Design advancements are exciting and offer solutions to complex problems that were previously unthought of. But we can’t forget the manufacturing processes needed to fabricate and eventually implement that new and optimized design. This article focuses on the emerging generative design technology in Fusion 360 and multiple ways to manufacture those designs, capitalizing on additive manufacturing, subtractive manufacturing, and a combination of both. The goal will be to explore design and manufacturing workflows to bring this emerging technology into the fold for potential users with varying levels of manufacturing capability.
Generative Design Overview
Generative design is an emerging design technology that, at its core, generates multiple outcomes to a design problem based on performance requirements, materials, and manufacturing strategies. You can generate and explore designs that meet your performance and manufacturing requirements while off-loading the computation to the cloud and freeing up your engineers—or yourself—to tackle other challenges.
Let’s take a closer look at the process and what it really takes to generate a design. Unfortunately, generative design isn’t quite magic yet, so there is a bit of front-end work to set up a generative study and start seeing some results.
Obstacles and Preserves
Obstacle and Preserve regions help define what geometry must and must not be in the final result. Every part has some kind of interface with another part, like bolt holes, tapped holes, rails, dovetails, etc. Preserve regions define these areas that must exist for the part to function properly.
Obstacle regions define areas that need to be avoided by the generated outcome. This might include other parts in an assembly, fasteners, tools, and the path of motion of other assembly components.
A Starting Shape is not required to run a generative design study. You may include a starting shape if desired, which will increase the surface area to volume ratio and can help shape the results. Starting Shapes must intersect with all Preserve regions, or the generative study will fail.
Load Cases
The load cases will determine where material is added to ensure that the design meets the performance requirements. Currently only linear static loads are accepted, but there are plans on the roadmap to add non-linear, dynamic, and thermal cases as well.
Currently, Structural Constraints include Fixed, Pinned, and Frictionless. Fixed Constraints can be set to the X, Y, and Z aces (rotation and translation). Pinned Constraints can be set to Radial, Axial, and Tangential. Currently Loads include Force, Moment, Pressure, and Bearing Load. Loads can be applied at vertices, edges, and faces as makes sense for the load type.
One important note: loads and constraints can only be applied to Preserves. Obstacles are just there to prevent material from generating in areas that cannot have material.
Generative design takes manufacturing method into consideration from the start to help ensure the result is something that can be made.
Manufacturing Constraints
Manufacturing is a consideration that’s often considered late in the design process or left as something for the manufacturing specialist to figure out after the fact. Generative design takes manufacturing method into consideration from the start to help ensure the result is something that can be made.
The three manufacturing options are currently Unrestricted, Additive, and Subtractive. Unrestricted doesn’t take manufacturing method into account and generates whatever geometry is determined necessary. Additive takes in the Maximum Overhang Angle and Minimum Thickness, adding material to meet the overhang angle. Subtractive can be defined as 3- or 5-axis. Both methods take in the Minimum Tool Diameter and Length, and 3-axis constraints also take in the setup directions.
Material Selection
Any material in the Fusion 360 library can be selected as a study material, as long as that material is linear, so unfortunately materials like wood are out for the time being. You can also define custom materials in the Physical Materials dialog to best simulate custom additive polymers or specific subtractive alloys.
Objectives
The Objectives are either Minimize Mass or Maximize Stiffness. Minimize Mass takes in a factor of safety target and generates as little material as possible while meeting that requirement. Maximize Stiffness takes in a factor of safety and mass target and tries to reduce deflection for the given mass target.
Exploring Results
Once you hit the Generate button, Fusion automatically opens the Explore environment where results will start to populate.
Exploration tools like detailed thumbnails, filters, and customizable scatter plots help you find the results that best match your design, engineering, and manufacturing requirements.
New Design and T-Splines Editing
Once you find a result that meets your requirements, create a new design using the Export button. This takes the result through a mesh to BRep conversion, creating a new Fusion design with the resulting solid body.
This translation process creates a T-Spline body that represents the organic surfaces created by generative, while maintaining the sharp edges and cylindrical faces from the original preserve geometry. The extremely powerful part of this conversion process is the ability to edit the results using T-Splines. Simply right-click on the T-Spline feature in the timeline and select Edit to open the Fusion 360 Sculpt workspace where there are extensive editing tools. If you’re new to T-Splines, don’t worry, there are plenty of online tutorials.
Simulation
If you’ve made significant changes to the result with T-Splines editing or if your load cases are better represented with a simulation study more advanced than linear static, you may want to take the edited result through Fusion 360’s Simulation Workspace. Fusion 360 uses Nastran solvers and offers advanced simulation study types including Modal Frequencies, Thermal Stress, Structural Buckling, Non- Linear Static Stress, and Event Simulation.
Manufacturing
Once you have a result that you’re ready to manufacture, Fusion 360 offers tools for additive and subtractive manufacturing in the Manufacturing Workspace. The additive tools are currently in preview and are limited to positioning the model on a representation of the build plate and generating support structures including Area with Polyline, Area with Volume, and Area with Bar. These supports are largely targeted at metal sintering but supports for plastic are on the roadmap.
The subtractive manufacturing tools include mature 2- and 3-axis milling, with easy conversion to positional multi-axis (or 3+2 programming) and offer some basic simultaneous multi-axis programming. Turning, mill-turn, and profiling operations are also supported.
Check out all the related classes available on the AU website on topics like manufacturing strategies, CAM in Fusion 360, the fundamentals of milling, and more. And this ADSK News article details how Autodesk is upping the ante on advanced manufacturing technologies.
Steven Szymeczek received his bachelor’s degree in mechanical engineering from Northern Arizona University. Steven worked in the aerospace industry for several years as a design engineer while growing his product development skills and interests on the side, eventually starting Penumbra Engineering in 2014 with friend and fellow engineer Dean Pierce. Currently, Steven is co-owner of Penumbra Engineering, located in Tucson, AZ. Penumbra focuses on empowering companies to use the advantages of additive manufacturing.
Matt Lemay is a part of Autodesk’s Fusion Adoption team, focused on ensuring customer success in the adoption of generative design and additive manufacturing. Before joining Autodesk, Matt was an applications engineer in the Aerospace Composites industry and a design engineer for additively manufactured surgical implant technology.
Marti Deans graduated from University of California, Berkeley where she earned her bachelor’s degree in mechanical engineering and explored manual and CNC manufacturing processes in the Berkeley Student Machine Shop using MasterCAM, HSMWorks, and InventorHSM. With this experience, she joined Autodesk, first developing training and adoption strategies for Fusion 360 users with a focus in manufacturing and now driving awareness for Fusion 360 and its manufacturing capabilities.