Metal additive manufacturing (AM) processes often fabricate a near-net shape that includes the as-designed part as well as the sacrificial support structures that need to be machined away by subtractive manufacturing (SM), for instance multi-axis machining. Thus, although AM is capable of generating highly complex parts, the limitations of SM due to possible collision between the milling tool and the workpiece can render an optimized part non-manufacturable. We present a systematic approach to topology optimization (TO) of parts for AM followed by SM to ensure removability of support structures, while optimizing the part's performance. A central idea is to express the producibility of the part from the near-net shape in terms of accessibility of every support structure point using a given set of cutting tool assemblies and fixturing orientations. Our approach does not impose any artificial constraints on geometric complexity of the part, support structures, machining tools, and fixturing devices. We extend the notion of inaccessibility measure field (IMF) to support structures to identify the inaccessible points and capture their contributions to non-manufacturability by a continuous spatial field. IMF is then augmented to the sensitivity field to guide the TO towards a manufacturable design. The approach enables efficient and effective design space exploration by finding nontrivial complex designs whose near-net shape can be 3D printed and post-processed for support removal by machining with a custom set of tools and fixtures. We demonstrate the efficacy of our approach on nontrivial examples in 2D and 3D.

中文翻译：

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具有无障碍支撑结构的制造拓扑优化

金属增材制造 (AM) 工艺通常会制造出近净形状，其中包括设计零件以及需要通过减材制造 (SM) 加工掉的牺牲支撑结构，例如多轴加工。因此，虽然 AM 能够生成高度复杂的零件，但由于铣刀和工件之间可能发生碰撞而导致 SM 的局限性可能导致优化的零件无法制造。我们提出了一种系统方法，用于 AM 和 SM 零件的拓扑优化 (TO)，以确保支撑结构的可拆卸性，同时优化零件的性能。一个中心思想是使用一组给定的切削工具组件和夹具方向，根据每个支撑结构点的可接近性，从近净形状中表达零件的可生产性。我们的方法不会对零件、支撑结构、加工工具和夹具的几何复杂性强加任何人为约束。我们扩展了不可访问性度量域 (IMF) 的概念，以支持结构以识别不可访问点并通过连续空间场捕获它们对不可制造性的贡献。然后将 IMF 增加到灵敏度领域，以引导 TO 实现可制造的设计。该方法通过寻找非平凡的复杂设计来实现高效和有效的设计空间探索，这些设计的近净形状可以进行 3D 打印和后处理，以通过使用一组自定义工具和夹具进行加工来去除支撑。我们证明了我们的方法对 2D 和 3D 中非平凡示例的有效性。