Although I'm no expert in CF I had some courses on Materials Engineering and one of the few pieces of information that I kept regarding CF is that the process that was used to strengthen and stabilize the CF required a stage in a autoclave to subject the piece to high pressures and high temperatures in order achieve a evenly distribution and a proper cure of the resins. Only this process could provide the strength to the part and the present the part with the distinctive carbon fiver weave.

In this process documented in the photos it seems that the work done was by the "wet" process, that is more of a patching solution, and certainly not suited for a part that is so solicited as a tub on a Carrera GT.

So it's understandable the reluctance to applaud this intervention without further informations on the used methods.

 

^^ I don't think I posted the picture of it, but they built an oven around the door sill and baked the CF.

 

that's pretty cool!

 

JENGA!!!













I couldn't help myself.

 

Thats not plausible because a autoclave couldn't be built around a door. It needs a great level of isolation because of the high negative pressures that he should be able to achieve in some stages of the process.

What you see in the pictures is just a bag that is put around the carbon fiber to create negative pressures in other to distribute and cure the resin, but in no way it is possible to compare this process to the autoclave process.

This method of creating vacuum in the bag and using CF in rolls is suited for non-structural pieces and it's used by many small companies in the auto business to produce parts such as air-intakes, mirrors... because they don't need the structural strength that a tub needs. Probably that facility is used to build kayaks because thats a method used by some companies in that area...

Producing a complex CF part that is engineered to be highly solicited by all kind of forces, such as a tub, requires several stages of cure in very controlled conditions of pressure and temperature.

It's not possible to achieve with this repair the same structural integrity of the original tub, and that rebuild area is going to, probably, cause forces in the tub to be distributed in a different way, creating points of higher concentration of stress.

In conclusion, from what I can see this repair it's not on the same level of the original car.

 

I'm sure you know way better than I do, but here's the image I was reffering to with the oven.



And the guys who repaired it said the durability of the repair wasn't the problem, as the Carrera GT's structure is so strong that even without the repair it would have driven fine. But once again, I don't really have a clue about Carbon Fiber. I just know that its light, strong, and looks cool.

 

^ ^ ^
Agree with FRM
Were my thoughts as well.
CF to attain maximum strength requires autoclaving to best of my knowledge.
A heat cure alone won't cut it.
The guy will be driving an accident waiting to happen.

 

As I said, damage to the tub wasn't really that significant (the structure was fine), it just looked terrible visually.

 

Carrera, why you post a link to the proper thread on f-chat or rennlist (I can't remember which) so they can see it was a proper repair and not the hack job your thread makes it to be.

 

From my FSAE days. An autoclave is only a requirement for prepreg carbon. This is because of the epoxy already embedded in the material. Additionally prepreg must be stored at 0*C due to the epoxy. A wet layup will be just as strong as a prepreg/dry if the epoxy to material ratio is correct. Vacuum bagging helps achieve this by evenly distributing epoxy and removing excess into bleeder cloth.

I would have concern with how load is transferred through the patch. It looks like they wrapped a larger piece over the hole area which would create a decent load path...I think.

Very cool that they are repairing the car. It would be interesting to learn if Porsche would handle it any different. Thanks for posting Carrera. If you find anymore info post it up.