Health Monitoring of Structures in the Scope of Airframe Structural Testing

Kurzfassung

The development of large civil aircrafts is an engineering task of significant complexity, requiring, besides engineering skills, time and immense investment to be complete. Besides obvious economic motivation in the aerospace and airline industry worldwide, is the availability and affordability of modern, safe aircrafts with less emissions believed to be of global significance. The airframe development is subject to constant innovation in various fields of aerospace. The required fatigue testing of large-scale aircraft structures has shown to be time-consuming in itself, sometimes up to the point where it determines the pace of development, not just by the eventual test results that testing provides for aircraft development and certification. This work shows how Structural Health Monitoring can contribute to innovation in the way full-scale airframe structures are tested with the objective to reduce time and cost. The use of Structural Health Monitoring in aerospace has foremost been pursued in the context of in-service aircraft maintenance with a replacement of conventional means like NDT in mind. SHM has been applied to structural tests in the past often with technologies and systems intended for in-service use. This work provides an overview on the motivation and associated requirements for use of SHM for airframe structural test, which are the basis to then define a conceptual framework and assess different SHM technologies with the intent of holistic and efficient application. This work focuses thereafter on Guided Waves (GW) as the selected SHM technology for development, test and assessment, which was applied on a large scale composite aerospace panel [1]. The GW SHM system, previously designed for in-service application, was adapted in terms of data acquisition and data management and integrated with the overall test stand and a dedicated data management and data processing environment. That enabled a novel dedicated signal processing framework, as it provides damage detection capability under variable environmental and operational conditions, as well as the transient loading condition of a fatigue test. The test set-up was representative for fuselage tests and solely available for the purpose of the research project. That allowed us to define and execute an experimental test of the GW SHM system with test conditions representative for typical fuselage fatigue tests. The work concludes with an analysis of the test results with respect to the requirements and a reflection of their significance for the conceptual framework of SHM for structural test. [1] Moix-Bonet, Maria und Schmidt, Daniel und Eckstein, Benjamin und Wierach, Peter (2024) A Composite Fuselage under Mechanical Load: a case study for Guided Wave-based SHM. In: 11th European Workshop on Structural Health Monitoring, EWSHM 2024. NDT.net. EWSHM 2024, 2024-06-10, Potsdam, Deutschland. doi: 10.58286/29842. ISSN 1435-4934.