Parameter Determination Of Constitutive Model Of 18CrNiMo7-6 And Theoretical Analysis And Simulation Of Ultrasonic Rolling

Ultrasonic rolling machining is a very effective surface finishing technology,which can improve the surface integrity of materials,introduce residual compressive stress into the surface of materials,and improve the fatigue resistance of materials.In this paper,the constitutive model parameters of 18 CrNiMo7-6 material were determined by experimental method,and the finite element simulation model of ultrasonic rolling on the surface of shaft parts was established.An analytical model of surface roughness and residual stress was established based on elastic-plastic mechanics and Hertz contact theory for surface ultrasonic rolling of planar workpiece.Finally,the validity of the model was verified by experimental method.The specific research work of this paper consists of the following aspects:1.The constitutive model parameters of 18 CrNiMo7-6 material were determined by using quasi-static tensile test and split Hopkinson pressure bar test.The parameters of temperature in the machining area,strain hardening effect and strain rate strengthening effect were measured by using infrared temperature measuring device,MTS axial tension-compression fatigue machine and split Hopkinson pressure bar test system.According to the experimental results,the constitutive model parameters of18 CrNiMo7-6 material were determined.2.According to the mechanical characteristics and stress-strain analysis of workpiece materials in plane ultrasonic rolling process,an analytical model of surface roughness and residual stress was established based on elastoplastic mechanics and Hertz contact theory.3.Aiming at the surface ultrasonic rolling machining of shaft workpiece,the finite element simulation model of ultrasonic rolling machining of shaft workpiece surface was established based on the constitutive model parameters of 18 CrNiMo7-6 material,and the simulation study of ultrasonic rolling machining under different process parameters was carried out by the model.4.Using the ultrasonic rolling device,the ultrasonic rolling plane machining test with different static pressure and feed speed was carried out.The results show that the analytical model of surface residual stress and the mathematical model of surface roughness established in this paper are in good agreement with the experimental results,which provides a new method for the theoretical analysis of surface roughness and residual stress of ultrasonic rolling workpiece.5.Ultrasonic rolling processing device was used to carry out ultrasonic rolling processing test on the surface of shaft parts,and the residual stress and surface roughness of the processed samples were measured.The experimental results show that the simulation results obtained by the finite element model are in good agreement with the experimental results,which provides technical support for the study of surface roughness and residual stress of shaft parts by using the simulation analysis method.In summary,theoretical analysis and experimental study were used to study the surface residual stress and roughness of ultrasonic rolling materials on the surface of planar workpieces.Based on the material constitutive model parameters,the surface residual stress and roughness of shaft workpieces were studied by using finite element simulation analysis and experimental study.The results show that the theoretical analysis model and the finite element simulation model established in this paper can be used in ultrasonic rolling machining,which are practical and effective in engineering.