Monitoring network for SHM in aircraft applications

Abstract

The presented paper describes a condition monitoring for Aircraft structures based on the evaluation of acoustical Lamb waves. Methods for effective sensor near signal processing are required to detect wave modes and to reduce noise as much as possible. Frequently, a further necessity exists to integrate the measuring technique into the monitored structure. To meet these requirements, sensor near units for signal processing have to be developed, which can be connected as nodes within a network. A compact, sensor near signal processing structure has been realized containing components for analog preprocessing of acoustic signals, their digitization, algorithms for data reduction and network communication. The core component is a digital signal processor (DSP), which performs the basic algorithms necessary for filtering, down sampling, mode selection and correlation of spectral components particularly effective. As a first application, impact detection and characterization of delaminations were realized for a fiber composite plate. Starting from the simulation of wave propagation, characteristic signal parameters were determined. In some experiments, it could be proven that impact locations and delaminations can be derived from the detected Lamb waves. This work is continued to develop special structural health monitoring systems (SHM) for selected aircraft components (e. g. stringer elements, panels)

Predictive model of fatigue crack detection in thick bridge steel structures with piezoelectric wafer active sensors

“…Today the majority of work concerns the propagation of Lamb waves in thin structures. Regarding the interaction of Lamb waves with different types of damage, many experimental studies are: detection of impact (Frankenstein et al 2006), cracks (Grondel et al 2002) or corrosion (Titry et al 2004). For this reason it is very important to study the Lamb wave propagation in thick steel plates to understand the difficulties in analyzing these waves.…”