Simulation Of Machining Residual Stress And Optimization Of Cutting Parameters For Thin-Walled Frame Parts

As an important component of the aircraft structure,the thin-walled integral frame part can effectively reduce the weight of the aircraft and improve the maneuverability of the aircraft and spacecraft.Since the thin-walled integral frame part is characteristic of large size,complex structure,low rigidity and high surface precision,it is generally machined by CNC.However,under the coupling influence of residual stress,cutting force,clamping force and other factors,the workpieces may be subject to bending,torsion and other deformation after machined,and then the accuracy of processing can hardly be effectively guaranteed.For this reason,this thesis takes the thin-walled frame part of aluminum alloy 7075 T651 as the research object,and relies on the orthogonal test,numerical simulation and genetic algorithm methods to study the effects of the initial residual stress and machining residual stress on machining deformation of the thin-walled frame part of aluminum alloy 7075 T651.The main works in this thesis can be concluded as followings:1)The influence of initial residual stress on machining deformation of thinwalled frame parts is analyzed.The generation and testing technology of initial residual stress are described and summarized.Based on finite element analysis software ABAQUS,fortran subroutine is used to exert the initial stress field,and the “birth and death element” technology is adopted to remove the material and conduct the finite element simulation.Therefore,the effects of initial residual stress release and redistribution on the workpiece deformation are concluded.2)The influence of cutting parameters on machining residual stress is analyzed.ABAQUS software is utilized to establish the two-dimensional cutting simulation model.Based on the orthogonal test method,finite element simulation is carried out so that the empirical formula of machining residual stress which is related to cutting parameters can be established.And Combined with the variance analysis,the influence of cutting parameters on the residual stress and the primary and secondary relation of the cutting parameters to the residual stress are accordingly concluded.3)The influence of the initial and machining residual stress on the deformation of workpieces is comprehensively analyzed.Firstly,the thin-walled frame part was simplified.The machining residual stress values obtained from the step 2)is applied to the surface of the finite element model,and then the influence of the residual stress generated by cutting parameters on the machining deformation is obtained by means of the finite element analysis software ABAQUS calculation.Combined with the distribution feature of the initial residual stress in step 1),the finite element simulation helps to conclude the coupling influence of the initial residual stress and machining residual stress on overall deformation trend of the workpieces.4)The cutting parameters based on machining residual stress are optimized.Taking the cutting parameters as design variables,the thesis aims at the smaller machining residual stress and the maximum material removal rate,establishes the multi-objective optimization function of cutting parameters combined with the constraint range of various cutting parameters,and optimizes cutting parameters during machining by means of the genetic algorithm method.In summary,this thesis provides a theoretical basis for revealing the influence of residual stress on the machining deformation of the thin-walled frame part,and lays the foundation for the design of the processing technology of thin-walled frame parts.