An Empirical Study on Transmission Beamforming for Ultrasonic Guided-Wave Based Structural Health Monitoring

Abstract

The development of reliable structural health monitoring techniques is enabling a healthy transition from preventive to condition-based maintenance, hence leading to safer and more efficient operation of different industries. Ultrasonic guided-wave based beamforming is one of the most promising techniques, which supports the monitoring of large thin-walled structures. However, beamforming has been typically applied to the post-processing stage (also known as virtual or receiver beamforming) because transmission or physical beamforming requires complex hardware configurations. This paper introduces an electronic structural health monitoring system that carries out transmission beamforming experiments by simultaneously emitting and receiving ultrasonic guided-waves using several transducers. An empirical characterization of the transmission beamforming technique for monitoring an aluminum plate is provided in this work. The high signal-to-noise ratio and accurate angular precision of the physical signal obtained in the experiments suggest that transmission beamforming can increase the reliability and robustnessof this monitoring technique for large structures and in real-world noisy environments.

Ultrasonic Guided Wave Testing on Cross-Ply Composite Laminate: An Empirical Study

“…Procedure P2, which employs several PWAS, allows for more energy to be transmitted without jeopardizing their integrity. Their use with delayed multiple emission techniques does not create a main beam, as it does in any material with isotropic behavior [ 29 ], but it allows for multiple tests in different directions where the acquired signals show different waveforms ( Figure 15 ). The wave front can be focused on specific direction by tuning the delay between adjacent PWAS.…”

“…A more precise test, not shown in this paper, determined that 1.60 µs delay provide the highest amplitudes in reception. This set of tests shows that the delayed multiple emission technique on composite material does not create a main narrow beam, as it does on isotropic materials, while it is named the transmission beamforming technique [ 29 ]. All in all, there is a delay that originates the maximum amplitude in a given direction.…”

“…In the study, the same signal is transmitted through all the PWAS, but a delay is added to the signal for each PWAS. Cantero-Chinchilla et al [ 29 ] show a practical study of the application of this technique in aluminum specimens. They report the formation of a main beam with the technique.…”

Structural Health Monitoring Using Ultrasonic Guided-Waves and the Degree of Health Index

“…The damage index is based on pattern matching using fuzzy logic fundamentals, which provide it with robustness against measurement uncertainties. The adoption of the transmission beamforming technique for SHM entails the collection of large amount of data [ 46 , 51 ]. This allows a more robust damage detection, providing redundancy and ensuring an accurate monitoring in the event of hardware failure, for example, sensor malfunction.…”

“…Furthermore, the transmission beamforming technique [ 46 ] has been adopted for the monitoring of the specimen during the fatigue test. Using this technique, synchronously delayed signals were applied to the T PWAS (refer to Figure 3 a), so that the wave fronts can be constructively summed at a pre-established direction creating a main wave beam [ 47 ].…”