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Old 10th Sep 2013, 08:38
  #820 (permalink)  
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Thus, when any short or arc occurs close to CFRP, the skin temperature always peaks higher than the highly conductive aluminum alloys, thereby exacerbating any or all fires besides which, incurring permanent structural damage starting at around 375 degrees F and being flammable with a very low self ignition temperature of 580 degrees F
On the other hand, the thermal conduvtivity of molten aluminum is still about the same as for solid one, while the thermal conductivity of charred CFRP is far less, than the one of intact one. Therefore thick CFRP will protect itself from a localized heat source, while Aluminium will burn through locally. However, this means structural damage and requires a repair. It also means toxic fumes. But especially for thicker material, CFRP stands a local fire better than aluminum from a load carrying standpoint. For thin material both will fail anyway. A hot spot like a shorted wire or an arcing one may do more and more localized damage to CFRP than to aluminum, due to the localized heat which is better dissipated for metals. But when charred on the surface, this effect will quickly compensate the localized heating.
Also remember that for items mainly loaded in plane tension (e.g. a fuselage skin), burning of the resin does not keep the carbon fibres (good for > 2000 °C) from carrying tension loads. Molten Aluminum does not carry anything.
You simply can not compare apples and oranges. And I do not say CFRP is better!
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