基于DEM-FEM耦合模型的质量流量对喷丸强化效果的影响

Impact of Mass Flow Rate on Shot Peening Effect Based on Coupled DEM-FEM Model

目的提出一种将有限元(FEM)与离散元(DEM)相耦合的新方法,即通过定义关键字的方式在ABAQUS软件内实现DEM-FEM耦合功能,并应用此方法建立喷丸强化模型。方法将弹丸视为等直径刚体,利用刚体动力学模拟弹丸-弹丸和弹丸-靶材之间相互作用以及整个弹丸流。通过建立的DEM-FEM耦合喷丸强化模型研究质量流量对残余应力场和表面粗糙度的影响。结果质量流量对喷丸强化效果有显著影响,最大残余应力随质量流量的增加而减小,由2 kg/min时的–596.77 MPa下降到6 kg/min时的–581.91 MPa;表面残余应力随质量流量的增加先增大后减小,由2 kg/min时的–420.86 MPa增大到4 kg/min时的472.06 MPa,随后减小到6 kg/min时的–450.50 MPa;表面粗糙度Ra随质量流量的增加减小,由2 kg/min时的11.21μm减小到6 kg/min时的9.82μm。设计了喷丸强化实验,对质量流量2 kg/min的结果进行了验证。结论实测值与模拟值吻合较好,所建立的模型可以准确反映实际喷丸强化过程。质量流量对喷丸强化效果具有显著影响。

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=11.21mm at 2 kg/min to Ra=9.82mm 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.