Impact of Mass Flow Rate on Shot Peening Effect Based on Coupled DEM-FEM Model
In the previous finite element shot peening model,only the stress and strain occurred in the target material after shot peening can be studied,and in the previous discrete element shot peening model,only the collision interference between the shots can be studied.The two types of shot peening models have their own advantages and disadvantages,but it is not possible to study the interactions between the shot-pellet and shot-target materials in the peening process at the same time.However,the shot-pellet and shot-target interactions during the peening process cannot be investigated simultaneously,and the shot velocities are artificially given in the previous studies,which is obviously not in line with the reality.Therefore,based on the above reasons,the work aims to propose a new method of coupling finite elements(FEM)with discrete elements(DEM),i.e.,the DEM-FEM coupling function has been realized within the ABAQUS software by defining the key words,and this method has been applied to establish the shot peening model.In this method,the shot is regarded as an equal-diameter rigid body,and the shot-pellet and shot-target interactions as well as the entire shot flow are effectively simulated by rigid-body dynamics,and it is verified that the established model can accurately reflect the actual shot peening process.In this work,the shot velocity is calculated by Fluent fluid software.Mass flow rate has an important impact on the shot peening effect.In the case of a certain shot peening pressure,the mass flow rate is different while the intensity of the collision interference between the shots is different,the shot peening velocity is different and the effective energy transferred from the shot to the target material is different,which ultimately leads to different shot peening effect.In the established DEM-FEM coupled shot peening model,the magnitude curve mass flow rate and the magnitude curve velocity were introduced to control the shot generation rate,the parameters of the two magnitude curves were adjusted,and the effects of the mass flow rate(2 kg/min,4 kg/min and 6 kg/min)on the maximum residual stress,surface residual stress and surface roughness were investigated.The numerical simulation results showed that the mass flow rate had a significant impact on the peening effect,the maximum residual stress decreased with the increase of mass flow rate,from-596.77 MPa at 2 kg/min to-581.91 MPa at 6 kg/min,the surface residual stress increased and then decreased with the increase of mass flow rate,from-420.86 MPa at 2 kg/min to-420.86 MPa at 4 kg/min and the surface residual stress decreased with the increase of mass flow rate,from-420.86 MPa at 2 kg/min to 472.06 MPa at 4 kg/min,and then decreased to-450.50 MPa at 6 kg/min and the surface roughness decreased with the increase of mass flow rate from Ra=11.21 μm at 2 kg/min to Ra=9.82 μm at 6 kg/min.The shot peening experiment is designed,and the mass flow rate of 2 kg/min is selected.The surface residual stress and surface roughness of the simulation results are compared with the experimental results,and the errors are found to be within the allowable range,which proves the accuracy of the numerical simulation.
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