| Blade is the core part of aero engine.The residual stress on its surface has great influence on its fatigue life in service environment.In order to meet the performance requirements of blades,titanium alloy is widely used in the manufacture of aeroengine titanium alloy blades.The surface residual stress has great influence on the fatigue life,yield limit and strength limit of titanium alloy blade.Because belt grinding has the characteristics of cold grinding and flexible grinding,it is often used in industry to conduct the final surface treatment of titanium alloy components such as air-generated blades in order to control the residual stress on the workpiece surface.Therefore,it is of great significance to master the formation law of residual stress on grinding surface of belt,to control and eliminate residual stress and to guide the machining of titanium alloy workpiece.At present,scholars at home and abroad have done some research on the characterization of residual stress of abrasive belt grinding surface.To solve these problems,this paper studied the characterization methods to the surface residual stress of aeroengine titanium alloys blade after abrasive belt grinding with the simulation modeling and experiment,revealed the distribution law of residual stress on grinding surface of titanium alloy,And established the mathematical model of grinding parameters and the residual stress with different methods,realized the characterization of the residual stress.The main research contents are as follows:(1)Research on residual stress characteristics of titanium alloy surface after belt grinding.Firstly,finite element simulation analysis was carried out by ABAQUS for grinding process of multi-abrasive belt of sheet titanium alloy piece,and the distribution characteristics of residual stress after grinding of titanium alloy pieces under multiabrasive condition were studied.Then,based on the orthogonal experiment method,the grinding experiment of thin wall parts of titanium alloy was designed,and the grinding experiment platform of sheet pieces of titanium alloy was built.Finally,the experiment of titanium alloy sheet belt grinding was carried out on the experimental platform and the distribution of residual stress after grinding was detected.(2)The residual stress characterization of titanium alloy belt grinding surface based on elastic-collision mechanics.Firstly,based on elastic mechanics and collision mechanics,the mechanical model of residual stress on titanium alloy surface after belt grinding was established.Secondly,the coupling relation between process parameters and model parameters of belt grinding is studied,and the mutual mapping between macro and micro is realized.Then,based on the analysis and calculation of the structural characteristics of the model,the mathematical model of grinding process parameters and surface residual stress of titanium alloy belt was established,and the surface residual stress of titanium alloy belt grinding was characterized.Finally,the simulation results are compared with the corresponding experimental results to explore the characteristics and sources of errors.(3)The residual stress characterization of titanium alloy belt grinding surface based on molecular dynamics.Firstly,the model of surface molecular grinding system of titanium alloy was established on the basis of molecular dynamics,and the intermolecular potential was analyzed and the corresponding potential function was selected.Secondly,according to the characteristics of the molecular system and the selected molecular potential function,the potential energy model of the molecular system is established and the corresponding initial conditions are set.Finally,the simulation results are compared with the corresponding experimental results to explore the characteristics and sources of errors.(4)Simulation and experimental verification of residual stress on the surface of titanium alloy blade after belt grinding.Firstly,the abrasive belt grinding experiment platform of aeroengine titanium alloy blade was built.Secondly,by comparing the results of the blade grinding experiment and the sheet pieces experiment,analyzed the difference of residual stress between the two parts and find out the reasons for its formation,and the shape compensation coefficient is obtained to realize the conversion from the simulation model of titanium alloy thin-walled parts to the simulation model of titanium alloy blades.Finally,the converted simulation results of the two characterization models are compared with the experimental results,the error sources are explored,and find out that the characterization model of residual stress on the surface of aeroengine titanium alloy blades after grinding based on molecular dynamics is determined to be more accurate and stable. |
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