An Open Source Framework for Integrated Additive Manufacturing and Level-Set-Based Topology Optimization

Abstract

Topology optimization has been considered as a promising tool for conceptual design due to its capability of generating innovative design candidates without depending on the designer's intuition and experience. Various optimization methods have been developed through the years, and one of the promising options is the level-set-based topology optimization method. The benefit of this alternative method is that the design is characterized by its clear boundaries. This advantage can avoid postprocessing work in conventional topology optimization process to a large extent and realize direct integration between topology optimization and additive manufacturing (AM). In this paper, practical algorithms and a matlab-based open source framework are developed to seamlessly integrate the level-set-based topology optimization procedure with AM process by converting the design to STereoLithography (STL) files, which is the de facto standard format for three-dimensional (3D) printing. The proposed algorithm and code are evaluated by a proof-of-concept demonstration with 3D printing of both single and multimaterial topology optimization results. The algorithm and the open source framework proposed in this paper will be beneficial to the areas of computational design and AM.

Current and future trends in topology optimization for additive manufacturing

“…Generally after topology optimization, either the density [260] or level set field [261] needs to be postprocessed into a printer-compatible geometric file, e.g., the STL. As a boundary-based geometric model, level set methods not only provide a clear representation of the boundary but also embed higher order geometric information, such as the normal vectors or curvatures.…”

“…As a boundary-based geometric model, level set methods not only provide a clear representation of the boundary but also embed higher order geometric information, such as the normal vectors or curvatures. Such information can be utilized to create a seamless connection between the design and fabrication process [261]. This is important in the Top view Bottom view Part of the faces to be machined topology optimization-driven design innovation, where the organic conceptual design often needs postprocessing such as CAD reconstruction before it can be manufactured.…”

“…The data of all the facets must be stored in a file with STL (Stereolithography) format, a standard format widely recognized by the 3D printers and CAD software. Open-source codes are available for generating STL files based on topology optimization results [260,260,261,264]. Wang developed methods in [A1, A2] to extract surface meshes from implicitly represented volumes, and a parallelized algorithm for mesh generation was proposed in [A3].…”

“…Level-set-based framework for integrated TO and AM[261] . (a) unit cell design, (b) 3x3 structure design, (c) separate design for each material, (d) meshed surface, and (d) 3d printed prototype…”

Computational Design and Additive Manufacturing of Conformal Metasurfaces by Combining Topology Optimization With Riemann Mapping Theorem

“…If a 3D topology optimization is followed, the result would be a 3D metamaterial with specific effective properties. Either way, the design must be translated into a triangle mesh so the communication between all the steps can be possible [50]. The design, now, is a set of triangular facets described by three vertices for the points and one normal vector, each.…”