Development of a new modelling tool to better represent the interaction of lightning with aircraft composites

闪电是一种自然发生的现象，由云中的水和冰相互移动，转移电荷并积累电能引起。闪电通常发生在极端天气条件下，或雷暴，由于放电。放电非常快，在十分之一到百分之一秒的范围内。闪电可以被定义为闪光或罢工。雷击可以分为三种方式之一，这取决于它们的特定相互作用。如果放电保持在一个单一的云，它被归类为云内闪电（IC）。如果涉及一个以上，那么它是云对云（CC）闪电，最后一种类型是云对地（CG）闪电。云对地打击可以与地面或其他物体相互作用，例如高层建筑甚至飞机。平均而言，雷击与客机每年发生一次相互作用，大约每3000小时，在其运行寿命期间，可能对飞行安全产生不利影响。在飞机飞行期间，有两种情况可能发生雷击。这取决于飞机是否是罢工的原因或结果。在大多数情况下，飞机将被雷电的分支击中。然而，在某些情况下，当飞机进入大气层的高度带电区域时，它可能会触发闪电放电。当雷击与飞机相互作用时，会产生大量电流。该电流在导电通道上产生过热效应，其形成高度导电的等离子体通道。这会对飞机造成很大的损害。用金属机身对飞机进行电磁屏蔽是防止雷击造成损害的主要措施。然而，近年来，由于成本和重量目标，碳复合材料的使用在飞机工业中急剧增加。复合材料由于具有高的正交各向异性电阻率，遭受雷击时会产生较大的损伤。高的正交各向异性电阻率导致高的热负荷，这可能导致复合层片的分层。这一主题的研究集中在这种闪电现象的建模。这大致分为五类：热电，机械压力加载，热膨胀，内部热解压力加载和电磁脉冲。该项目的目的是开发模拟能力，以复制雷击期间发生的影响。这将有助于更好地了解雷击和飞机复合材料之间的独特相互作用。迄今为止，文献表明，为此目的的建模技术正在稳步发展，但也表明差距仍然存在。该项目旨在通过产生新的建模方法/工具来发展该领域的新知识，从而推动该学科的发展。这种建模方法可能会采取有限元和多物理场模拟的形式，以捕捉撞击过程中发生的材料变化和物理现象。

Lightning is a naturally occurring phenomenon caused by water and ice moving past each other in the clouds, transferring charges and building up electrical energy. Lightning typically occurs during extreme weather conditions, or electrical storms, as a result of an electrical discharge. The discharges are very quick, in the region of a tenth to one hundredth of a second. Lightning can be defined as either a flash or a strike. Lightning strikes can be classified in one of three ways, depending on their particular interactions. If the discharge remains within a single cloud it is classified as intra-cloud lightning (IC). If more than one is involved then it is cloud to cloud (CC) lightning and the final type is cloud to ground (CG) lightning. A cloud to ground strike can interact with the ground or other objects, e.g. tall buildings or even aircraft. On average a lightning strike interacts with an airliner once per year, approximately every 3000 hours, during its operating life and can have a detrimental effect on flight safety. During an aircraft's flight there are two scenarios which can occur with a lightning strike. These are dependent on whether the aircraft is the cause or result of the strike. In most cases the aircraft will be struck by a branch of lightning. However, in some cases, when the aircraft enters a highly charged region of the atmosphere it can be the trigger for the lightning discharge. When a lightning strike interacts with an aircraft there is a large flow of electrical current. This current produces a superheating effect on the conducting channel which forms a highly electrically-conductive plasma channel. This can cause large amounts of damage to the aircraft.Electromagnetic shielding of the aircraft by metallic airframes was the primary measure to prevent damage from a lightning strike. However, in recent years, due to cost and weight targets the use of carbon composite materials has dramatically increased in the aircraft industry. Composites suffer comparatively large damage from lightning strikes due to high orthotropic electric resistivity. The high orthotropic electric resistivity leads to high thermal loads which can cause delamination of the composite plies. Research of this topic has centered on modelling of this lightning phenomenon. This has broadly fallen into five categories; Thermal-electric, mechanical pressure loading, thermal expansion, internal pyrolysis pressure loading and electromagnetic pulses.The aim of this project is to develop the modelling capabilities to replicate the effects occurring during the lightning strike. This will allow for a better understanding of the unique interactions between the lightning strike and the aircraft composite. To date literature had shown the steady development of modelling techniques for this purpose but has also shown gaps still exist. This project will aim to advance the discipline by producing a new modelling approach/tool to develop new knowledge in the field. This modelling approach will likely take the form of finite element and multi-physics simulations to capture both the material changes and physics occurring during a strike.