Generative Design Workspace

Overview#

Generative Design is a separate workspace in which you describe a design problem (where the part connects, what loads act on it, which space it may occupy, what it must avoid, how it will be made) and Fusion's cloud solver produces multiple design alternatives, called outcomes. Autodesk describes it as a multi-objective design exploration tool that provides multiple editable design solutions from a single cloud solve. You then explore the outcomes, create a design from the best, and validate it.

Compared with Shape Optimization (a simulation study on one target body that returns one mesh), generative design has its own workspace, design space geometry types, several manufacturing methods, multiple materials and many outcomes. Outcomes are a starting point for engineering, not a finished part.

Access and cost (Autodesk help):

• To use the Generative Design workspace you must have a commercial Fusion subscription, an active Fusion trial, a current start-up license or a valid educational license. A Personal-use licence is not in that list.
• Generating outcomes uses the Fusion Simulation Extension (unlimited studies) or tokens each time you generate a study. Autodesk's "Tokens for generative studies" topic gives the charge as 11 tokens for a generative study; the system consumes tokens when at least one iteration of any outcome is generated. The capabilities previously offered by the Generative Design Extension are now part of the Simulation Extension, so it is no longer a separate product.
• Setup, Pre-check and Previewer are not generation, so they do not consume the 11 tokens. A failed study (no outcome iteration) is refunded.

This page covers setup; running studies, exploring outcomes and validation are on the Generative Design Studies and Results page.

Where to find it#

• Workspace menu > Generative Design. The Define tab has these panels: Study, Edit Model, Design Space, Design Conditions, Design Criteria, Materials, Generate, Explore, plus Inspect and Select.
• Design Space panel: Preserve Geometry, Obstacle Geometry, Starting Shape, Symmetry Plane, Obstacle Offset.
• Design Conditions panel: Structural Constraints, Structural Loads (plus gravity, linear and angular global loads, point mass, and load case attributes).
• Design Criteria panel: Objectives and Manufacturing.
• Materials panel: Study Materials. Generate panel: Pre-check, Previewer, Generate, Generate Status/details.
• The browser holds the study, load cases, Objectives and a Manufacturing node with each method's Materials.
• Job Status (Application bar > Job Status icon > View Job Status) shows generative jobs in its Generative Designs tab.

Step by step#

1. Prepare the model in Design. Model the parts the new component connects to as bodies you can use as preserve or obstacle geometry.
2. Switch to Generative Design. Optionally use Edit Model to create preserve, obstacle and starting shape bodies (there are tools for bolt hole and pin hole preserve and obstacle geometry and a Connector Obstacle tool).
3. Create the study and open Study Settings if needed: Outcomes resolution (Low gives less detail but faster generation, High gives more detail and may take longer) and Remove rigid body modes.
4. Assign geometry types in the Design Space panel. Bodies with no geometry type are ignored.
5. Apply Structural Constraints to preserve geometry, then Structural Loads to preserve geometry. A load and a constraint cannot share a face, edge or vertex.
6. Set Objectives and limits (Design Criteria > Objectives) and Manufacturing methods.
7. Select Study Materials (1 to 7 per manufacturing method).
8. Run Pre-check, optionally Previewer, then Generate.

Setup requirements (Autodesk): at least one preserve geometry body, at least one material, at least one constraint on preserve geometry, at least one load on preserve geometry, and, if a starting shape is used, it must be in contact with all preserve geometry bodies. Pre-check shows red (cannot generate), yellow (potential issues, can generate) or green.

Options reference#

Design space:

Structural constraints (preserve geometry only): Fixed (default all three global directions), Pin (cylindrical surfaces only; radial, axial, tangential), Frictionless (normal to the surface) and Remote constraint.

Structural loads: Force (faces, edges, vertices), Pressure (faces, normal and uniform), Moment, Bearing load (cylindrical face), Remote force and Remote moment. A negative value reverses direction. Each use case is a load case (default load case in the browser; clone or create more by right-clicking). A load case includes gravity (self-weight from the study materials), loads and constraints. Equal and opposite loads in the same load case can cancel and are then not considered; put them in separate load cases.

Objectives and limits:

The solver tries to achieve the limits, but sometimes it may not be possible. Autodesk's example: Minimize Mass with a Safety Factor limit of 2 ensures the minimum factor of safety is equal to or greater than 2.

Manufacturing methods (each selected method produces its own outcome set; add Unrestricted to see the cost of constraints):

Materials: choose 1 to 7 per method, either for all methods or per method; each active method needs at least one. Yield strength gives the safety factor, Young's modulus and Poisson's ratio solve the linear stress problem, and density (nonzero) gives mass and makes gravity act.

