增材制造自支撑设计综述

Review of Self⁃Supporting Design for Additive Manufacturing

增材制造(AM)的零件若存在悬垂部件,则往往需要添加额外的支撑结构,这不仅会影响打印效率,而且拆除支撑也会引发新的问题。结构自支撑设计能使增材制造摆脱对支撑结构的依赖,现已成为国内外的研究热点。本文首先总结了增材制造结构自支撑设计的原理,接着综述了增材制造零件整体结构自支撑设计的研究进展以及增材制造填充结构自支撑设计的研究进展。其中,根据不同的结构优化方式,将增材制造零件整体结构自支撑设计进一步划分为基于连续体结构拓扑优化、离散结构拓扑优化和形状优化的结构自支撑设计,并分析了各类优化方法的优缺点。最后,讨论了提升计算效率以及提升结构性能的解决方案,并对未来的应用场景以及未来的研究重点进行了展望。

Significance Additive manufacturing can be used to construct complex structures and facilitate the design of an overall structure by adding materials layerbylayer to form parts.Additive manufacturing technology has been widely used in the automotive,electronics,aerospace,and medical fields and plays a crucial role.However,during the additive manufacturing process,parts with overhangs are often encountered and cannot be successfully printed without considering the overhangs.For traditional 2.5-axis 3D printers,two methods are used to solve the problem of overhanging structures that cannot be printed.One method involves adding support structures below the area with the overhanging structures,and the other requires achieving selfsupport of the structures through structural optimization.Adding support structures can prevent warping and reduce the structural deformation of a part.However,this method increases the production time and material costs.In addition,further postprocessing is required to remove unwanted support structures,which is timeconsuming and affects the surface accuracy of the part.Therefore,it is important to achieve selfsupport of a printed part to reduce the material cost,printing time,and postprocessing time.Progress We summarize the research progress in structural selfsupporting design for additive manufacturing.First,the principle of the structural selfsupporting design of additive manufacturing is summarized,and the research progress in the selfsupporting design of the overall structure of additive manufacturing parts and the selfsupporting design of additive manufacturing infill structures are reviewed.Based on different structural optimization methods,it is further divided into structural selfsupporting design using continuum structural topology optimization,discrete structural topology optimization,and shape optimization.Next,the advantages and disadvantages of each method are analyzed.Finally,solutions to improve computing efficiency and structural performance are discussed,along with future application scenarios and research priorities.Conclusions and Prospects Additive manufacturing of structural selfsupporting designs is critical for saving printing time and material,but it has not been systematically reviewed.This paper first summarizes the structural selfsupporting design principle of additive manufacturing and reviews the research progress of the selfsupporting design of the overall structure of the part,which is divided into three parts:research progress in structural selfsupporting design based on continuum structure topology optimization,discrete structural topology optimization,and shape optimization.Previous studies were mainly based on continuum structure topology optimization,and the research progress in structural selfsupporting design based on continuum structure topology optimization is presented in four parts:research progress in structural selfsupporting design using the SIMP method and its improved version,the level set method,the BESO method,and featuredriven optimization.Subsequently,the research progress in the selfsupporting design of additive manufacturing infill structures is reviewed.Finally,selfsupporting designs of additive manufacturing structures are summarized and discussed.The structural selfsupporting design of additive manufacturing is still in its infancy,and the following prospects are proposed to further develop this field.(1) Perform 3D case extensions. Despite the rapid development of structural selfsupportingdesign, the proposed method is still in its infancy and has been mainly applied to 2D cases based on the“ rule of thumb” of printable overhang angles. Therefore, the extension to 3D cases still requires further investigation.(2) Improve the computational efficiency of sensitivity. Previous studies were mainly based on continuum structure topology optimization, and topology optimization design has problems, such as large design variables, which often leads to high computational costs owing to the excessive number of elements in the sensitivity calculation design. Therefore, it is necessary to improve the sensitivity calculation method and increase calculation efficiency.(3) Comprehensive consideration of the overhang feature constraints, printing direction, and topological layout. Compared with considering only the overhang angle constraint, a comprehensive consideration can further reduce the loss of structural performance. Moreover, the threshold value of the overhang angle often depends on the direction of printing. Therefore, in future research, the integrated consideration of printing direction and topological layout should be the focus.(4) Combine selfsupportwith other structural properties. During the melting and solidification of metallic materials printed by additive manufacturing, residual stresses and deformations are typically induced, resulting in printing failure or a decrease in strength and dimensional accuracy. Therefore, considering a selfsupportingdesign that considers the residual stress and deformation of the structure is an important direction for future development. In addition, lightweight design is required in the aerospace field and should be considered in combination with light weight during the selfsupportingdesign process.