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Active Structural Integrity Monitoring of the Aircraft Based on the PZT Sensor Network—The SYMOST Project
Abstract
This paper presents an approach to the health monitoring of the PZL–130 TC II Orlik aircraft structure during the full scale fatigue test (FSFT). The results of the final stage of the project which main aim was to develop a system for the aircraft structure monitoring will be presented. A network of PZT piezoelectric transducers was assembled on the aircraft structure and a dedicated hardware enabling remote control and programmed measurement performance was elaborated. A multichannel acquisition system of large dataset of measurements from the ‘hot-spot’ locations of the sensors on different stages of the fatigue tests is described in the paper. The system components are: remote monitoring unit, signal analysis, graphical user interface, sensor self-diagnostic tools, and data classification model. During the test of the aircraft, fatigue cracks were found and verified based on a detailed NDT schedule as well as Resistance Crack Gauges (RG) at particular locations. In the adopted approach a set of Damage Indices (DI’s), carrying marginal signal information content and correlated with the total energy received by a given sensor are proposed. The paper provides the description of elaborated techniques for the signal processing and inference about the damage presence. In particular some issues concerning the damage growth monitoring are discussed and the so called Averaged Damage Indices (ADI’s) introduced. Damage detection capabilities are exemplified by data collected from selected network nodes where damages were found during the project run and the results of their monitoring will be highlighted. The necessity of the use of NDE assisted technology for early damage detection has been proven within the project, especially for the ‘hard to access’ locations in the aircraft structure.