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3 results on '"SHM APPLICATIONS"'

1. PMUTs Arrays for Structural Health Monitoring of Bolted-Joints.

Author

Abdalla, Omer M. O., Massimino, Gianluca, Quaglia, Fabio, Passoni, Marco, and Corigliano, Alberto

Subjects
STRUCTURAL health monitoring, TRANSMISSION of sound, BOLTED joints, ULTRASONIC testing, MICROELECTROMECHANICAL systems, ULTRASONIC transducers
Abstract

Micro-electro-mechanical systems (MEMS) have enabled new techniques for the miniaturization of sensors suitable for Structural Health Monitoring (SHM) applications. In this study, MEMS-based sensors, specifically Piezoelectric Micromachined Ultrasonic Transducers (PMUT), are used to evaluate and monitor the pre-tensioning of a bolted joint structural system. For bolted joints to function properly, it is essential to maintain a suitable level of pre-tensioning. In this work, an array of PMUTs attached to the head and to the end of a bolt, serve as transmitter and receiver, respectively, in a pitch-catch Ultrasonic Testing (UT) scenario. The primary objective is to detect the Change in Time of Flight (CTOF) of the acoustic wave generated by the PMUT array and propagating along the bolt's axis between a non-loaded bolt and a bolt in service. To model the pre-tensioning of bolted joints and the transmission of the acoustic wave to and from a group of PMUTs through the bolt, a set of numerical models is created. The CTOF is found to be linearly related to the amount of pre-tensioning. The numerical model is validated through comparisons with the results of a preliminary experimental campaign. [ABSTRACT FROM AUTHOR]

Published
2023
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2. PMUTs Arrays for Structural Health Monitoring of Bolted-Joints

Author

Omer M. O. Abdalla, Gianluca Massimino, Fabio Quaglia, Marco Passoni, and Alberto Corigliano

Subjects
piezoelectric micromachined ultrasonic transducers, ultrasound, multiphysics modelling, SHM applications, acoustoelastic effect, Mechanical engineering and machinery, TJ1-1570
Abstract

Micro-electro-mechanical systems (MEMS) have enabled new techniques for the miniaturization of sensors suitable for Structural Health Monitoring (SHM) applications. In this study, MEMS-based sensors, specifically Piezoelectric Micromachined Ultrasonic Transducers (PMUT), are used to evaluate and monitor the pre-tensioning of a bolted joint structural system. For bolted joints to function properly, it is essential to maintain a suitable level of pre-tensioning. In this work, an array of PMUTs attached to the head and to the end of a bolt, serve as transmitter and receiver, respectively, in a pitch-catch Ultrasonic Testing (UT) scenario. The primary objective is to detect the Change in Time of Flight (CTOF) of the acoustic wave generated by the PMUT array and propagating along the bolt’s axis between a non-loaded bolt and a bolt in service. To model the pre-tensioning of bolted joints and the transmission of the acoustic wave to and from a group of PMUTs through the bolt, a set of numerical models is created. The CTOF is found to be linearly related to the amount of pre-tensioning. The numerical model is validated through comparisons with the results of a preliminary experimental campaign.

Published
2023
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3. Relative Ability of Wedge-Coupled Piezoelectric and Meander Coil EMAT Probes to Generate Single-Mode Lamb Waves

Author

Pouyan Khalili, Peter Cawley, and Engineering & Physical Science Research Council (EPSRC)

Subjects
Technology, Materials science, PIPE INSPECTION, Acoustics and Ultrasonics, Acoustics, 01 natural sciences, 09 Engineering, higher order mode cluster (HOMC), A(0) MODE, symbols.namesake, Engineering, Lamb waves, DESIGN, COMB TRANSDUCERS, EXCITATION, 0103 physical sciences, Wavenumber, Electrical and Electronic Engineering, SHM APPLICATIONS, 010301 acoustics, Instrumentation, Electromagnetic acoustic transducer, 010302 applied physics, Science & Technology, 02 Physical Sciences, guided waves, Single-mode optical fiber, Electromagnetic acoustic transducer (EMAT), Engineering, Electrical & Electronic, AXISYMMETRICAL GUIDED-WAVES, DEFECTS, INTERDIGITAL PVDF TRANSDUCERS, mode selectivity, Fourier transform, Transducer, fast Fourier transform (FFT), Surface wave, modal decomposition, MAGNETOSTRICTIVE TRANSDUCER, symbols, Ultrasonic sensor
Abstract

Ultrasonic guided waves are used extensively when checking for defects in petrochemical and other industries and are mostly generated using piezoelectric transducers on an angled wedge or electromagnetic acoustic transducers (EMATs) in different configurations. Low-frequency inspection allows for long-distance propagation, but it is best suited for detecting relatively large defects, while at higher frequencies, the presence of multiple wave modes limit defect detectability, so achieving practical single Lamb mode excitation via careful transduction is very beneficial. This paper investigates the relative ability of angled piezoelectric and meander coil EMAT probes to produce single-mode transduction in the medium (~1–5 MHz-mm) and high (>5 MHz-mm) frequency-thickness regions of the dispersion curves. The nature of each transducer is studied analytically by simulating the corresponding surface forces, followed by the use of a Fourier transform in time and space (2-D fast Fourier transform) to highlight the excitation region in the wavenumber–frequency space. With angled wedge excitation there is a linear relationship between the excitation frequency and the wavenumber which means that the excitation tends to track typical dispersion curves, allowing for easier pure mode generation. In contrast, the EMAT controls frequency and wavenumber separately which makes it more difficult to generate a pure mode when dispersion curves are close together; however, by narrowing the frequency bandwidth via a large number of cycles in the excitation signal, pure mode generation via an EMAT was shown to be possible even in areas of closely spaced modes. As example cases, analytical results, backed up by experiments, showed that signals dominated by the A0 mode at 1.5 MHz-mm and also the A1 mode at 18 MHz-mm can be generated with both angled piezoelectric and EMAT probes.

Published
2018
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