Tutorial 10: Generative-Design Bracket

Goal#

Use generative design to produce a lightweight bracket that supports a 1,500 N load. The bracket joins a fixed mounting plate (four M8 bolts) to a 20 mm shaft bearing seat that carries a downward force and a side force. You will model only the interface geometry yourself, ask the solver for outcomes in three manufacturing methods and two materials, pick the best candidate, convert it to a usable body and validate it with a static stress study.

Generative design is a different way of working. You describe the problem (what must stay, what must stay empty, what loads act, how it will be made) and the software proposes shapes. The quality of your problem definition determines the quality of the outcomes. This tutorial emphasizes that setup.

What you'll learn#

• Preparing a design-space model: preserve bodies, obstacle bodies and optional starting shape.
• Applying structural constraints and multiple load cases.
• Choosing objectives, safety factors and manufacturing constraints.
• Understanding the cost of a study (cloud credits) and using Pre-Check.
• Exploring outcomes with filters and comparing them.
• Converting an outcome to editable geometry and validating it.
• Preparing the result for machining or printing.

Prerequisites#

• Tutorials 1 and 8 for modeling and manufacturing context.
• Familiarity with the Simulation section, especially Loads and Constraints and Static Stress.
• Understand licensing and cost: generative design needs a commercial subscription, trial, start-up or educational license (Personal use is not in Autodesk's list). Generating a study costs 11 tokens, or is unlimited with the Simulation Extension; setup, Pre-check and Previewer cost nothing. If you cannot generate, you can still follow the modeling and setup steps.

The problem statement#

Steps#

Part A: Prepare the model in the Design workspace#

1. New design Gen Bracket. Add parameters if you want: plate = 100 mm, plate_t = 12 mm, bolt_sq = 70 mm.
2. Plate body. New component Plate, sketch on XZ, Center Rectangle plate x plate, extrude plate_t as a New Body. Add four through holes with the Hole command, 9 mm diameter, From Sketch at the corners of a 70 mm square. (This tutorial assumes Z up, so the XZ plane is vertical and the plate thickness runs along Y.)
3. Seat body. New component Seat. Create an offset plane 90 mm in front of the plate face. Sketch a circle of 34 mm diameter centered 60 mm above (+Z) the plate center. Extrude 20 mm away from the plate (the seat then spans 90 to 110 mm from the plate face). Then cut the bore: circle of 20 mm through all. The seat is the surface that receives the loads.
4. Obstacle bodies. New component Obstacles. Make the following solid bodies:
   • Four cylinders, 18 mm diameter, 14 mm long, over each bolt hole on the bracket side of the plate, to keep room for bolt heads or nuts and washers.
   • A box 60 mm wide, 40 mm high, 120 mm long under the seat as a cable corridor. Make obstacle bodies visible but separate; give them a distinct color.
5. Starting shape (optional). To bound the problem, create a box covering the volume between plate and seat: 100 mm wide (X), 127 mm high (Z from the plate bottom edge at -50 mm to the seat top at +77 mm) and 110 mm deep (Y, from the plate face to the far end of the seat). Name it Envelope. It must touch every preserve body (the plate face and the seat). Set the obstacle bodies as Obstacle Geometry in the study; the Starting Shape is only the initial shape the solver may add to or remove from.
6. Save. Save the design. This is the last time you work in the Design workspace until after the study.

Part B: Create the study#

7. Switch workspace. Choose Generative Design from the workspace menu and name the study Bracket Study.
8. Design Space. On the Define tab, in the Design Space panel, click Preserve Geometry, and select the Plate and the Seat bodies. These are regions the result must retain. Next click Obstacle Geometry and select all obstacle bodies. Then click Starting Shape and select the Envelope body.
9. Hide non-involved bodies. Use the eye icons to confirm that only intended bodies appear in each role.

Part C: Constraints and loads#

10. Structural Constraints. Choose Design Conditions > Structural Constraints and use Fixed (the other types are Pin, Frictionless and Remote). Select the inner cylindrical surfaces of the four bolt holes; constraints and loads may only go on preserve geometry, and a load and a constraint cannot share a face.
11. Load Case 1. Structural Loads > Force. Select the inside cylindrical face of the bearing bore. Direction along -Z, magnitude 1,500 N. Name the load case Load Case 1 - Vertical.
12. Load Case 2. Create a second load case using the Load Case selector in the browser. Add a force of 800 N along -Z and 600 N along +X (or one vector with components). Name Load Case 2 - Combined.
13. Bearing load. Structural Loads also offers a Bearing load for cylindrical faces, which suits a shaft in a bore; a plain Force on the face is acceptable for this tutorial.
14. Self-weight. Gravity is negligible compared to the loads, so leave it off.

