Gas Tank Support

General Composites Discussions Composites Talk
#1

I need to make a composite fuel tank support tray for a street car. I believe there are also two steel straps that wrap around the fuel tank and underneath this tray support part.

Full fuel tank weighs 175lbs. I’m not making a new fuel tank, just the tray. So all you engineering types if you could help me determine how thick the fiberglass needs to be for this application? The bottom tank dimensions are approximately 38" wide x 21" and it is not a flat bottom there is one angle of about 15% and the tank tray support has curved outer edges that hug the bottom of the tank and extend up about 2" around the perimeter of the tank.

I will probably be using just one layer of carbon fiber twill 12oz and the rest of the cloth will be fiberglass. I’ll be using epoxy resin.

So, if you guys could help me out with how thick this new part should be - that would be awesome :slight_smile:

#2

Disclaimer: This is purely constructive criticism, and not meant to be “mean.” Just the truth.

It’s not as simple as just giving you a recommended thickness. This is why there are engineers and designers!
By just using 1 ply of carbon fiber, it already demonstrates a lack of general composite design knowledge. The laminate needs to be balanced.

Resin type matters. Core or no core? Nearby exhaust components? Any shapes built in can greatly enhance stiffness, but not necessarily strength. Etc…

#3

AS TET explained there are many factors that go in to designinig the proper laminate. My recommendation is to make several test panels and test parts and come up with some methods of truly testing there max loads under different circumstances. This will help you determine what is best for your application and will help you with future product design. Manufacturer flaws such as bad core or laminate bonds, high air and resin content will also be very important to be aware of.

#4

i’d suggest going for vacuum bagging and using core (coremat at least)… i would also suggest adding extra reinforcement to the mounting points, even using metal rings in the laminate in areas where bolts will be passing through.

just for the sake of it, i would make it with at least 5 layers of 300grm woven glass , and with 2-3mm core in it.