Research on continuous leakage location of stiffened structure based on frequency energy ratio mapping method

Abstract

The stiffened structure has a complex effect on signal propagation and poses difficulties in leakage location technology. In order to solve this problem, this paper proposes a frequency energy ratio mapping method (FERMM). The method divides the grid on the structure in advance, compares the signal of the distributed sensor with the reference signal to generate a mapping matrix frome the energy ratio vector. When a leak at an unknown location occurs, the energy ratio vector is formed by the same method and matched with the mapping matrix to locate the unknown leakage. The energy ratio vector of this method are only related to the propagation path and are independent of the spectral characteristics of the leakage and the frequency response characteristics of the receiving sensor. FERMM has the adaptability to complex structures and can locate continuous signals for a fast real-time process. The FERMM was verified by 120 sets of experiments. The results show that the average positioning error of FERMM is 25.5 mm, which can reach 14.4 mm error under the optimal setting of grid coincidence.

Lamb Wave Scattering Analysis for Interface Damage Detection between a Surface-Mounted Block and Elastic Plate

“…Sherafat et al [ 20 ] considered GW-based SHM for inspection of a skin–stringer panel made of quasi-isotropic plates bonded together with an adhesive film and presented some guidelines related to the selection of the optimal mode and frequency range for debonding inspection based on a scattering analysis. Zhang et al [ 21 ] proposed the frequency energy ratio mapping method to detect a leakage source’s location for stiffened structures using a sensor network and a mapping matrix formed by the frequency-domain energy ratio vectors.…”

Noncontact Damage Topography Reconstruction by Wavenumber Domain Analysis Based on Air-Coupled Ultrasound and Full-Field Laser Vibrometer

“…In laser ultrasound, laser Doppler vibrometers are often used as testing equipment, and the Doppler frequency shift phenomenon is used to measure the in-plane or out-of-plane surface vibration displacement and velocity [10]. The laser-related technology can perform spatial distributed detection, has a high spatial resolution, and can detect large-size or complex curved surfaces [11,12]. Air-coupled ultrasound technology uses air as the coupling medium between the transducer and the structure, which can generate bulk waves, surface waves and also Lamb waves.…”