ECCOMAS 2024

A Pragmatic Overhang Minimization Approach Within a Hybrid Level-set and Density-based Topology Optimisation

  • Leclerc, Julien (Cenaero)
  • Kuci, Erin (Cenaero)

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Coupled to the additive manufacturing, topological optimization helps engineers to imagine efficient and innovative possibilities of design. However, this larger flexibility must not hide the constraints linked to the industrialization of such a manufacturing process. Specific design rules must be included in the design phase to improve the quality and the productivity in the development chain. This work aims at presenting a coupling strategy between the topology optimisation and the printing phase preparation to maximize the part printability. The optimization problem is modelled thanks to a hybrid method using density-based and level-set XFEM approaches [1]. Moreover, additional manufacturing constraints are integrated into the problem such as minimal feature size induced by the printing resolution, maximal size to avoid overheating, closed cavities constraints and the control of the overhang surfaces to limit the use of supports. This latter is still challenging in an industrial context. A similar approach to [2] is used as it is fast and applicable on large 3D irregular meshes. However, such methods are subject to the socalled dripping effect. To mitigate this effect, a pragmatic solution inspired by [3] is presented here by combining different filter characteristic sizes. Coupled to a parametric surrogate-assisted optimization (performed by our in-house optimization software Minamo) and fast geometrical analyses (performed by our in-house software Cafeine) to prepare the printing, this framework is applied on an industrial case involving eigenfrequency optimization. The impact on the part performances and its printability is also studied. REFERENCES [1] M. Jansen. Explicit level set and density methods for topology optimization with equivalent minimum length scale constraints, Structural and Multidisciplinary Optimization, 59(5)-1775-1788, 2019. [2] Y. Wang, J. Gao, Z. Kang. Level set-based topology optimization with overhang constraint: Towards support-free additive manufacturing, Computer Methods in Applied Mechanics and Engineering, 339:519-614, 2018. [3] A. Garaigordobil, R. Ansola, I. Fernandez de Bustos, On preventing the dripping effect of overhang constraints in topology optimization for additive manufacturing. Struct Multidisc Optim 64, 4065–4078, 2021.