Tips and pitfalls#

Tip: Use Previewer before generating. It shows a trend of where material goes using only general settings (Unrestricted method, one material, active load cases only) and becomes out of date whenever settings change. Autodesk says it helps reduce the time and number of generative jobs.

Tip: Apply a load or constraint to every preserve geometry body (Autodesk recommends it), and use realistic load magnitudes. Autodesk's example of a 1 N load on one preserve body and 10,000 N on another can make the solver exclude the smaller load.

Warning: If preserve bodies differ greatly in size, or carry small loads compared to the model, outcomes may separate into regions. Autodesk suggests increasing load magnitudes or reducing the size difference, adjusting Outcomes Resolution, or using a starting shape.

Warning: If you define only the obstacle that lets a bolt sit in place, material may cover over the bolt. Define the hole and the free movement of the bolt as obstacle geometry.

Tip: Choose manufacturing methods at the start. Each selected method (and each direction or orientation) multiplies the outcomes.

Warning: Outcomes are checked in Fusion by their own solver; Autodesk says you need to validate outcomes by creating and solving a Static Stress study from the generative setup.

Tip: Autodesk's help lists real-life load magnitudes: pint of water 5 N, large watermelon 50 N, standing human 1000 N, grand piano 5000 N, small car 10000 N; human grip 225 to 500 N. Use them only as rough starting points and consult experts for accurate loads.

Practice exercise#

Set up (but do not generate) a wall-mount bracket. In Design model a base plate with two bolt holes, a 20 mm shaft stub 80 mm away and a clearance cylinder around the mating part. In Generative Design: assign Preserve Geometry to the plate bolt bosses and shaft stub, Obstacle Geometry to the clearance cylinder, fix the bolt faces, apply a 300 N Bearing load on the shaft (an arbitrary exercise value), set Minimize Mass with a Safety Factor limit of 2, Manufacturing Unrestricted and 2.5-axis milling, and one aluminium material. Run Pre-check, then Previewer. Expected result: a green Pre-check and a preview showing material along the load path. Open the Generate dialog, select Token costs & balances and read the Required value without confirming.

Setting up the design space well#

Autodesk's guidance, in short: preserve geometry should be the minimum geometry you need in the final shape, including connections such as bolt holes and parts you interact with such as handles. Obstacle geometry keeps material out of neighbouring objects, represents range of motion (for example pedals or a turning wheel on a bike frame) and keeps holes free at connection points. A starting shape is optional; use it to optimize an existing design, and note that if you use one it is the initial shape, otherwise the initial shape is based on the preserve geometry. Large obstacles can split the initial shape into parts, which a starting shape may prevent.

General modelling advice (not Autodesk data): make preserve bodies thick enough to carry the loads and leave allowance for machining, and add an obstacle offset where you need extra clearance.

Load cases: modelling real use#

A part usually sees several loads, and each use case is a load case that the outcomes must satisfy. Typical cases to consider (examples, not Autodesk defaults): the main operating load, an overload or misuse load, a sideways load, a torque, and self-weight (gravity is included in each load case from the material density). Adding cases generally increases mass, so test them one at a time to see which drives the shape. Remove rigid body modes (Study Settings) is only for studies where no constraints are applied or where loads are balanced; it is not meant to replace constraints.

Pre-check and the cost of checking#

Pre-check and Previewer are free; the cost occurs when you generate. In the Generate dialog, select Token costs & balances from the Show list to see Required, Available and Will Remain; if Required exceeds Available, select another account or reduce the number of studies. You can generate several studies at once and track them in Job Status; you can close Fusion and see outcomes in Explore when you return.

Failure modes and fixes in setup#

Practice exercise#

Prepare a study and verify it without paying for a full run.

1. Model the base plate (illustrative 100 x 60 x 10 mm, two 6.4 mm holes), a 20 mm shaft stub, and an obstacle cylinder around the mating part.
2. Create preserve bodies for the plate bolt bosses and the stub.
3. Define three load cases (for example 300 N down, 900 N down, 100 N sideways on the stub; the values are exercise assumptions).
4. Run Pre-check and resolve each warning, then generate a preview.
5. Open the Generate dialog, read the Required tokens for the study and compare with the 11 tokens quoted by Autodesk, without confirming.

Related#

• Shape Optimization
• Loads and Constraints
• Cloud Solve and Credits
• Results Interpretation