2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Applications: Topology Optimization
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 8:00 AM
August 16, 2023
Room: 416 AB
Location: Hilton Austin
Session Chair: Mehran Tehrani, Conference Chair, University of California, San Diego
8:00 AM
Topology Optimization of Continuous Fiber-reinforced Composites Considering Manufacturing Constraints: Janet Wong1; Emily Sanders1; David Rosen1; 1Georgia Institute of Technology
Additive manufacturing (AM) has enlarged the design space of variable stiffness and continuous fiber-reinforced composites (FRCs) by enabling increased freedom in the geometric layout of continuous fibers. Fiber layout optimization has been integrated with topology optimization (TO) to harness such design freedom; however, additional constraints are needed to ensure manufacturability in extrusion-based AM of continuous FRCs. We directly integrate constraints on fiber path curvature and gaps/overlaps between fiber paths into the TO framework. Alongside density design variables defining the structure’s topology, we define radial basis functions (RBFs) with fiber angle design variables defined on the RBF support points. The RBFs promote fiber path continuity and allow us to define functions related to their curl and divergence, which we use as differentiable manufacturing constraints on curvature and gaps/overlaps, respectively. Several numerical examples are provided to illustrate tradeoffs between structural performance and manufacturability of optimized, continuous FRCs when such constraints are considered.
8:20 AM
Off the Grid: Re-defining Design Resolution in Inkjet 3D-printing for Sub-droplet Position Control and Facile Geometry Improvement: Oliver Nelson-Dummett1; Geoffrey Rivers1; Negar Gilani1; Marco Simonelli1; Christopher Tuck1; Richard Hague1; Ricky Wildman1; Lyudmila Turyanska1; 1University of Nottingham
Inkjet 3D printing (IJ3DP) is critical technology for next generation multi-material or graded-material printed devices. IJ3DP patterns mainly utilise per-layer bitmaps, traditionally selecting resolution based on droplet size, coupling droplet size and position. This traditional method results in pixelation and discontinuity in small features, and limited control of edge definition and layer flatness. Therefore, we introduce “Off the Grid” (‘OtG’): new pattern design methods which decouple droplet size from droplet positioning, compatible with existing 3DIJP systems and applicable to 3D structure optimisation. We demonstrate: printing fine features one droplet wide with reductions in geometry error, forming smooth continuous paths where the traditional pattern methodology did not; up to 10× increase of feature position control (Traditional: 60 μm increments, minimum gap 45μm; OtG: 6 μm increments, minimum gap 5μm); adjustable print resolution across a patterned layer; 2.5× reduction in surface waviness and control of surface texturing.
8:40 AM
Designing for Cleanability: A Topology Optimization Approach for Electron Beam Melted Parts: Alptug Öztaskin1; Evren Yasa2; 1Addpark Advanced Engineering; 2AMRC North West University of Sheffield
Residual sintered powder is a fundamental problem in Electron Beam Melting (EBM). Although this problem is widely recognized by those who perform Design for Additive Manufacturing (DfAM), a commonly used AM design methodology, topology optimization processes often lack this constraint as either a penalty or criterion of acceptance. To address this issue, we model cleaning tools and/or media (e.g., sandblasting guns) as simple shapes formed of line segments. We measure the accessibility of the mesh surface using simple models based on a series of simplifying assumptions. We perform sampling on the mesh to reduce the number of operations, and we perform ray tracing with different elevation and azimuth angles with respect to the sample point normal. The accessibility of the points is normalized based on the intersections, and the normalized values are used in topology optimization as penalties as well as for validating final designs.
9:00 AM
Design Optimization, Multi-axis Additive Manufacturing, and Mechanical Evaluation of Continuous-fiber Composite Structures: Joseph Kubalak1; Kieran Beaumont1; Christopher Williams1; 1Virginia Tech
Multi-axis material extrusion (MEX) enables reorientation of the deposition tool relative to the part (via industrial robotics) such that every deposition can be aligned to arbitrary (e.g., 3D) load paths. In combination with continuous fiber-reinforced materials, this manufacturing capability can achieve unprecedented part performance. However, designing and manufacturing structures that exploit these capabilities is challenging. Here, we leverage both (1) a topology and toolpath optimization workflow that optimizes the distribution and orientation of a continuous fiber-reinforced composite for multi-axis MEX and (2) a novel deposition tool that enables printing and cutting of such materials. Optimization constraints (tailored for continuous fiber materials) are imposed to improve design printability and fiber length. Output designs are fabricated on a multi-axis deposition platform outfitted with a custom co-extrusion tool (capable of simultaneously metering continuous carbon fiber with a thermoplastic matrix). The resultant structures, featuring optimized layer-less toolpaths, are then mechanically evaluated.