Part D: Objective and criteria#

15. Design Criteria. Choose Design Criteria > Objectives: select Minimize Mass and set the Safety Factor limit to 2.0. Optionally add a local Displacement limit of 0.25 mm on the bearing bore so the shaft alignment stays acceptable.
16. Manufacturing. Choose Manufacturing > Add. Create three methods:

• Unrestricted (additive or casting; no manufacturing limits).
• Additive with Overhang Angle 45 degrees (the default), Minimum Thickness 3 mm, Orientation Y+.
• 3-axis milling with Minimum Tool Diameter 6 mm, Tool Shoulder Length 40 mm and a tool direction along the plate normal (Y). Each method yields its own set of outcomes. Tokens are charged per study, not per method, but every method, direction and material adds outcomes and solve time, so keep a first run small.

17. Materials. Click Study Materials (1 to 7 per method) and add Aluminum 6061 and a titanium alloy from the library.
18. Pre-Check. Click Generate > Pre-check. Autodesk's setup requirements are at least one preserve body, one material, one constraint and one load on preserve geometry, and a starting shape that touches every preserve body; fix any reported issue (in the Design workspace if necessary). Optionally run the Previewer.

Part E: Generate#

19. Generate. Click Generate. A dialog shows the generation settings and cost (11 tokens per study unless you have the Simulation Extension); accept it. Solve time depends on the number of methods and materials.
20. While waiting. The study keeps running on Autodesk servers; you can close Fusion and come back. Follow progress in Generate Status.

Part F: Explore#

21. Open Explore. The Explore environment offers Thumbnail, Properties, Scatter Plot and Table views. Use the Scatter Plot with Mass on one axis and Safety Factor on the other, and use the outcome filters and Recommended outcomes.
22. Inspect. Click an outcome to see it in the view; switch among Stress, Displacement and Safety Factor. Check the thinnest sections: check the thinnest sections against the limits you set (3 mm for additive); for milling, ensure the tool can reach all surfaces.
23. Select candidates. Pick three: the lightest additive one, the lightest milled one, and a conservative one with SF above 3.
24. Compare. Use the Comparison View to look at them side by side.

Part G: Bring it back#

25. Create Design. With an outcome selected, choose Explore tab > Create > Design from Outcome (or Mesh Design from Outcome for a mesh body) and click Create design. This runs on the cloud: track it in Job Status and click Open Design when it finishes (you can create up to four at once).
26. Smooth and edit. The design from an outcome is a T-spline (Form) body that you can edit in the Form environment; use Finish Form to convert it to a B-rep. Verify details in the Form and Mesh sections of this guide.
27. Add interface features. Because the preserved bodies were included, bolt holes and the bearing seat should be exact; check the result. Add machining allowances, fillets (2 mm minimum) where outcomes show sharp junctions, and a clean chamfer on holes.

Part H: Validate#

28. Simulation. Switch to the Simulation workspace. Create a Static Stress study. Apply the same constraints and the two load cases, assign the same material, and generate a mesh (Mesh Settings with a global size of about 3 mm for the first run, refined near holes).
29. Results. Solve (local or cloud). Check the maximum von Mises stress against yield strength divided by the safety factor: read the yield strength of the material you assigned; the allowable is that value divided by the safety factor (for example, a 240 MPa yield gives 120 MPa at SF = 2). Check the displacement at the bore.
30. Iterate. If peak stress is too high near a sharp fillet, increase fillet radius and rerun. Mesh refinement near singularities such as sharp reentrant corners may show artificially high stress, so look at converged regions.

Checkpoints#

• Preserve bodies show as green in the setup; obstacles in red.
• Pre-Check shows no errors.
• The Explore tab lists outcomes for each method and material you selected.
• Validation shows a safety factor of 2 or more everywhere except possibly at stress singularities.

Variations#

1. Add a third load case such as an impact load of 3,000 N for one second as a static equivalent.
2. Frequency constraint. Check modal frequencies with the Modal Frequencies study and avoid resonance.
3. More methods. Add 2-axis cutting or 5-axis milling and compare the outcome sets.
4. Compare with Shape Optimization. Run the Shape Optimization study on a conventional bracket.
5. Topology printed in titanium with supports analysis.

Troubleshooting#

Related#

• Generative Design page covers each option in full.
• Loads and Constraints and Static Stress for the validation step.
• Cloud Solve and Credits for cost handling.
• Tutorial 8 for the machining half.