## 4 Fusion 360 Generative Design
### Fusion 360 GD Setup  
**Preserve Geometry:** Users must first select the geometry that they have identified as essential to the part. These bodies are 'preserved' and will remain in their entirety through the generation process. Often, these are bodies intended to interface with other components/ surfaces during use. Preserve geometry is shown in green in the Fusion 360 GUI. **Starting Geometry:** Designers can optionally select a starting body for generation. This informs the solver of an approximate shape, rather than enabling it to generate freely. Any starting geometry is shown in yellow in the Fusion 360 GUI. **Obstacle Geometry:** Obstacle geometry allows designers to partition regions of the design space where material is undesirable. Typically, this is used to prevent the generated outcome from forming in a way that would cause collisions with other components or surfaces. Designers are also provided with the option for the solver to avoid placing material within a user-defined offset distance from obstacles. Obstacle geometry is shown in red in the Fusion 360 GUI. **Symmetries:** Fusion 360 designers can constrain generation to be symmetric about selected planes. Since the GD solver is stochastic, symmetry is not otherwise guaranteed, even if the setup is symmetrical. **Structural Constraints:** These are required to ensure that the model converges. Designers are given the option to constrain any face, edge, or vertex by fixing or pinning normal to the surface or to a remote location. These constraints can each be selected for all DOFs, for example, X, Y, and Z in the case of a fixing constraint. **Structural Loading:** The application of structural loads enables the solver to perform the necessary FEA at each iteration of the generation. Without defining these loads, the solver has no measure of the generated geometry's performance. Fusion 360 provides multiple load types, which can all be targeted at any face, edge, or vertex: force, pressure,  
Figure 4: (**A**) Component constraints and applied load (red arrow). (**B**) The 100 \(\times\) 100 VESA interface for the applied load and constraints was to be fixed by four M6 bolts and nuts. (**C**) Testing setup using a custom jig mounted on the MTS Criterion Electromechanical Load Systems, C42.503, for recording load-bearing capabilities. moment, bearing load, remote force, and remote moment. The user can then select the magnitude and direction of the selected loads. **Material:** It is necessary to select the part material so that the solver can meet the mass or stiffness targets. Without the specific material property information, the objective function would not be calculable (when using the maximise stiffness objective the only accurate material data that is necessary is the density, as material is added and subtracted only under the assumption that more material adds stiffness until the mass target is reached). **Objectives and Limits:** At the time of writing, designers can choose between two principal objectives for Fusion 360's GD solver: minimize mass and maximize stiffness. When choosing to minimize mass, the solver iteratively removes material from the geometry until the part yields under the applied load, accounting for a user-defined safety factor (default = 2.00). When maximizing stiffness, the solver aims to do so whilst accounting for the user-defined safety factor, using material up to the user-defined mass target. Three optional additional objectives can be chosen alongside either of the required objectives explained above. Designers have the option to:  
* Tune the part to a user-defined minimum first mode frequency;
* Specify a desired part displacement when under load. This can be defined locally to a face, edge, or vertex or globally, in the X, Y, and Z directions;
* Add a buckling-stopping condition on top of the normal yield condition with a user-defined safety factor. **Manufacturing method(s):** Fusion 360 allows the designer to choose from multiple manufacturing methods, with the requirement that at least one is selected.