Topology Optimization for Manufacturing with Accessible Support Structures

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.

[1]  Saigopal Nelaturi,et al.  Exploring Feasible Design Spaces for Heterogeneous Constraints , 2019, Comput. Aided Des..

[2]  Charlie C. L. Wang,et al.  Current and future trends in topology optimization for additive manufacturing , 2018 .

[3]  Tomás Lozano-Pérez,et al.  Spatial Planning: A Configuration Space Approach , 1983, IEEE Transactions on Computers.

[4]  Saigopal Nelaturi,et al.  Topology Optimization with Accessibility Constraint for Multi-Axis Machining , 2020, Comput. Aided Des..

[5]  Anders Clausen,et al.  Efficient topology optimization in MATLAB using 88 lines of code , 2011 .

[6]  Albert C. To,et al.  Topology optimization for hybrid additive-subtractive manufacturing , 2017 .

[7]  Andrew T. Gaynor,et al.  Eliminating occluded voids in additive manufacturing design via a projection-based topology optimization scheme , 2020 .

[8]  Takao Miki,et al.  Topology optimization for considering distortion in additive manufacturing , 2020, ArXiv.

[9]  Xiaoping Qian,et al.  Simultaneous optimization of build orientation and topology for additive manufacturing , 2020 .

[10]  Xiaoping Qian,et al.  Undercut and overhang angle control in topology optimization: A density gradient based integral approach , 2017 .

[11]  Charlie C. L. Wang,et al.  Self-supporting rhombic infill structures for additive manufacturing , 2016, Comput. Aided Des..

[12]  O. Sigmund,et al.  Minimum length scale in topology optimization by geometric constraints , 2015 .

[13]  Francesco Iorio,et al.  A subtractive manufacturing constraint for level set topology optimization , 2020, Structural and Multidisciplinary Optimization.

[14]  Lin Cheng,et al.  On utilizing topology optimization to design support structure to prevent residual stress induced build failure in laser powder bed metal additive manufacturing , 2019, Additive Manufacturing.

[15]  Ehsan Malekipour,et al.  Heat Conduction and Geometry Topology Optimization of Support Structure in Laser-Based Additive Manufacturing , 2018 .

[16]  Deepak K. Gupta,et al.  Automated and Accurate Geometry Extraction and Shape Optimization of 3D Topology Optimization Results , 2020, ArXiv.

[17]  Grégoire Allaire,et al.  Structural optimization under overhang constraints imposed by additive manufacturing technologies , 2017, J. Comput. Phys..

[18]  Ole Sigmund,et al.  A 99 line topology optimization code written in Matlab , 2001 .

[19]  Krishnan Suresh,et al.  A Review of Methods for the Geometric Post-Processing of Topology Optimized Models , 2020, J. Comput. Inf. Sci. Eng..

[20]  Hung Nguyen-Xuan,et al.  Extruded-geometric-component-based 3D topology optimization , 2020 .

[21]  Mingdong Zhou,et al.  Topology optimization of easy-removal support structures for additive manufacturing , 2020 .

[22]  Shigeru Aomura,et al.  Topology Optimization for the Extruded Three Dimensional Structure with Constant Cross Section , 2004 .

[23]  Krishnan Suresh,et al.  Support structure constrained topology optimization for additive manufacturing , 2016, Comput. Aided Des..

[24]  Grégoire Allaire,et al.  Taking into account thermal residual stresses in topology optimization of structures built by additive manufacturing , 2018, Mathematical Models and Methods in Applied Sciences.

[25]  Jikai Liu,et al.  Role of anisotropic properties on topology optimization of additive manufactured load bearing structures , 2017 .

[26]  F. Haas,et al.  Direct Machining of selective laser melted components with optimized support structures , 2019, Procedia CIRP.

[27]  J. Plocher,et al.  Review on design and structural optimisation in additive manufacturing: Towards next-generation lightweight structures , 2019 .

[28]  James K. Guest,et al.  Imposing maximum length scale in topology optimization , 2009 .

[29]  Saigopal Nelaturi,et al.  Optimizing Build Orientation for Support Removal using Multi-Axis Machining , 2021, Comput. Graph..

[30]  O. Sigmund Morphology-based black and white filters for topology optimization , 2007 .

[31]  Vadim Shapiro,et al.  Group morphology with convolution algebras , 2010, SPM '10.

[32]  Shutian Liu,et al.  Topology optimization design of cast parts based on virtual temperature method , 2018, Comput. Aided Des..

[33]  Yongsheng Ma,et al.  A survey of manufacturing oriented topology optimization methods , 2016, Adv. Eng. Softw..

[34]  D. Tortorelli,et al.  A geometry projection method for continuum-based topology optimization with discrete elements , 2015 .

[35]  Lothar Harzheim,et al.  A review of optimization of cast parts using topology optimization , 2005 .

[36]  W. Hintze,et al.  Finish machining of Ti6Al4V SLM components under consideration of thin walls and support structure removal , 2020, Procedia Manufacturing.

[37]  T. Simpson,et al.  Milling of Inconel 718 block supports fabricated using laser powder bed fusion , 2018, Journal of Manufacturing Processes.

[38]  Valmik Bhavar,et al.  A review on powder bed fusion technology of metal additive manufacturing , 2017 .

[39]  Matthijs Langelaar,et al.  Topology optimization for multi-axis machining , 2019, Computer Methods in Applied Mechanics and Engineering.

[40]  Xun Xu,et al.  Support Structures for Additive Manufacturing: A Review , 2018, Journal of Manufacturing and Materials Processing.

[41]  Amir M. Mirzendehdel,et al.  Strength-Based Topology Optimization for Anisotropic Parts , 2018 .

[42]  Matthijs Langelaar,et al.  Topology optimization of 3D self-supporting structures for additive manufacturing , 2016 .

[43]  Krishnan Suresh,et al.  Build optimization of fiber-reinforced additively manufactured components , 2020, Structural and Multidisciplinary Optimization.

[44]  T. Dbouk,et al.  A review about the engineering design of optimal heat transfer systems using topology optimization , 2017 .

[45]  O. Sigmund,et al.  Additive manufacturing oriented topology optimization of structures with self-supported enclosed voids , 2020 .