Demolding and Reinforcements

Demolding

The method that was most effective in demolding the bottom panel was a super long compressed air nozzle. It allowed compressed air to push deeper into the panel which eventually caused the panel to essentially float off the mold. Shoutout to Brian and Graeme for the help.

Result and Assessment

The panel could stand on its own. However, the areas colored below was slightly weak and prone to vibrations

Weak Points and Consequent Reinforcements

Weak points are indicated with colored regions.

Blue was slightly concerning - if the midline was pressed down, the panel would deflect downwards significantly.

Red, the trunk, needs to be a bit stiffer as it will be used both as storage and as leverage to access things further into the car.

Green is concerning as it is very susceptible to lateral movement. Especially with this area being the “leading edge” of the bottom panel, it needs to be stiffer to maintain the aerodynamic integrity of the panel.

Reinforcement composition

The reinforcements consisted of using adhesive film to adhere core to the existing panel and then continuing the layup as planned. Layers, bottom-up, are as follow

adhesive film, this needed to be adhered on a surface that was sanded beforehand to allow for mechanical bonding
core - Nomex was used as it was flexible and didn’t require additional supplier interfacing. Foam core was also briefly considered as it's more conducive to wet layups (which were also initially considered) and has a greater bonding surface area.
Three layers of carbon fiber, with the middle layer having a 45 degree offset. Much of the layers were puzzled together with various smaller pieces. In an ideal world, this wouldn’t be done as it compromises some strength. However, given our timeline (4 days to complete the project, start to finish), we had to work with what was available in the bay.

First three layers were replicated. Our fabric was also woven instead of unidirectional (shown in the picture above). Having diagonal layers allows the layup to sustain greater loads that are not directly in line with 0/90 degree loads.

More info can be found here: https://dragonplate.com/quasi-isotropic-carbon-fiber-sheets

Final Reinforcement Areas

note: all Nomex was 0.5in, apart from a 75cm section of the red section that was 1in. The remainder of the red portion was 0.5in thick. This varying thickness allowed the bottom panel to be more easily integrated with the chassis.

note 2: blue section serves to raise the thickness of the panel and does not significantly affect the structural integrity of the panel. Raising the thickness allows for greater surface area for aero-chassis bonding.

RESULTS

Turned out better than I expected, may need to trim some of the side to make way to LCA