铝合金喷丸工艺参数-表面特征值的函数关系与应用

目的 探究喷丸强化工艺后铝合金材料表面性能的变化规律，得到材料表层应力和变形与喷丸工艺参数间的对应关系。方法 采用Box-Benhnken实验设计法（BBD），以喷丸压力、丸粒大小、喷射距离三因素为自变量，以表面残余应力与弹坑变形量为响应，设计了3因素3水平喷丸实验方案，并运用有限元仿真软件ANSYS/LS-DYNA建立多弹丸撞击铝合金靶材的有限元模型，依据实验方案获得表面应力值与弹坑处变形量。然后，使用Design-Expert软件对数值进行拟合，得到多元回归二次方程，运用响应面分析法（RSM）进行分析，讨论各因素之间的交互作用，同时，根据回归方程的方差分析结果，确定模型的拟合程度。最后，以7075-T651铝合金为靶材，进行喷丸验证实验，结合XRD应力测试与弹坑剖面光学显微观察，得到应力值和变形量，以检验模型的准确性。结果 应力函数模型和变形函数模型的校正决定系数Adjusted R2分别为90.13%、91.68%，应力计算值和实验值结果偏差小于5.5%；剖面晶粒变形显示靶材变形层与计算值吻合较好，表明函数模型具有较高的准确性。结论 该函数模型能够快速准确地由材料表面应力或变形推导出喷丸工艺参数配置，这为喷丸表面应力和硬度强化提供多样性参考。

Function Relationship between Shot Peening Parameters and Surface Characteristic of Al-based Alloy and Application

The work aims to study the change rule of the surface properties of aluminum alloy after shot peening, and obtain the corresponding relationship between the surface material characteristics and SP parameters. Firstly, Box-Benhnken design method (BBD) was used to design 3-level and 3-factor shot peening experiment with shot peening pressure, projectile size and jet distance as independent variables and the surface residual stress and deformation as responses. The FEM of multi-projectile impact aluminum alloy sample was established by ANSYS/LS-DYNA. The surface stress and the deformation at the crater were obtained according to the experiment. Then, Design-Expert software was adopted to fit the values to obtain the multiple regression quadratic equations, and the response surface methodology (RSM) was used to analyze the interaction between the various factors. At the same time, according to analysis of variance of the function models, the degree of model-fitting was identified. Finally, with the 7075-T651 aluminum alloy as the sample, the shot peening test was carried out. Combined with the XRD stress test and the optical microscopic observation of the crater section, the stress value and the deformation value were obtained to verify the accuracy of the model. The adjusted R2 of the stress function model and the deformation function model were 90.13% and 91.68%, respectively. The deviation between calculated stress value and experimental value was less than 5.5%. The deformation of the section showed that the deformed layer of the sample was approximately the same as calculation value. The result indicated that function model had high accuracy. The function model can quickly and accurately deduce the parameter combination of the SP from the surface stress or deformation of the material, which provides a diversity reference for the surface stress and hardness strengthening of SP.