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，因为维修费用不断增加，估计全世界每年要花费100亿美元，这可能会缩短复合材料结构的经济寿命。拟议研究计划的目标是设计和制造集成光纤传感器的先进复合材料，以监控制造过程，并使用相同的传感器网络开发损坏预测方法，逐步取代当前基于计划的维护任务，其中组件在预先确定的周期数之后进行检查，通过基于状态的维护。组件在达到不足的剩余使用寿命之前进行维护。目前可用于监测飞机部件健康状况的系统和技术主要基于负载监测系统，该系统确定飞行参数，并通过小区域扫描过程（如射线照相、涡流、超声波或其他适当方法）得出关于飞行期间发生的负载水平或定期维护的结论。现有的方法耗时长，成本高。因此，一种非破坏性评估技术的可用性，使结构健康评估成为飞机部件的一个组成部分，被称为结构健康监测，在减少与保持部件可靠性相关的时间和成本方面至关重要。SHM是一项新兴技术，涉及技术和系统的发展，用于连续监测，检查和结构损伤检测，以最少的人工参与。单孔位微吹气扰动主要用来寻找最关键问题的答案:(i)损害存在的结构及其类型,(2)损伤是否本地或全球(比如,一个大型孤立的裂纹或许多小缺陷分布的材料),(3)损伤是否损伤的位置是在材料或关节和连接(或两者),和(iv)最终确定可能失败是由于结构损伤的存在。

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.