Numerical Simulation Analysis Of Laser Surface Strengthening

Laser Shocking Peening(LSP)is a kind of surface modification technology that uses high power density with short pulse laser to improve the mechanical properties of metals.LSP techniques mostly use the circular spot of Gaussian distribution with spot energy,and the center of the spot has the maximum shock wave pressure.Compared with the traditional mechanical shot peening and rolling strengthening,LSP technology has many advantages,such as high processing flexibility,high efficiency,deep residual compressive stress layer and good surface quality,which has potentially important applications in the manufacturing fields of aviation and aerospace.2024-T3 aluminum alloy is a high-strength structural aluminum alloy used for manufacturing aircraft skeleton parts.It is great significant to study LSP law of 2024-T3 aluminum alloy for improving its fatigue life and other mechanical properties.In this paper,the 2024-T3 aluminum alloy is taken as the research object and the finite element software ABAQUS is used to simulate the residual stress field of 2024-T3 aluminum alloy.The effect of laser parameters on the residual stress field is systematically investigated by using the Johnson-Cook(JC)constitutive model.The main contents and conclusions are as follows:To analyze the residual stress distribution on the surface and depth direction of a single spot by analyzing the laser parameters(power density,spot size,pulse width and impact times).Appling the appropriate power density can improve the surface residual compressive stress of the target.The larger the spot radius is,the more uniform the residual compressive stress distribution is.The pulse width makes the increase of residual compressive stress layer more stable.The certain impact times makes the surface residual compressive stress and residual compressive stress layer depth maximum.To analyze the influence of the center distance and overlap rate on the residual stress field under multiple spots.Through the discussion of the center distance,it is concluded that the influence of square arrangement and regular hexagonal arrangement on the residual stress field are the same,which will make the surface residual compressive stress distribution uneven and have certain residual compressive stress layer,and the loading conditions are not the same,different residual tensile stresses will be generated on the bottom of the model.The greater the overlap rate is,the more uniform the surface residual compressive stress distribution is,and its value will increase,the residual compressive stress layer has also a certain increase,but there is still a lot of residual tensile stress on the bottom surface of the model.For this phenomenon,the double-sided impact is used to eliminate the residual tensile stress.