Simulation Of Surface Integrity And Deformation Of Titanium Alloy Blade Strengthened By Shot Peening

In recent years,light thin-walled parts with high structural integrity,high specific strength and good sealing performance have been widely used in civil aircraft,military aircraft and a new generation of launch vehicles.In the actual service process,aircraft structural components often bear cyclic load and fatigue failure occurs.Surface shot peening has become one of the most important technical means to improve the fatigue resistance of components.However,thin-walled parts are easy to deform after shot peening,which will seriously affect the subsequent assembly and even lead to out of tolerance scrapping.The problem of evaluating and predicting the deformation of parts after shot peening has attracted much attention in the industry.The process of evaluating the deformation of parts after shot peening by experimental trial and error method is complex and costly.Exploring the use of numerical simulation calculation and analysis method has become the focus of research.In this paper,a new random multi shot peening strengthening model is established by using the coupling method of finite element and discrete element(FEM-DEM)in ABAQUS software to simulate the peening strengthening process of thin-walled structural parts,analyze the residual stress,surface roughness and overall deformation of thin-walled parts,and compare the simulation results with the experimental results to verify the effectiveness of the model.The effects of different shot peening parameters on the surface integrity of titanium alloy blades were studied.The inherent strain method is used to simulate and predict the shot peening residual stress field and deformation of large-size thin-walled blades.The main results are as follows:(1)The FEM-DEM random shot peening model has good effectiveness.The simulation of shot peening for Almen strip is consistent with the trend of residual stress curve.The maximum error of residual stress characteristic value is 11.31%,the maximum error of surface roughness is 6.78%,and the simulation accuracy of deformation value can reach 95%.(2)The established fem-dem model is used to simulate the shot peening process of TC4 blade.The results show that,with the increase of shot peening speed,the residual stress moves down and to the right along the distribution curve in the thickness direction,the blade surface roughness increases obviously,and the deformation displacement of the blade increases gradually.The increase of shot size will lead to the increase of maximum residual compressive stress depth and residual compressive stress field depth.The maximum residual compressive stress first increases and then decreases.When the projectile diameter is 0.8 mm,there is a maximum value of-866 MPa.With the increase of shot flow rate,the surface residual compressive stress and maximum residual compressive stress increase,and the depth of maximum residual compressive stress and residual compressive stress layer have no obvious change.Different shot peening paths will also lead to different shot peening strengthening effects.The value of residual compressive stress obtained when the nozzle moves parallel to the tenon root is large,the blade surface roughness is the smallest,and the blade deformation degree is small.It is the best path among the three shot peening paths.(3)The inherent strain model is in good agreement with the direct shot peening model,which can replace the random shot peening model to analyze the residual stress field and deformation of parts.The residual stress and deformation of TC4 blade strengthened by shot peening are simulated and predicted by using the inherent strain model.The results show that,under the same shot peening intensity,the distribution curves of residual stress along the thickness direction of blades with different sizes basically coincide.The deformation trend of small-size blades is the same as that of blades,while the deformation trend of large-size blades is opposite to that of blades.With the increase of blade thickness,the depth of residual compressive stress layer increases from 169 μm increased to 186 μm.Both the surface residual compressive stress and the maximum residual compressive stress increase,and the overall deformation degree of the blade decreases.