中文摘要：

针对单道多层的直薄件激光立体成形过程,建立了基板预变形和无预变形条件下的3D参数化有限元模型,进行了应力和变形的瞬时热弹塑性有限元模拟分析。模拟结果表明,基板预变形处理影响成形件应力和变形的分布与大小,并可减轻基板的翘曲变形。预变形下基板下表面具有初始拉应力点的残余应力值比无预变形要小,基板与熔覆层接触的界面中间位置残余应力也小于无预变形的情况,直薄壁件最大残余压应力所在位置也发生变化。在两模型中,熔覆层两侧边缘位置变形严重,而中间位置变形较小。熔覆层首层的沉积对基板变形量影响最大,后续熔覆层的沉积对基板变形量影响程度逐渐减小并最终趋于稳定。成形前对基板进行适当的预变形处理可以有效控制成形件变形和改善应力分布。

英文摘要：

Finite element method（FEM） models are established to perform transient thermo-elastic-plastic FEM analysis on stress and deformation of single-pass multilayer with and without substrate pre-deformation during laser solid forming（LSF）.Simulation results show that substrate with pre-deformation can affect the distribution and size of stress and deformation in formed parts which can effectively alleviate the warpage of substrate.The point with initial tensile stress on the bottom surface of substrate has a smaller residual stress than that of the substrate without pre-deformed.The middle position of the interface between the substrate and the cladding layer also has a smaller residual stress than that of the substrate without pre-deformation.In both models,the positions of maximum residual compressive stress are different.Both sides of cladding layers deform badly compared with the middle location.The first cladding layer has the largest effect on substrate deformation;the deformation of the substrate gradually reduces as the cladding process proceeds.The longitudinal displacement change rate of the substrate constantly reduces and eventually tends to stable.Appropriate pre-deformation of the substrate before LSF can effectively control deformation of the substrate and improve stress distribution of the part.