A Numerical and Experimental Study of Induced Residual Stresses by Laser Shock Peening in An Aluminum Alloy

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: A Numerical and Experimental Study of Induced Residual Stresses by Laser Shock Peening in An Aluminum Alloy

ارائه دهنده: Provider: Ali Alipour

اساتید راهنما: Supervisors: Dr. Amirhossein Mahmoudi

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Gholamhossein Majzoubi-Dr. Rahman Seifi

زمان و تاریخ ارائه: Time and date of presentation: January 28, 2023. 4pm

مکان ارائه: Place of presentation: Seminar3

چکیده: Abstract: Laser shock peening is a relatively new method for creating compressive residual stresses. This method, as other methods of creating compressive residual stresses, improves the fatigue life of a component by increasing the component's resistance against stress corrosion cracking, crack propagation, fretting fatigue, cavitation, foreign object damage, and stress concentration. Compressive residual stresses and their depth under the effect of plastic deformation are much higher in laser shock peening than in shot peening and ultrasonic needle peening. In the process of laser shock peening, after the laser pulse strikes the component, if the pressure of the shock wave exceeds the Hugoniot elastic limit (HEL) of the material, the propagation of shock waves through the metal will lead to plastic deformation and, consequently, residual stresses. The magnitude and depth of residual compressive stresses in laser shock peening depend on various parameters such as the size and shape of the laser spot, laser intensity, wavelength, pulse duration, material properties, environment, etc. In this research, the laser shock peening process was investigated by two numerical study approaches using finite element (FE) software and experimental analysis. The overlapping effect, the number of laser strikes, the maximum pressure, the pulse diameter, and the pressure-time diagram are the parameters that were studied in this research. In the present thesis, the residual stresses were measured using the incremental hole-drilling method. According to the obtained results, with increasing the overlap, the number of laser strikes, and the maximum pressure, the depth of residual stresses also increased, however, the change in the pulse diameter had no effect on the field of residual stresses. Moreover, laser shock peening without coating had a much greater effect on the surface parameters than laser shock peening with coating. It should be noted that the results obtained from numerical simulations and experimental measurements were in a good agreement

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