喷丸残余应力场有限元模拟研究进展

喷丸强化处理工艺可以显著提高金属材料的抗疲劳和抗应力腐蚀等性能,这与喷丸后在金属表面层形成的残余应力场紧密相关,因此对喷丸残余应力的大小及分布进行预测具有重要意义。对近年国内外喷丸残余应力场的有限元模拟进行评述,总结出6种典型的残余应力分析模型,分别是二维轴对称模型、四对称面模型、三对称面模型、双对称面模型、单对称面模型和无对称边界条件的有限元模型,比较了不同模型的特点及应用现状。介绍了当前几种新的残余应力分析有限元模型:随机三维模型和周期性边界条件模型,根据其原理和特点认为其本质是无对称边界条件模型和对称边界条件有限元模型的延伸。针对空化水喷丸、激光喷丸和超声波喷丸等新工艺,新喷丸过程的数值模拟一般是以机械喷丸工艺的数值模拟方法为基础进行改进,主要采用弹丸撞击法和等效载荷法。对未来喷丸残余应力数值模拟研究进行了展望,认为从组织强化角度深入研究喷丸强化机理、建立更符合实际喷丸工艺的有限元模型、开发新算法以及将有限元法和离散元法进行结合是值得关注的研究方向。

Research progress on finite element modeling and simulation of residual stress field induced by shot peening

Shot peening is a process in which a stream of spherical shot impacts on the component surface,causing plastic deformation.After contacting,the high compressive residual stress field is generated at the surface of the component.Compressive residual stress field in the surface layers greatly improves the fatigue life and stress corrosion resistance.It is therefore very useful to predict the distribution and magnitude of the residual stress.It summarized the recently development of finite element modeling and simulation of residual stresses field induced by shot peening.Six main types of finite element models were summarized as follows:2D finite element model of axis-symmetry,model of four symmetric planes,model of three symmetric planes,model of two symmetric planes,model of one symmetric plane and finite element model without symmetrical boundary conditions.These models’principals were compared and their characteristics and applications were also introduced.3D random model and the model with periodic boundary condition as new finite element model were introduced;the two models were considered essentially as extend of the finite element model without/with symmetrical boundary conditions according to their principals and characteristics.Water cavitation peening,laser shock peening and ultrasonic peening were modern processes;the simulation of these new processes was on the basis of the finite models’change of mechanical shot peening,projectile impact method and equivalent load method were used in the modeling.The outlook of future research on numerical simulation of residual stress field after shot peening was prospected.Mechanism of structure strengthening during shot peening,establishment of the finite element model that can be more in accordance with the real condition and development of new algorithms,combination of finite element and discrete element were the worthy studying directions for future efforts.