FIRE PROTECTED CARBON FIBRE REINFORCED PLASTICS FOR STRUCTURAL AIRCRAFT COMPONENTS

Kurzfassung

The presented study deals with the optimization of fire properties of CFRP fuselage materials in a "pool-fire" scenario (a kerosene fire underneath an aircraft on ground) with the aim to increase the time until the structure fails. For this purpose hybrid material systems are being developed where the flame retardant is directly incorporated into the material. In this way, weight can be saved and the peeling effect, which is common for finishes, would be prevented. Due to the very high heat flux during a kerosene fire, powdered additives and layers are introduced into the composite, which form a thermal barrier or a barrier for gases in case of fire and protect the underlying structure from the effects of the flames. Of these materials, the fire behaviour with regard to smoke density and smoke toxicity is determined. The results show a significant reduction of smoke density for most of the tested materials and comply with the limits of toxic gases for cabin material systems. For a realistic relevelling of the “pool-fire” scenario, a test facility with a propane torch was build, which creates a heat flux of 180kW/m². In this test, the specimens are exposed to flames for 4min and the temperature profile at their backside is recorded with a thermocouple. In order to investigate the mechanical damage of the materials trough the fire, additional specimen were exposed to flame for 15s and the remaining compressive strength was determined. It was found that in particular a titanium foil under the top layer can contribute significantly to improvements in the mechanical properties as well as to slow down the temperature rise on the back of the material.