Study On Fireproof Characteristics And Compliance For Airworthiness Of Typical Aircraft Composites

Physical properties of composite materials are excellent,and its specific strength and specific modulus are superior to metallic materials.It is a new type of aviation materials which has been widely used in aviation,especially in the field of civil aviation.However,the composites will be decomposed and burnt in the high temperature or flame environment,producing a large amount of heat,smoke and poisonous gases.The mechanical properties of the composites will be degraded,and the integrity of the aircraft structure will be destroyed.And consequently it will pose a devastating threat to the effective evacuation of personnel and the flight safety of the aircraft.At the same time,there are little researches on the flame-through characteristics of composite materials in the current airworthiness standards whatever at home or abroad.Therefore,it is very important to study the fire-resistant performance of aircraft composites.In this paper,T700 carbon fiber epoxy composites were as the main research object.The macro-fire test and microscopic characterization test(thermogravimetric analysis,IPDT integral pyrolysis temperature,and pyrolysis kinetics)are performed to study the influence of scrubbing airflow and vibration conditions on the severity of airworthiness fire test and the fire-resistant performance of T700 carbon fiber epoxy composites in the flame environment.And the effects of foam core and T700 carbon fiber epoxy composites on combustion and smoking characteristics were investigated by cone calorimeter and smoke density box.The results show that the condition of scrubbing air flow has a significant cooling protection effect on the flame resistance of the material which reduces the severity of the airworthiness fire test conditions.The vibration conditions slightly exacerbate the fire penetration of the materials in the flame environment which has little influence on the severity of the test.Foam core has little effect on the ignition time of T700 carbon fiber / epoxy-foam sandwich panel.However,due to the involvement of foam core in pyrolysis and combustion of epoxy,the peak heat release rate(pkHRR),total heat release and total smoke output of T700 carbon fiber / epoxy composites were increased.In addition,the foam core material was involved in the formation of epoxy charcoal process,resulting in peak smoke rate and smoke production duration of T700 carbon fiber / epoxy-foam sandwich panel are significantly increased compared to T700 carbon fiber / epoxy composite material.At the same time,the foam core material exacerbates the smoke production and toxicity of T700 carbon fiber /epoxy-foam sandwich.