Health monitoring and damage prognosis of aircraft composite structures

通过充分预测复合材料结构的剩余使用寿命来进行健康监测是航空航天界感兴趣的一个主要领域，在航空航天界，不断增长的维护费用（估计每年全球为100亿美元）可能会缩短其经济寿命。拟议的研究计划的目标是设计和制造集成有光纤传感器的先进复合材料，以监测制造过程，并使用相同的传感器网络开发一种损伤预测方法，以逐步取代目前的基于时间表的维护任务，其中部件在预先确定的周期数后进行检查，通过基于条件的维护，其中部件在达到不足的剩余使用寿命之前被维护。 可用于监测飞行器部件的健康的当前系统和技术主要基于负载监测系统，该负载监测系统确定飞行参数，并且使得能够通过诸如射线照相术、涡流、超声波或其他适当方法的小区域扫描过程得出关于在飞行期间发生的负载水平的结论，或者进行定期维护。现有的方法是耗时且成本密集的。因此，非破坏性评估技术的可用性，这使得结构健康评估的飞机部件的一个组成部分，称为结构健康监测，是至关重要的，在减少时间和成本与维护组件的可靠性。SHM是一项新兴技术，涉及结构的连续监测，检查和损伤检测的技术和系统的开发，以最小的劳动参与。 SHM的重点是找到非常关键的问题的答案：（i）结构中的损伤存在及其类型，（ii）损伤是局部的还是全局的（例如，一个大的孤立裂纹或许多小的缺陷分布在材料中），（iii）损坏的位置，无论是在材料中或在接缝和连接（或两者），和（iv）最终找出是否结构可能会失败，由于损坏的存在。

Health monitoring through adequate prediction of the remaining useful life of composite structures is a major area of interest for the aerospace community where the growing maintenance costs, estimated to $10 billion worldwide annually, can reduce their economic life. The objective of the proposed research program is to design and manufacture advanced composites integrated with fiber optic sensors to monitor the manufacturing process and to use the same sensor network to develop a damage prognostic approach to gradually replace current schedule-based maintenance tasks, where components are inspected after a pre-established number of cycles, by condition-based maintenance, where components are maintained prior to attaining an insufficient remaining useful life. The current systems and technologies available for monitoring the health of the aircraft components are mostly based on load monitoring systems that determine flight parameters, and enable conclusions to be drawn concerning the load levels occurred during the flight, or scheduled maintenance by means of small area scanning processes such as radiography, eddy currents, ultrasonic or other appropriate methods. The existing methods are time consuming and cost intensive. Therefore, the availability of a non-destructive evaluation technology, which makes the structural health assessment an integral part of the aircraft components, known as Structural Health Monitoring, is crucial in terms of reducing time and cost associated with maintaining reliability of components. SHM is an emerging technology, dealing with the development of techniques and systems for the continuous monitoring, inspection and damage detection of structures, with minimum labor involvement. The SHM focuses on finding answers to the very critical questions on: (i) damage existence in a structure and its type, (ii) whether the damage is local or global (e.g., a large isolated crack or many small defects distributed in the material), (iii) the location of the damage whether the damage is in the material or in the joints and connections (or both), and (iv) finally find out whether the structure is likely to fail due to the presence of damage.