Originally Posted by amicus
Some typical thermal conductivity values for metallics are: (all units are in the widely accepted and used W/m/K):
Aluminum and its various alloys = 167
Brass = 116
Copper = 339
Steel = 48
And for CFRP it is 0.13, HA!
Yes, CFRP seems to be a pretty good insulator seems to be your point, and will not wick heat away into the adjacent structure, thus the local structural temperature can reach higher temperatures near a thermal event.
What you have omitted to show is information on how rapidly the other side of the structure heats. Heating one side of the skin does not create near-equal temperatures on the other side of a CFRP skin.
I do not think we will ever find molten CFRP flowing back in the airstream in a fire the way we see aluminum flowing during structural fires. It is going to sit there and char and continue to insulate until it is finally burnt through to the other side. If it also has structural loads on it, then it will eventually fail as it degrades and loses strength. In the case of aircraft skin in flight, it may hang on quite a while if the surface can dump enough heat to the local airflow since the layer of char formed near the fire will act as an insulator.
One of the key material issues in a fire is whether or not it will spread a fire. If it self-extinguishes away from the source of heat, then that is what is desired, and I would expect that it could not be certified if it did not self-extinguish.
Fume generation from hot CFRP is an issue, but that should be an engineering challenge that can be solved without making the cabin into a gas chamber.
It is just a different material with different properties. We have to learn what is different about it and adapt our thinking and engineering concepts.