Effect of Laser Shock Peening on Fatigue Stress Concentration of Polyester Reinforced by Al-Micro Powder Composites


Laser shock peening is a widely common process for materials treatmentand typically used for fatigue strength enhancement especially for metals.In this paper, its effect on polymeric composite materials studiedexperimentally. Unsaturated polyester was used as a matrix in order tocomposites preparation and Aluminum powder as fillers. A Hand lay-uptechnique has been used for composites making. Composites with threevolume fractions of Aluminum powder were prepared (2.5%, 5%, and7.5%). Fatigue specimens as a standard and with (1mm) semi-circularnotch are prepared for testing. The fatigue test was performed at roomtemperature and stress ratio (R=-1). Laser shock peening with two levelsof energy have been applied (1Joule, and 2Joule). The results showed anincrease in the endurance strength of the notch for 7.5% volume fractionespecially at 1J laser energy by about 26.7056% compared with the untreatment notched state, which in turn reduced the fatigue stressconcentration by about 21.0508% compared with standard fatigue stressconcentration. On the other hand, the presence of notch effect onendurance strength was increased after laser treatment of composites with2.5% volume fraction and the reduced was by about 39.698% at 2J laserenergy