Carbon Fiber Tubs

[fsae_alum]

To those either doing or those who have done carbon fiber tubs, how did you go about making them in one piece? I know that in the past in F1, they made a bottom half and an upper half and then bonded the 2 pieces together. I undestand that now they are doing the entire tub at once as one big piece!!! Has anybody here done that and if so, exactly how? Plug assist, etc...?

Thanks!!

In spite of...

[fsae_alum]

To those either doing or those who have done carbon fiber tubs, how did you go about making them in one piece? I know that in the past in F1, they made a bottom half and an upper half and then bonded the 2 pieces together. I undestand that now they are doing the entire tub at once as one big piece!!! Has anybody here done that and if so, exactly how? Plug assist, etc...?

Thanks!!

In spite of...

[Ryan Parker]

hey fsae alum,

there seems to be two ways that are being done at the time, prepreg rolling and filament winding, read more in the composite half shafts forum to catch up on what composite work is happening.

parker
virginia tech formula sae

[Fox]

We at Delft University did our first tub in two pieces (left and right instead of top bottom split) The second and third tubs where one piece products. The biggest problem for us was letting the fabric stick to the "ceiling" of the mould. The rest is quiet simple. The sticking problem can be resolved by using spray glue (dry fabric) or heat blower (pre-preg).

[Erik C]

Fox, first, what material did you make your tools from? Carbon or Glass. Second, in areas where you have core have you ever encountered problems getting both face sheets to cure at the same time, i.e. the tool side cures after the bag side. I don't know how relevant this is ,as your lay-ups were probably not very thick. Just thought I would ask.

[Fox]

Plug was made out of wood (MDF) and lots of plaster...Mould was extracted from that in two fibre-glass (short fibres) halves.
For manufacturing the final product we used the vacuum assisted resin transfer technique. At the drivers sides we used some foam core material to create a sandwich. This foam is perforated to make sure the resin gets on both sides AND you have direct links between both layers. So after injecting the resin hopefully the resin is everywhere. After that you let it cure at room temperature for about 24 hours (with the epoxy we used) After that we post cured it in a big oven. Conclusion; I do not realy get your point (/problem) with what your saying about delayed curing at the bag side. Is it a problem and where the hell does it come from???? Do you use heatblowers to heat the outside for curing? This would in the beginning result in a warmer (read: faster curing) out/tool-side.
And one more comment on lay-up. At a lot places we use four layers (total thikness of 1 mm) wich proves to be sufficient. Youre not building a tank nor a F1 tub!

[Erik C]

I was speaking more about an elevated temp cure (i.e. in an oven), not a room temp. The problem arises from a having tools which don't heat up as quickly as the interior face sheets. So air gets trapped between them causing some issues with delamination. But like I said, with only 4 layers of carbon, using an rtm technique at room temp, then you would not have come across this problem.