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
​
The less material you use, the cheaper is will be to make in mass production.
​
The question is, how do you get there?
​
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.
​
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.
​
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.
​
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.
​
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!
​
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:
​
Controls:
-
Left click and hold to orbit
-
Right click and hold to pan
-
Scroll wheel to zoom

Bike Frame


Chair


Bridge


Cantilever Beam


Tips and Tricks
-
Material doesn't matter for shape optimization. This is a linear optimization
-
Unless you have multiple forces, magnitude of force doesn't matter either
-
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
-
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.
-
Always specify planes of symmetry, and any keep-out zones