Numeral Simulation For Compressive Residual Stress Of Shot Peening Based On SPH Method

Shot peening is a surface treating process which can effectively enhance the fatigue life of workpieces. A large compressive residual stress is formed in subsurface of the work pieces by impinging the surface of the metallic components with thousands of shots at high velocities that can ensure a good fatigue resistance to stress corrosion. However shot peening is a complex process involving modeling for a mass of discrete shots and the disciplines of dynamic plasticity. The choices of the process parameters and its arrangements have a great effect on the compressive residual stress values and its distribution. Obviously, it is also difficult to describe this process using analytical mathematical model. In order to predict the shot peening process, numerical simulations were used and existing simulation models were all based on finite element method (FEM) to investigate the relationships between the compressive residual stress and the shot peening parameters. Most existing FEM models used only a single shot or several shots (less than 9) to simulate the shot peening process, thus the effect of a mass of shots repeat impacting and the influence among adjacent shots are ignored.To overcome above defects caused by FEM, a coupled method of smoothed particle hydrodynamic (SPH) and FEM is adopted to build the numerical model to simulate the whole shot peening process. The simulation results agree well with the existing experimental data. The study will not only provide a new powerful tool for the simulation of shot peening process, but also be benefit to optimize the operating parameters.SPH method is one of mesh-free methods. Because of its Lagrange property and remarkable self-adaptability, it is easy to trace the track. To overcome these defects of FEM models, SPH coupled FEM modeling is presented, in which the shots are modeled by SPH particles and the target material is modeled by finite elements. The mixture model of shots and air is established by SPH particles and state equation. Contact algorithm is used to simulate the interaction of shots impinging target. Utilizing this model, the relationships between compressive residual stress and peening frequencies, coverage, velocities and energy utilization are analyzed. Finally, some conclusions are educed.For further research, the micro-model of single shot is established. Through the comparison of results between experiment and simulation, the validity of influence law gotten by SPH coupled FEM model is confirmed and some supplement conclusions are presented.It will be benefit to understand the shot peening mechanism and optimize the operating parameters.