超声冲击残余应力场的有限元模拟

Finite Element Simulation of Residual Stress Field Induced by Ultrasonic Impact Treatment

建立模拟超声冲击残余应力场的三维有限元模型,预测AISI 304奥氏体不锈钢靶材经超声冲击后的残余应力场分布。模拟过程中,分析冲击速度、针头直径、冲击时间、摩擦力、冲击次数以及不同覆盖率等因素对超声冲击残余应力场分布影响的规律。结果表明,冲击速度、针头大小、冲击时间及摩擦力都会影响到最终冲击残余应力场。冲击速度和针头直径对残余应力场分布影响显著,速度提高或直径变大,均可明显提高残余压应力值,且增加残余压应力层深度,但摩擦系数对冲击效果的影响不大。随着冲击次数的增加,超声冲击强化特征明显,残余压应力层深度增加。随着覆盖率的增加,残余压应力层增厚,但形成的最大残余压应力值减小。

A 3D finite element model predicting the residual stress distribution induced by ultrasonic impact treatment（UIT） in the AISI 304 stainless steel was established.Effects of impact velocity,pin size,impact time,interfacial friction,multiple impacts and coverage were considered during the simulation.The results show that impact velocity,pin size,impact time and interfacial friction affect the final residual stress field.Impact velocity and pin diameter have a great influence on the distribution of residual stress field.The depth of the stress layer and the residual stress value increase along with the rising of pin diameter or impact velocity.However,friction coefficient has little influence on impact.According to the increase of impact time,the ultrasonic impact strengthening characteristic is obvious and the depth of the stress layer increases.Along with the increase of the coverage,the compressive residual stress layer gets thicker,but the formation of the maximum compressive residual stress value decreases.