Abstract
Additive manufacturing (AM) has significant advantages in fabricating complex structures designed by topology optimization (TO). However, AM is also well-known to be plagued by overhang issues, which are usually partially solved by adding a large amount of sacrificial supports during printing. This paper proposes an effective method to eliminate supports at the TO stage by incorporating overhang angle and minimum feature size constraints into the TO problem formulation along with the regular volume constraint. Being used to establish the overhang angle constraint, overhang angles in the structures with blurry boundaries in solid isotropic materials with penalization (SIMP) are estimated as the angle between the horizontal direction and the density contour which is fitted by extracting the density of the element at the structure boundaries. A density numerical relationship is constructed between adjacent elements in the horizontal direction to limit the generation of too small size features. Structures can directly be manufactured with no requirement of sacrificial support material right after the proposed TO process. The structural TO problem is solved by the method of moving asymptotes (MMA). Numerical examples and experiments are given to demonstrate the capacities of the presented algorithm.
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Data availability
The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. For any interested reader, we can provide the STL files of the designed beams by proposed method. For peer reviewers, the data used to support the findings of this study are available from the corresponding author upon request.
Code availability
The code required to reproduce these findings cannot be shared at this time as the code also forms part of an ongoing study. For peer reviewers, the code is available from the corresponding author upon request.
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Funding
This work was supported by the Natural Science Foundation of Hebei Province (E2018203403/ E2021203185), the Fundamental Research Funds for the Central Universities (30917014101), and the Youth Foundation of Hebei Educational Committee (QN2018228).
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Conceptualization: JC and JC; Methodology: JC and JC; Formal analysis and investigation: JC, XZ, and JW; Writing—original draft preparation: JC; Writing—review and editing: JC, JC, JW, and CZ Funding acquisition: JC; Resources: JC; Supervision: JC.
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Replication of results
Please contact Prof. Krister Svanberg for MMA (optimization algorithm). The code listings for the SIMP (density-based topology optimization method) can be downloaded at https://github.com/williamhunter/topy. And the details about the SIMP can be found in Bendsøe (1989). The code listings for the filtering method are available in Bourdin (2001) and Xu (2009). The necessary information for replication of the results is presented in this paper. The interested reader may contact the corresponding author for further implementation details.
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Chen, J., Cheng, J., Zhang, X. et al. An additive manufacturing-oriented structural optimization design method to eliminate sacrificial support. Struct Multidisc Optim 65, 230 (2022). https://doi.org/10.1007/s00158-022-03298-7
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DOI: https://doi.org/10.1007/s00158-022-03298-7