Initial Approach to Rear Wing Mounting

There are 3 primary approaches to mounting the rear wing that are commonly seen in the FSAE world, direct mounting, unsprung mounting, and swanneck mounting. Direct mounting is just mounting directly to the wing from the underside, and this is the easiest approach to mounting but it heavily disrupts the airflow on the underside of the wing, drastically impacting downforce. Then there is unsprung mounting, which involves mounting to the suspension of the car, keeping the wing in the same relative position to the ground at all times, and this is the best type of mounting from an aerodynamic perspective, but it takes the most time to implement and is very complex. Last but not least, there are swanneck mounts. These mounts connect to the top of the wing and keep the airflow on the underside of the wing relatively undisturbed, which means aerodynamic performance is mostly preserved. For our purposes, we chose to go with the swanneck mounting style as it is relatively easy to implement and offers good aerodynamic performance.

Free Body Diagram - Rear Wing

Topology Optimization Study - Rear Wing

Topology study using the forces described above in the free body diagram.

Final Rear Wing Mount Design

Rear Wing Assembly FEA

Once the design of the rear wing mount was complete, I wanted to validate the mounts with more than just single body FEAs, and did so by setting up an assembly level FEA of the full rear wing mounting system. I set the wing surface and the endplates to be completely rigid so that all the load placed on them gets transferred into the ribs, and from there into the mounts, an assumption that will hold to be relatively true in the real world and also make the simulation slightly less processing heavy on my computer. From the results, I found our mounting system to be extremely rigid, with our minimum factor of safety coming in at 3.7, and thus determined that no further changes were required.

Initial Approach to Front Wing Mounting

For the front wing, there is a slightly different approach, though it remains largely the same as the rear wing. To start, with the front wing, mounting from the underside is not even an option because of ground clearance, so all mounting will happen on top. Then, when considering how forces act on the front wing, it is important to note that the center of pressure is very close to the chassis, which means a very large moment will not be generated, thus, mounting can be smaller and shorter. This also brings in another new point, this mount would not have any rotational joint like the rear, where a supporting set of carbon rods take the downforce, and so, this mount will have to be designed to have 2 holes fixed, and 2 holes taking a load.

Free Body Diagram - Front Wing

Topology Optimization Study - Front Wing

Final Front Wing Mount Design

Here is the final front wing mount design! I added extra mounting holes along the vertical axis on the chassis end of the mount as well, allowing us to adjust the height of the front wing, generating more or less downforce from ground effect when needed.

Front Wing Assembly FEA

I also wanted to run an assembly level FEA for the front wing, as this mount was the only part connecting the chassis to the wing, unlike the rear wing which has the carbon rods on the underside as well, so it was crucial to further verify this design with whatever simulation capabilities we had available. Here I only set the wing surface to be rigid so that it can transfer load to the ribs and mount directly, and then set up my loading cases, including a lateral force on the edge of the wing surface, to determine whether or not a lateral stiffener like the rear was required. From the results, I determined that a lateral stiffener was not required and our minimum factor of safety came out to be 2.2.