激光喷丸成形轴线几何效应解析建模

Analytical modeling of axis geometry effect in laser peen forming

激光喷丸成形作为一种基于单脉冲激光冲击累积效应的无模柔性成形技术,成形中几何效应对于弯曲变形量的影响直接关系到成形精度控制.轴线几何效应是复杂型面成形几何效应的重要组成部分,其对弯曲变形的影响缺乏有效的分析方法.基于圆弧轴线梁变形假设,通过激光喷丸成形等效弯曲分析方法,建立轴线几何效应分析解析模型,实现弯曲方向轴线几何效应的分析.通过激光喷丸成形固有应变数值模型验证表明,该模型能够有效反映轴线初始几何特征对于激光喷丸弯曲变形的影响;计算结果准确性与初始轴线圆弧半径有关;初始轴线圆弧半径较小时,误差相对较大.轴线初始半径对于激光喷丸弯曲变形影响较大,不同轴线初始半径分析结果表明,轴线初始半径增大时,轴线初始半径的几何效应逐渐减小.

Laser peen forming(LPF)is a novel flexible process by utilizing pulse laser to induce mechanical deformation on the specimen surface.It is of great importance to quantitatively evaluate the geometry effect on deforming behavior in LPF for both shape forming and distortion correction.This is very helpful for process planning to improve the shaping efficiency and accuracy.In this study,analytical modeling and numerical simulation are carried out to investigate the geometry effect of axis with a simplified shape.Considering that plate deformation by uniformed LPF can be assumed as beam bending with an arc shape,an analytical model is proposed to analyze its geometry effect by utilizing equivalent bending moment.The model is validated by the numerical model of LPF developed based on the eigenstrain.The result shows the developed analytical model can provide a consistent prediction of axis geometry effect,but the accuracy is depending on the initial radius of axis arc.By using the analytical modeling of LPF,the bending characteristic of LPF on the double curvature plate is studied.The prediction is more accurate when the radius of axis arc is large.When the radius of axis arc is less than 5000 mm,the axis has some effect on the bending of LPF,with the increase of the axis radius,the geometry effect of axis is gradually decreased.