Numerical Simulation For Compressive Residual Stress And Surface Morphology Of Shot Peening Based On Sph Method

Shot peening is a surface strengthening technology widely used in industrial areas which can improve the fatigue strength of components. The mechanism of shot peening is very complex and influenced by many factors. X-ray stress analysis and blind-hole method are the main experimental ways to measure the residual compressive stress. All these ways will damage the component and need high cost and low sufficiency. The operation is also complex and unintuitive. However, numerical simulation can provide an economic and sufficiency way to study the shot peening process. Traditional way based on the finite element method can just simulate the process of single and few shot peening. Therefore, smoothed particle hydrodynamics (SPH) method coupled the finite element method (FEM) is applied as a new modeling way to simulate angular particle influence on the surface morphology and plenty of shot peening in this article. More practical simulation results will be got in this paper.Firstly, SPH coupled FEM is applied to study rotating effects and surface morphology of the angular particle impacting with different incidence angles and rake angles in this section. The results show that the particle will rotate forward when its rake angle is large enough. The angular crater will be formed and chips will pile up at the edge of the crater without separating from the work piece. On the other hand, the particle will rotate backward when its rake angle is small. A shallow and smoothed crater will be formed and chips would separate from the work piece. The relationship among the incidence conditions, crater depths and chips pile-up heights are also investigated. The simulation model and results are validated by the existing theoretical and experimental data.Secondly, the FEM method is used to investigate factors influence on the compressive residual stress and surface morphology by few particles. Design an orthogonal experiment with velocity, size and overlap rate as its three key factors. Range analysis is used to find the optimum parameter combination and variance analysis is used to investigate the most significant factor influence on the depth of compressive residual stress. The conclusion can be used to guide to choose more reasonable technological parameters of shot peening.Thirdly, SPH coupled FEM are used to investigate the process of plenty of particles impacting the target surface. FEM method is used to model the workpiece, while SPH method is used to model the mixed projectile flow; they are coupled by contact algorithm. Modeling strategy of the mixed projectile flow using SPH method is explored. Semi empirical formula is used to derive the equation of state (EOS) of the mixed projectile flow. How particle velocity, impact frequency and coverage influence on the compressive residual stress are also investigated.