Study Of Elastic Plastic Behavior In Water Cavitation Peening Processing

As a new material surface strengthening technology, water-jet cavitation peening(WCP) technology is different from the traditional mechanical shot peening and other existing shot peening process, the principle of strengthening is rational and efficient use of submerged high pressure and high speed water-jet with a large number of small bubbles, and adjust the distance of the target and the nozzle,make bubbles collapse near or on the surface of target and form the pressure shock wave propagated into the target, thus induce compressive residual stress on the surface of the target in a certain depth and achieve the purpose of strengthening. Although elastic-plastic deformation induced by WCP was studied both at home and abroad, but the research results lackluster. In order to conduct a comprehensive study about the elastic-plastic deformation induced by WCP, numerical simulation and experimental study on the residual stress and plastic deformation induced by WCP under different parameters are carried out:From the relevant theoretical knowledge to WCP, briefly introduces the cavitation phenomenon 、 cavitation bubble dynamics and cavitation damage mechanism; analyzes sheet metal dynamic response with the impact of shock wave and the mechanism of compressive residual stress generation and plastic deformation induced by WCP, and effect of different factors on the residual stress field distribution and the elastic plastic deformation. Using GAMBIT software, the two-dimensional spherical bubble calculation model which attached to the wall surface is established. Besides, the changes in shape, the pressure field and micro-jet velocity field during spherical bubble collapse process are simulated through the FLUENT fluid calculation software, and then analyze the gain results. The residual stress and deformation induced by WCP are simulated with the help of software ANSYS / LS-DYNA, and several key issues in the process of establishing the model are discussed(pressure loading, material constitutive model, mesh generation, boundary setting and solution setting); mainly study four factors’ effect on the compressive residual stress field and plastic deformation which are the type of material, plate thickness, loading curve and impact pressure, and gain the change law of compressive residual stress and plastic formation under these parameters.On the basis of numerical simulation, the experimental study on N type standard Almen test strip is carried out by equipment of WCP, and the compressive residual stress and arc height are measured by X- ray stress tester and the Almen gauge respectively, the comparison between the experimental data and the simulation results shows that there is good agreement between them, which indicates the finite element method can be used to predict the compressive residual stress field and plastic deformation of the sheet metal. The above research results have certain reference value to the application of the WCP technology and the optimization of the process parameters.