9:20 AM
Design for Internal Lattice Structures with Application in Additive Manufacturing: Donald Palomino1; Ryan McClelland2; Mike Grau3; Ryan Watkins4; Bingbing Li1; 1California State University Northridge; 2NASA Goddard Space Flight Center; 3Autodesk Inc; 4NASA Jet Propulsion Laboratory
Internal lattice structures have the potential to significantly reduce the mass of an existing metal component, which is a desirable characteristic in the aerospace and automobile industries. However, there are still uncertainties on whether or not internal lattice structures can outperform a solid version of the same mass. Additionally, internal lattice structures can only be produced via additive manufacturing methods, bringing more challenges to resolve. To determine the viability of internal lattice structures, a study will be performed to compare its mechanical properties with solid, hollow, and mass penalty designs of equivalent masses using Autodesk Fusion 360. A performance baseline will be established by running multiple simulations on simple geometries to obtain the maximum displacement, first four modes, and first buckling mode. A generative design part, better known within NASA Goddard Space Flight Center as A15, will undergo the same simulations and have its results analyzed to determine feasibility.
9:40 AM Break
10:10 AM
Continuous Fiber Reinforced Composites: Design for Additive Manufacturing: Timothy Yap1; Ali Tamijani2; Mehran Tehrani3; 1University of Texas at Austin; 2Embry-Riddle Aeronautical University; 3University of California, San Diego
The design freedom enabled by additive manufacturing (AM) allows for intricate fiber steering and strategic placement, resulting in composite structures with enhanced stiffness and strength tailored to the specific needs of the structure. This presentation discusses both stiffness- and strength-based optimization of continuous fiber-reinforced composites produced using AM. To ensure successful printing, designs with optimized fiber path and geometry are converted into G-codes and post-processed to meet AM constraints, The parts are then subjected to experimental validation, comparing finite element analysis (FEA) results with digital image correlation (DIC) measurements. The findings demonstrate significant improvements in performance and weight reduction, highlighting the benefits of combining advanced optimization techniques with AM for composite materials.
10:30 AM
Discovery of Next-generation Battery Electrodes using Topology Optimisation: Chikwesiri Imediegwu1; Milo Shaffer1; Mary Ryan1; Ajit Panesar1; 1Imperial College London
Energy storage systems (ESSs) are essential components for the delivery of uninterrupted renewable energy of the future. A key stride towards the development of these systems revolves around the design of insertion-electrode battery chemistries such as Li-ion and Na-ion cells. These batteries lie at the heart of technological advances in battery design due to their high energy density and rate capabilities. However, conflicting cell requirements and the historical slurry cast technique for manufacturing electrodes serve as limitations to performance optimisation. This work presents a physics-informed strategy for the control of electrode nano-architecture towards optimising cell performance. This search for optimal electrode topology is gradient-driven, constrained only by the governing ion-transport and electrical conduction mechanisms within the cell material phases. Preliminary results are promising with physically optimized topologies derivable by additive manufacturing.
10:50 AM
A Case Study on Lightweight Design of a Robot Leg: Integrating Topology Optimization and Lattice Configuration: Shujie Tan1; Liping Ding1; Lei Yan1; Yicha Zhang2; Huaizhi Zong3; 1Nanjing University of Aeronautics and Aestronautics; 2UTBM; 3Zhejiang University
Additive manufacturing (AM) provides designers with increased flexibility to create highly complex and lightweight designs. Topology optimization (TO) and lattice configuration (LC) have emerged as the two primary strategies for achieving lightweight structures in the design for additive manufacturing (DfAM). However, both approaches exhibit certain limitations when redesigning intricate components, such as a robot leg. This paper integrates TO and LC technologies for lightweight design and proposes a novel hybrid lightweight design methodology. To illustrate the effectiveness of the proposed approach, a case study involving the lightweight design of a robot leg fabricated using the selective laser melting (SLM) process is presented. The results demonstrate that the hybrid lightweight design methodology outperforms the singular TO approach in terms of manufacturability and stress distribution.
11:10 AM Cancelled
Constrained Topology Optimization using Mechanical Homogenization: Ehsan Haghighat1; Clarissa Gutierrez1; Kyle Kloster1; Saigopal Nelaturi1; 1Carbon Inc.
Additive Manufacturing (AM) has transformed part design, making it possible to create intricate geometries that traditional manufacturing techniques cannot. Mechanical Homogenization (MH) offers a faster approach to explore the average mechanical characteristics of prescribed topologies. However, MH can have poor correspondence when scaled to complex parts. To overcome this limitation, we propose a homogenization-based topology-optimization (TO) approach to produce optimized topologies using MH while satisfying part-level constraints. Our MH model captures different deformation regimes, from linear elastic to plateau and densification regimes that are the result of buckling and self-contact of individual struts. Incorporating such constraints in classical TO approaches is nearly impossible. We demonstrate the effectiveness of our approach through an insole optimization problem. By incorporating homogenization into the TO process, we aim to make the design process more efficient and accessible to a wider range of users.