Vacuum Infusion for a Seat

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#1

Hi all, I am attempting to make a seat using a vacuum infusion method. The application for the seat is SAE mini baja-Im not sure if any of you are familiar with the competition, but basically it is a collegiate engineering competition.

Im not to concerned from the mold side but rather the layup and process aspect, as I have no personal experience with the material, and neither does my team, so I am trying to come up with a quality part on the first try with little experience, a very tall order I know.

We will be using a male mold, if that effects anything.

This is our materials list, along with a preliminary layup.

3x100gsm spread tow
dyvinmat core
3x100gsm spread tow

We are going to use US composites’ 635 thin resin.

The other materials will be:
PeelPly from US composites
Flow mesh from Fibreglast
Strechlyon Vacuum Bagging
Fibreglast Spiral Tubing.

My questions are:

  1. Am I missing anything in terms of layer or materials?
  2. Are any of the products I have chosen known to be bad, or are there better choices?
  3. Does this lay up look strong enough for a seat, if not how many layers of carbon fiber would result in a satisfactory part?

Cheers, and thanks for your help!

#2

that resin is too thick imo and the longest working time is too short. You will want to mix ~2-3min, degass ~10-15min (prob longer given the thicker viscosity) and then you will have to infuse. Given the size of the seat and the thickness of this resin you will want to raise the temp of the resin to thin it but this will drastically cut your working time and it will prob gel with minimal infusion…

#3

Are there any suggestions for resins that are readily available?, The companies I saw in the thread of infusion resins were either EU or AUS/NZ based…

#4

… ya welcome to USA/Canada… I’m not sure where to get some of those, still looking for myself as well. Rhino linings might suit your needs, check them out.

#5

I tend to agree. You do a test sample first by laying up strips of your laminate schedule mirroring what you’ve planned for the seat on a glass top and bag it. (Same length as the nax seat span),But even then you’ll need to preheat that table and laminate stack with that resins vis.
It still may B stage too quickly though. Ask your vendor if he agrees ?

#6

I am currently looking for another resin due to concerns raised by 20_rc51_00, the way I see it, the more I plan the better it should turn out.

It also helps that I have not bought anything yet, so I can be fairly flexible with materials at this point. ( the carbon was already here so, i’ll take it)

#7

spread tow and uni’s need very low viscosity to properly infuse. Look in to Gurit’s Prime 20ULV, its ~150cps and has plenty of working time

#8

Ditch the stretchlon, and get some other bag. (WL5400, WL7400, RELBAG, Big Blue).

Also do not forget a sealant tape, tubing, etc.

#9

Ok, thanks for your help, I had no idea that specific resins existed for this application.

#10

If the design/cost portion of Baja is similar to Formula SAE you should be able to explain and justify the materials and layup that you choose.

I would start by looking at the loads you expect this seat to see, say a 150lb driver subjected to a 6g acceleration. After you have the loads and since you probably know the shape of the seat and sizes of the unsupported areas you can use classical laminate theory to figure out the ideal laminate. If you don’t have mechanical data I would just use approximate values from the internet or contact the manufacturer of the spread tow carbon.

#11

Thanks for the advice, is there any method for accounting for the presence of core material? without getting into sandwich theory?

#12

If you rotate some of the layers of woven carbon so your carbon skins have relatively the same properties (quasi-isotropic) in all the in-plane directions you can use beam equations for beams made from multiple materials (composite beams) but this will keep you away from classical laminate theory.

#13

Thank you.

#14

Well, now comes the time for the layup, I will be using mold release wax, PVA, 3x 100gsm Oxeon Spread Tow,divyncell (0.125), 3 more layers of carbon fabric, peel ply,an enka filter jacket, and then vacuum bagging. The resin is rhino linings 1411 system, which, if I am reading it right, has a viscosity of 45 cps.

I am wondering if some more flow material should be added before the vacuum bag,I have some enka flow media that I got just in case. Also, what is the most reliable spray adhesive for getting materials to conform correctly?

Cheers,
Kishen

#15

I cannot find a datasheet on the 1411 epoxy. Do you have it?

#16

http://www.rhinoliningsepoxy.com/gfGy6S44anlz/12615997431401-21%20dSheet_5513.pdf
I think that is the system if not, it is the only infusion resin on the web site (the labeling on the bottle list it as infusion). The material was donated to my team by rhino linings, and that is what they recommended.

#17

OK, 1401. Viscosity not 45 cps but 250 or so. That eases me out. I was afraid that at 45 cps you were given a diluted EP primer or concrete impregnation material, but it seems you have been supplied the good stuff. Go for it!