Shape Optimization

How to design parts that are stiff and light

Shape optimization is a powerful tool for finding a balance between two parameters.

Lets say you're designing a C-Clamp frame.

You want two main things:

• Maximize stiffness of assembly

• Minimize amount of material

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The less material you use, the cheaper is will be to make in mass production. 

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The question is, how do you get there?

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Fusion 360 offers a great tool for this! Best of all it takes like 30 seconds to set one of these up and then it's all solved in the cloud.

Step 1: Constrain some part of the model.

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This is the "fixed" part that cannot be moved. In the c-clamp case, it's the threads of the screw. This could also be the top clamping surface. It doesn't really make a huge difference. 

Step 2: Apply a force to the model.

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This is where all the force will be applied. This is the top clamping surface for the c-clamp. As mentioned above, this and the constrained part of the model are interchangeable for this c-clamp frame.

Step 3: Add keep-out zones and symmetry.

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Keep out zones make sure the simulation leaves material in certain areas. I've applied them to the top clamping surface and around the threads.

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I've also added a plane of symmetry down the middle of the part. This helps reduce the solution time. for the c-clamp, the result will be symmetric, so no point in taking longer to solve than necessary.

Step 4: Solution!

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Here is the solution for a mass target of 30% of the original.

Play with the Model

You can switch to the simulation view by hitting the button in the upper left corner:

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Controls:

• Left click and hold to orbit

• Right click and hold to pan

• Scroll wheel to zoom

Download Model

Bike Frame

Chair

Bridge

Cantilever Beam

Tips and Tricks

1. Material doesn't matter for shape optimization. This is a linear optimization

2. Unless you have multiple forces, magnitude of force doesn't matter either

3. Given points 1 and 2, it's important to redraw the optimized shape, and run a classic static FEA on it to make sure the shape is strong enough

4. Push the mesh density as high as you can. It makes a more accurate results. Low mesh densities will solve in the cloud in a few minutes, but are pretty rough. A maxed out mesh may take 4 hours to cloud solve, but the results are very good.

5. Always specify planes of symmetry, and any keep-out zones