Self-supporting structure design for additive manufacturing by using a logistic aggregate function

• Published in: Structural and multidisciplinary optimization Vol. 60; no. 3; pp. 1109 - 1121
• Main Authors: Kuo, Yu-Hsin, Cheng, Chih-Chun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2019; Springer Nature B.V
• Subjects: Additive manufacturing; Cantilever beams; Computational Mathematics and Numerical Analysis; Continuity (mathematics); Deposition; Design for manufacturability; Domains; Engineering; Engineering Design; Fused deposition modeling; Research Paper; Sensitivity analysis; Supports; Theoretical and Applied Mechanics; Topology optimization; Topology optimization; Overhang angle; Manufacturing constraint; Design for manufacturability; Support-free
• ISSN: 1615-147X; 1615-1488
• DOI: 10.1007/s00158-019-02261-3

Self-supporting designs that eliminate the need for structural supports can reduce manufacturing complexity caused by overhanging parts in additive manufacturing (AM). Traditionally, 45° is the minimum overhang angle required to ensure that designs can be manufactured without requiring any supporting structure. In this paper, a new self-supporting design method of AM based on topology optimization with overhang angle constraint is proposed. A self-supporting index established using a continuous logistic aggregate function is introduced to assess the supporting status of the specimen for AM process. This proposed self-supporting index is continuous and can be directly differentiated for sensitivity analysis without further mathematical transformations in the optimization formulation. Furthermore, it can be easily extended to a high-dimension aggregate (i.e., it can easily adapt to different overhang angles or self-supporting design domains). Numerical and fused deposition modeling (FDM) of a cantilever and MBB beam reveal that the self-supporting design can satisfy either general overhang angles or arbitrary orientation of AM deposition direction.