超声喷丸与传统喷丸对TC4 钛合金残余应力影响的仿真分析

为了预测喷丸TC4钛合金试件的残余压应力层深度及值的分布和冲击面凹坑的直径、深度特征曲线及表面形貌的变化,采用ABAQUS/Explicit软件建立2个3D模型。通过超声喷丸与传统喷丸2种工艺过程数值仿真对比了表面残余应力场差异,分析了TC4钛合金弹丸直径、速度和冲击次数等喷丸参数对残余应力分布的影响。结果表明:当动能相同时,2种强化过程表面所产生的残余压应力是可比较的,超声喷丸模型亚表层残余应力深度为0.16 mm,约为传统喷丸模型深度的2倍;传统喷丸产生的残余压应力最大值约-800 MPa,约为超声喷丸的1.6倍。与传统喷丸相比,超声喷丸具有较低的表面粗糙度以及较深的残余压应力层。残余压应力层深度与弹丸直径呈正相关,但过大的弹丸尺寸会引起薄壁件另一侧残余拉应力区域的增大。

Simulation Analysis of Influence of Ultrasonic and Conventional Shot Peening on Residual Stress of TC4 Titanium Alloy

In order to predict the distribution of the depth and value of the compressive residual stress layer of shot peening TC4 titanium alloy specimen and the change of diameter, depth characteristic curve and surface morphology of impact surface pit,two 3 D models were established by Abaqus/Explicit software. The difference of surface residual stress field was compared by numerical simulation of ultrasonic shot peening and conventional shot peening. The influence of shot peening parameters such as diameter,velocity and times of impact on residual stress distribution of TC4 titanium alloy projectile was analyzed. The results show that when the kinetic energy is the same,the compressive residual stress on the surface of the two reinforcing processes can be compared,and the residual stress depth of the subsurface of the ultrasonic peening model is 0.16 mm,which is about 2 times the depth of the conventional peening model. The maximum compressive residual stress of conventional shot peening is about-800 MPa,about 1.6 times that of ultrasonic shot peening. Compared with conventional shot peening,ultrasonic shot peening has lower surface roughness and deeper compressive residual stress layer. The depth of the compressive residual stress layer is proportional to the diameter of the projectile,but the size of the projectile can cause the increase of the residual tensile stress area on the other side of the thin wall.