A regional averaging method for predicting peen forming effectiveness using combined finite element simulations

To accurately predict the peen forming effectiveness under different parameters, coverage and paths, a regional averaging method is proposed in this paper. The realistic peening stress is estimated based on the average stress of all nodes in a specific area and introduced into the peening area as the initial stress to obtain the resultant shape of the sheet. On the basis of the saturated peening field, an analytical expression is proposed for calculating the average stress considering the interaction between projectiles. And the bending moment is acquired by integrating the stresses on the cross-sectional indentation. Moreover, a series of finite element models are adopted to obtain the accurate average stress. Using a Python script, the finite element models are divided into several regions and the average stress of each region is calculated separately. Through single- and four-shot models, the average stress field around a single shot and the interaction between shots are investigated. And with random peening models, the quantitative relationship of the average stress with respect to the peening intensity and coverage is revealed. In addition, the averaged stresses are introduced to sheet forming models to predict the peen forming effectiveness. Narrow strip experiments are designed under the same peening conditions as that of the sheet forming models, and the simulated values are in good agreement with experimentally measured resultant curvatures.