Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging
Ultrasound non-destructive testing (NDT) is a common technique used for defect detection in different materials, from aluminium to carbon-fiber-reinforced polymers (CFRPs). In most cases, a liquid coupling medium/immersion of the inspected component is required to maximize impedance matching, limiti...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-02-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/21/4/1170 |
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| author | Marco Boccaccio Pasquale Rachiglia Gian Piero Malfense Fierro Giovanni Pio Pucillo Michele Meo |
| author_facet | Marco Boccaccio Pasquale Rachiglia Gian Piero Malfense Fierro Giovanni Pio Pucillo Michele Meo |
| author_sort | Marco Boccaccio |
| collection | DOAJ |
| description | Ultrasound non-destructive testing (NDT) is a common technique used for defect detection in different materials, from aluminium to carbon-fiber-reinforced polymers (CFRPs). In most cases, a liquid coupling medium/immersion of the inspected component is required to maximize impedance matching, limiting the size of the structure and materials. Air-coupled inspection methods have recently been developed for noncontact inspections to reduce contact issues in standard ultrasonic inspections. However, transmission of ultrasound in air is very inefficient because of the enormous impedance mismatch between solids and air, thus requiring a signal amplification system of high-sensitivity transducers. Hence, the captured signal amplitude may not be high enough to reveal any wave distortion due to defects or damage. This work presents a design of a holey-structured metamaterial lens with a feature size of λ/14 aiming at improvement of acousto-ultrasonic imaging using air-coupled transducers. The required effect is obtained by matching geometrical parameters of the proposed holey-structured metamaterials and the Fabry–Perot resonance modes of the structure. Transmission tests have been conducted on different fabricated metamaterial-based structures, to assess the frequency component filtering of the proposed method in both acoustic (f = 5 kHz, 20 kHz) and ultrasonic range (f = 30 kHz, 40 kHz). Results showed an improved sensitivity of damage imaging, with an increase in amplitude of the design frequencies of the lens by 11 dB. Air-coupled inspections were conducted on a stress-corrosion cracked aluminum plate and impacted CFRP plate using the holey-structured lens. Results showed an improvement in the damage-imaging resolution due to a wave-amplitude increase across the defective features, thus demonstrating its potential as an efficient and sensitive inspection tool for damage-detection improvement in geometrically complex components of different materials. |
| first_indexed | 2024-03-09T05:14:58Z |
| format | Article |
| id | doaj.art-6af981987671419fb4610f04aa37db74 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-09T05:14:58Z |
| publishDate | 2021-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-6af981987671419fb4610f04aa37db742023-12-03T12:46:19ZengMDPI AGSensors1424-82202021-02-01214117010.3390/s21041170Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic ImagingMarco Boccaccio0Pasquale Rachiglia1Gian Piero Malfense Fierro2Giovanni Pio Pucillo3Michele Meo4Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UKDepartment of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UKDepartment of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UKDepartment of Industrial Engineering, University of Naples Federico II, 80125 Naples, ItalyDepartment of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UKUltrasound non-destructive testing (NDT) is a common technique used for defect detection in different materials, from aluminium to carbon-fiber-reinforced polymers (CFRPs). In most cases, a liquid coupling medium/immersion of the inspected component is required to maximize impedance matching, limiting the size of the structure and materials. Air-coupled inspection methods have recently been developed for noncontact inspections to reduce contact issues in standard ultrasonic inspections. However, transmission of ultrasound in air is very inefficient because of the enormous impedance mismatch between solids and air, thus requiring a signal amplification system of high-sensitivity transducers. Hence, the captured signal amplitude may not be high enough to reveal any wave distortion due to defects or damage. This work presents a design of a holey-structured metamaterial lens with a feature size of λ/14 aiming at improvement of acousto-ultrasonic imaging using air-coupled transducers. The required effect is obtained by matching geometrical parameters of the proposed holey-structured metamaterials and the Fabry–Perot resonance modes of the structure. Transmission tests have been conducted on different fabricated metamaterial-based structures, to assess the frequency component filtering of the proposed method in both acoustic (f = 5 kHz, 20 kHz) and ultrasonic range (f = 30 kHz, 40 kHz). Results showed an improved sensitivity of damage imaging, with an increase in amplitude of the design frequencies of the lens by 11 dB. Air-coupled inspections were conducted on a stress-corrosion cracked aluminum plate and impacted CFRP plate using the holey-structured lens. Results showed an improvement in the damage-imaging resolution due to a wave-amplitude increase across the defective features, thus demonstrating its potential as an efficient and sensitive inspection tool for damage-detection improvement in geometrically complex components of different materials.https://www.mdpi.com/1424-8220/21/4/1170metamaterialholey lensnonlinear ultrasonicsdeep-subwavelengthair-couplednon-destructive testing |
| spellingShingle | Marco Boccaccio Pasquale Rachiglia Gian Piero Malfense Fierro Giovanni Pio Pucillo Michele Meo Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging Sensors metamaterial holey lens nonlinear ultrasonics deep-subwavelength air-coupled non-destructive testing |
| title | Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging |
| title_full | Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging |
| title_fullStr | Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging |
| title_full_unstemmed | Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging |
| title_short | Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging |
| title_sort | deep subwavelength optimized holey structured metamaterial lens for nonlinear air coupled ultrasonic imaging |
| topic | metamaterial holey lens nonlinear ultrasonics deep-subwavelength air-coupled non-destructive testing |
| url | https://www.mdpi.com/1424-8220/21/4/1170 |
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