fatigue Lifespan of AA2024-T351 Induced via LSP

Abstract

Laser shock peening is a new method employed to increase the fatigue life of metals by inducing in-depth Compressive Residual Stress to about 1 mm. This helps prevent superficial failures, stress corrosion cracking and elongate the fatigue life and this has provided varying applications in the aviation industry. This study investigates the effect of pulse energy on fatigue lifespan of AA 2024-T351 and the results validated by the finite element method. When compared with the as-received specimen, the result confirms that LSP can significantly produce higher residual compressive stress, and elongate fatigue life of alloys marginally at the superficial layer while decreasing in-depth. The FE analysis of the laser peened specimen produced a good correlation with the experimental work. The fracture morphologies also show visible signs of fatigue striations in the micro-scale. The layout between each striation space is large for the as-received specimen, demonstrating a rapid fatigue growth rate whereas relatively small in the LSP-treated specimen indicating a stable fatigue growth.