Characterization of guided wave propagation in aircraft structures

结构健康监测（SHM）是航空航天界感兴趣的一个主要领域，特别是考虑到全球每年不断增长的维护成本估计为104亿美元的老化飞机。该行业的5到10年目标是部署SHM系统，该系统将满足在役检测要求，将传感器永久安装在结构上，与基线检测方法相比，提供经济效益。提出了利用导波传播技术对机体结构进行嵌入式监测的方法。然而，在复杂结构中，波的传播和与缺陷的相互作用在文献中只针对特定和有限数量的部件和缺陷类型进行了讨论。例如，在一定程度上研究了金属接头与裂纹的相互作用以及复合接头的脱粘现象。这项基于知识缺口的研究的目的是为行业提供各种基本飞机结构或标准的扩展知识库，从中可以推断其他特定结构的导波传播和与缺陷的相互作用。知识库将包含诸如在结构中传播或与缺陷相互作用的模式类型、波的衰减、波的空间模式和色散曲线等参数。该项目的具体目标是：1)开发表征导波传播的标准过程；2)开发各种常见飞机结构的导波特性知识库；3)开发各种常见飞机结构的导波与损伤相互作用机制知识库；4)提出飞机结构中导波的SHM设计准则。这样的知识库将允许工业合作伙伴通过减少用于损坏监测的SHM应用程序验证和资格所需的测试来优化传感配置并最大限度地缩短开发时间。

Structural health monitoring (SHM) is a major area of interest for the aerospace community, especially considering aging aircraft where the growing maintenance costs estimated to $10,4 billion worldwide annually. The 5 to 10 years goal of the industry is to deploy SHM systems which will 1) meet the in-service inspection requirements with sensors permanently installed on the structure and 2) provide economic benefits compared to the baseline inspection methods. Strategies using guided wave propagation have been proposed for embedded monitoring of airframe structures. However, wave propagation and interaction with defects in complex structures is addressed in the literature only for specific and limited number of components and types of defects. For example, interaction with cracks in metallic joints and debonding in composite joints has been investigated to some extent. The objective of this knowledge-gap based research is to provide the industry with an extended knowledge base for a variety of basic aircraft structures, or standards, from which the guided wave propagation and interaction with defects for other specific structures could be inferred from. The knowledge base will contain parameters such as the type of modes propagating in the structures or interacting with defects, the attenuation of the waves, the spatial pattern of the waves and the dispersion curves. The specific objectives of the project are: 1) develop a standard process to characterize guided wave propagation, 2) develop a knowledge base of guided wave characteristics for a variety of common aircraft structures, 3) develop a knowledge base of guided wave interaction mechanisms with damage for a variety of common aircraft structures and 4) propose SHM design criteria for guided waves in aircraft structures. Such a knowledge base would allow industrial partners to optimize sensing configuration and minimize development time, by reducing required testing for validation and qualification of SHM applications for damage monitoring.