基于瞬态有限元分析的薄壁结构扫描路径优化

Scanning Path Optimization of Thin-Walled Structures Based on Transient Finite Element Analysis

摘要: 选择性激光熔化(Selective laser melting, SLM)是一个复杂的过程，涉及到金属的固–液转换、热传导、热辐射等过程，其成型零部件的翘曲变形一直是影响零件成型精度，制约SLM技术发展的主要原因。薄壁零件由于升温和散热较快，温度场分布非常不均匀，更容易发生翘曲变形。为保证SLM过程的正常进行并提高薄壁零件的成型精度，必须有效控制其温度场的分布。本文基于ANSYS软件中APDL语言对SLM加工过程中的简单薄壁结构进行了温度场、应力场和翘曲变形的瞬态有限元分析，建立了薄壁结构件模型，分析比较了不同扫描成型方式对其成型精度的影响。针对薄壁结构件对比了六种扫描方式多层成型的温度场和应力场，并比较了不同扫描成型方式下薄壁结构件翘曲变形量的大小。探究了温度梯度、内应力和翘曲变形之间的联系，从整个成型过程分析了影响零件成型精度的机理，并提出了一种针对薄壁结构的分层组合式扫描成型方式。

Abstract: Selective laser melting (selective laser melting, SLM) is a complex process, which involves the process of metal solid-liquid conversion, heat conduction, heat radiation, and so on. The warping deformation of molded parts has always been the main reason for influencing the forming precision of parts and restricting the development of SLM technology. Because of fast heating and heat dissipation of thin-walled parts, the distribution of temperature field is very uneven, which is more prone to warping deformation. In order to ensure the normal process of SLM and improve the forming precision of thin-walled parts, the distribution of temperature field must be controlled effectively. In this paper, based on the APDL language in ANSYS software, the transient finite element analysis of temperature field, stress field and warping deformation of the simple thin-walled structure in SLM processing was performed. The thin-walled structure model was es-tablished. The temperature field and stress field of multi-layer forming in six scanning modes were compared, and the warping deformation of thin-walled structures in different scanning modes was also compared. The relationship between temperature gradient, internal stress and warping deformation was investigated, and the mechanism affecting the forming precision of parts was analyzed from the whole forming process. According to the above, a kind of combination scanning forming method for thin-wall structure was proposed.