航空航天用碳纤维复合材料雷电直接效应的机理研究

Lightning, which is a kind of nature discharging phenomenon accompanying with high voltage and high current, caused great damage to the safe operation of airspace vehicles. With the improvement of aircraft design and carbon fiber composite technology, carbon fiber reinforced polymer composites(CFRP) have been widely used in airspace field, such as Large Civil Aircraft, Military Aircraft, Unmanned Aerial Vehicle(UAV) and Stealth Aircraft.The Boeing B787 dreamliner features over 50% CFRP by structural weight, including wing, tail, and body structure, and the ratio of CFRP structural reaches to 53% in the Airbus A350XWA. Dueing to much lower electrical conductivity of CFRP laminate, the lightning strike damage of CFRP laminate is far greater than that of the tranditional used metallic meterials in aircraft. But so far, there is not any correlative test standards can be abided for studying the lightning direct effects on CFRP. Taking the lightning direct effects on CFRP as the research background in the project, the experimental environment is established and the experimantal researches are carried. The test methods and measuring methods are searched, and the interaction between lightning cuurenr parameters and lightning direct effects on CFRP can be obtained. On base of the above experimental results, the physical models of CFRP are built and the calculated methods are designed, the innate relations between lightning current waveform parameters(including current peak i, rise rate of current di/dt, transfer charge Q and action integral W/R) and lightning stirke damage of CFRP (including carbon fiber breakage, resin pyrolysis, and thickness delamination) are obtained. Next, combining with the obtained experimental results, the simulating physical models are optimized, and the lightning strike damage mechanisms of CFRP are analyzed and searched. These research results will provide a theoretical basis for choosing high quality CFRP materials and the refined design of CFRP's structure, and they also lay a experimental and theoretical foundation for normalizing the test lightning waveforms,the test methods and the lightning direct effect on CFRP simultaneously.

雷电是自然界存在的高电压大电流放电现象，对航空航天器的安全运行危害极大。随着碳纤维增强型聚合物复合材料CFRP的技术进步，CFRP广泛应用在民用飞机、军用飞机及隐形飞机上，波音B787主翼、尾翼、机体等结构中CFRP的比例达到50%。但CFRP的雷击损伤远大于传统金属材料，而CFRP雷电直接效应的试验和测试方法至今尚无规范。 本项目以CFRP雷电直接效应为研究背景，探索雷电与CFRP相互作用的试验和测量方法，得到雷电流参数与CFRP雷电直接效应的相关规律。在此基础上，建立CFRP雷电直接效应的物理模型,获得雷电流参数与CFRP纤维断裂、树脂热解和深度分层的内在规律，并根据实验数据优化物理模型和计算方法，阐释CFRP的雷击损伤机理，为CFRP材料优选、CFRP结构设计提供理论依据，同时，为CFRP雷电直接效应试验与测量方法的规范及CFRP雷电直接效应试验标准的制定奠定实验与理论基础。

随着碳纤维复合材料CFRP的技术进步，在民用飞机、军用飞机及隐形飞机上获得了广泛应用，但CFRP的雷击损伤远大于传统金属材料。本项目以CFRP雷电直接效应为研究背景，探索雷电与CFRP相互作用的试验和测量方法，得到雷电流参数与CFRP雷电直接效应的相关规律；建立CFRP雷电直接效应的物理模型,获得雷电流参数与CFRP纤维断裂、树脂热解和深度分层的内在规律，建立CFRP的物理模型和计算方法，阐释CFRP的雷击损伤机理，为CFRP材料优选、CFRP结构设计提供理论依据。主要研究成果如下：.1）提出了用改进型三电极测量方法，得到了不同铺层结构的配方碳纤维复合材料的体电阻随外施直流电压的变化规律，高导电铺层及高导电铺层数的增加可以显著改善CFRP层合板的体积电阻率。.2）开展了非破坏雷电流分量作用下碳纤维复合材料动态特性的研究，发现在雷电流的阻抗呈现显著的非线性特征，且随着雷电流分量上升速率的减低和持续时间的增长，CFRP层合板的动态电导率呈现越来越大的趋势。.3）建立了碳纤维复合材料层合板的热电耦合模型，通过计算雷电作用过程中层合板瞬态温度场分布，结合碳纤维铺层之间树脂的热解行为，并对复合材料烧蚀扩展行为进行了研究，结果表明：雷击过程中，复合材料的损伤深度与损伤面积在雷击初始阶段迅速增加，随后变化较为缓慢；铺层的损伤在自身电流传导产生的电阻热以及层与层之间的热传导共同作用下具有方向性的不断扩展。.4）建立了多重连续时序雷电直接效应测试平台，开展不同组合的多重连续雷电流作用下CFRP层合板的损伤程度变化规律的研究，发现造成CFRP雷击深度损的主要原因是高幅值、高上升梯度的雷电流A、B及D分量产生的局部热效应和介质击穿，造成雷电附着点碳纤维和树脂的瞬时破裂，使得损伤深度增加；而CFRP损伤面积主要与雷电流的热效应有关，当雷电流在碳纤维散流时，热效应造成树脂热解及大量碳纤维的烧蚀甚至升华，从而造成损伤面积的增大。