Numerical Simulation Of Residual Stress Field And Surface Roughness Of Microparticle Shot Peening

Microparticle shot peening is a kind of surface strengthening technology which is different from traditional shot peening.By using smaller diameter particles to impact the target at a faster speed,the surface roughness of the shoted parts is reduced while the residual compressive stress is introduced,and the hardness,fatigue strength and wear resistance of the metal parts are improved.The residual compressive stress field and the surface roughness are the mechanical reflections of the interaction between the microparticles and the target,and are influenced by the mechanical properties of the material and the shot peening parameters.The arc height test method,which is usually used to measure the strength of shot peening,does not reflect the reaction of the target to the jet,and the influencing factor of the diameter of the peening dents is exactly the same as the residual stress field and the surface roughness.In this paper,ANSYS / LS-DYNA finite element software was used to simulate the process of the microparticle shot peening of TC4 titanium alloy.The relationships between the parameters of the microparticle shot peening technology and the residual compressive stress field、the surface roughness were studied.The relational expressions between the diameter of peening dents,the depth of residual pressure stress field,the surface roughness and particle diameter,impact velocity,particle and target material properties were deduced by used the dimensional analysis method.Firstly,a finite element model of single shot was established.The diameters of microparticles were 40,60,80,100 and 120μm;The impact velocities were 150,160,170,180,190 and 200m/s;The friction coefficients were 0.15,0.25,0.35 and 0.45;The impact times were 1,2,3,4 and 5 times;The impact angles were 30 °,45 °,60 °,75 ° and 90 °;The overlapping ratioes were 0,1/4,2/4,3/4 and 1.The results showed that microparticle diameter,impact velocity and impact angle had a great influence on the residual compressive stress and surface roughness,while friction coefficient and overlapping ratio mainly affected the residual compressive stress,and the impact times mainly affected the surface roughness.Secondly,15 combinations of results data were made up of five microparticle diameters of 40,60,80,100,120 μm and three impact velocities of 150,170,190 m / s showed that the relationships between the depth of residual compressive stress layer,surface roughness and the peening dents diameter were all linear.The three were all linearly related to the product of the diameter and velocity of the microparticle.The relational expressions between them were obtained by using dimensional analysis method.By comparing the simulation results of other shot peening parameters,the maximum error was less than 4%.