Simulation Study on Mechanism of Residual Stress Field Generation in Ti6Al4V Alloy Ultrasonic Vibration Turning Based on Equivalent Thermal-force Load
The article presents a 3D finite element model of Ti6Al4V alloy ultrasonic vibration turning based on an equivalent thermal-mechanical load.The cutting process involves the cyclic interaction between mechanical and thermal effects on the workpiece surface.Numerical calculations determine the shape,intensity,and variation of force-thermal load distribution in ultrasonic vibration cutting.Experimental verification is conducted to obtain residual stresses on the surface of Ti6Al4V alloy during ultrasonic vibration turning.Based on this model,this study analyzes the influence mechanism of cool-ing and lubrication effects on three-dimensional residual stress distribution on surfaces during ultrasonic vibration turning under controlled variables such as minimal lubrication and liquid nitrogen cooling methods.The results indicate that differ-ent cooling-lubrication methods can generate residual compressive stress fields on titanium alloy surfaces,with cutting force being a major factor affecting both the magnitude and depth of residual compressive stress.The lubricating effect reduces friction between the tool and workpiece surface,decreasing cutting forces and resulting in reduced residual compressive stress.The cooling effect primarily affects the workpiece's deformation resistance by changing its material properties which indirectly influences cutting forces.Strong cooling media like liquid nitrogen significantly lowers cutting temperature,en-hances deformation resistance during machining processes leading to increased cutting forces thus causing higher residual compressive stresses on machined surfaces.
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