Selecting optimum air gap length in air-coupled ultrasonic through-transmission testing of products made of polymer materials

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Abstract

In air-coupled ultrasonic non-destructive testing of a number of products (biological objects, products made of chemically active or explosive materials), the amplitude of the electrical signal applied to the transmitting piezoelectric transducer is limited and in some cases cannot exceed the value of the order of U ~ 10—15 V. In this case, the sensitivity of testing is significantly reduced and therefore all possible ways to increase it should be used. First of all, piezoelectric transducers with the highest possible electroacoustic conversion coefficient should be used. In addition, it is necessary to select such an air gap length da between the transmitting transducer and the test object, that ensures the maximum amplitude of the ultrasonic emission signal “at the input” of the product. And since the maximum amplitude of the ultrasonic signal emitted by the transducer is located in the near field of the transducer, it is necessary to select the value da corresponding to the length of the near field of the transmitting transducer in the air, provided that in this case there will be no re-reflections of the emission signals in the air gap. This in turn requires the use of short (broadband) ultrasonic signals and, consequently, the use of ultrasonic broadband piezoelectric transducers.

The article shows that the parameters of the matching layers of the air-coupled ultrasonic piezoelectric transducer affect both the bandwidth of the transducer and the spatial characteristics of the transducer, including the position of the acoustic field maximum. It is shown that it is possible to determine the maximum of the ultrasonic broadband signal in the air in order to determine the optimal length of the air gap, at which the ultrasonic signal with maximum amplitude is emitted into the product, by analyzing the correlation distribution of the field of an air-coupled broadband transducer.

The results of the experiments are presented, confirming the necessity of providing the optimal length of the air gap between the air-coupled ultrasonic transmitting transducer and the test object to increase the sensitivity of through-transmission testing of simulators of products made of explosive materials.

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About the authors

Vladimir K. Kachanov

National Research University “Moscow Power Engineering Institute”

Email: kachanovvk@mail.ru
Russian Federation, 111250 Moscow, Krasnokazarmennaya str., 17

Igor V. Sokolov

National Research University “Moscow Power Engineering Institute”

Email: sokoloff_igor@mail.ru
Russian Federation, 111250 Moscow, Krasnokazarmennaya str., 17

Michal A. Karavaev

National Research University “Moscow Power Engineering Institute”

Author for correspondence.
Email: vezd@list.ru
Russian Federation, 111250 Moscow, Krasnokazarmennaya str., 17

References

  1. Vavilov V.P. Thermal nondestructive testing: development of conventional directions and new trends (a review) // Defectoskopiya. 2023. No. 6. P. 38—58.
  2. Kladov D.Y., Chulkov A.O., Vavilov V.P., Stasevskii V.I., Yurkina V.A. Effectiveness of using thermal imagers of various types in active thermal testing of delaminations in nonmetals // Defectoskopiya. 2023. No. 7. P. 25—32.
  3. Shpil’noi V.Y., Vavilov V.P., Derusova D.A., Druzhinin N.V., Yamanovskaya A.Yu. Specific features of nondestructive testing of polymer and composite materials using air-coupled ultrasonic excitation and laser vibrometry // Defectoskopiya. 2021. No. 8. P. 14—23.
  4. Derusova D.A., Vavilov V.P., Nekhoroshev V.O., Shpil’noi V.Yu., Druzhinin N.V. Features of laser-vibrometric nondestructive testing of polymer composite materials using air-coupled ultrasonic transducers // Defectoskopiya. 2021. No. 12. P. 26—38.
  5. Essig W., Bernhardt Y., Döring D., Solodov I., Gautzsch T., Gaal M., Hufschläger D., Sommerhuber R., Marhenke T., Hasener J., Szewieczek A., Hillger W. Air-coupled ultrasound — emerging NDT method // ZfP-Zeitung. 2021. V. 173. P. 32—43.
  6. Asokkumar A., Jasiuniene E., Raišutis R., Kažys R. Comparison of ultrasonic non-contact air-coupled techniques for characterization of impact-type defects in pultruded GFRP composites // Materials. 2021. V. 14. Is. 5.
  7. Quattrocchi1 A., Freni1 F., Montanini R. Air-coupled ultrasonic testing to estimate internal defects in composite panels used for boats and luxury yachts // International Journal on Interactive Design and Manufacturing. 2020. V. 14. P. 35—41.
  8. Huber A. Air-coupled ultrasonic inspection of thermoplastic composite structures for aerospace vehicles / Proceedings of the 13th European Conference on Non-Destructive Testing. 2023.
  9. Schönheits M., Huber A., Gänswürger P. Air-coupled ultrasonic inspection with adaptive lamb wave control / Proceedings of the 16th International Conference on Informatics in Control, Automation and Robotics. 2019. P. 430—438.
  10. Szewieczek A., Hillger W., Bühling L., Ilse D. New developments and applications for air coupled ultrasonic imaging systems / Proceedings of the 10th International symposium on NDT in aerospace. 2018.
  11. Kachanov V.K., Sokolov I.V., Karavaev M.A. Development of an ultraacoustic mosaic wideband piezoelectric transducer for contactless testing of articles made of polymer composite materials // Meas. Tech. 2015. V. 58. P. 203—207. https://doi.org/10.1007/s11018-015-0686-2
  12. Panda R., Rajagopal P., Balasubramaniam K. Rapid guided wave inspection of complex stiffened composite structural components using non-contact air-coupled ultrasound // Composite Structures. 2018. V. 206. P. 247—260. https://doi.org/10.1016/j.compstruct.2018.08.024
  13. Gaal M., Caldeira R., Bartusch J., Schadow F., Vossing K., Kupnik M. Air-coupled ultrasonic ferroelectret receiver with additional bias voltage // IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control. 2019. V. 66. Is. 10. P. 1600—1605.
  14. Grager J., Kotschate D., Gamper J., Gaal M., Pinkert K., Mooshofer H., Goldammer M., Grosse C. Advances in air-coupled ultrasonic testing combining an optical microphone with novel transmitter concepts / Proceedings of the 12th European conference on Non-Destructive Testing. 2018.
  15. Schmid S., Dürrmeier F., Grosse C. Spatial and temporal deep learning in air-coupled ultrasonic testing for enabling NDE 4.0 // Journal of Nondestructive Evaluation. 2023. V. 42. https://doi.org/10.1007/s10921-023-00993-3
  16. Kachanov V.K., Sokolov I.V., Karavaev M.A., Minaev D.V. Developing methods and devices for ultrasonic contactless shadow testing of large-sized products made of polymer composite materials // Defectoskopiya. 2023. No. 1. P. 3—13.
  17. Kachanov V.K., Sokolov I.V., Karavaev M.A., Kontsov R.V. Selecting optimum parameters of ultrasonic noncontact shadow method for testing products made of polymer composite materials // Defectoskopiya. 2020. No. 10. P. 60—70.
  18. Ul’trazvkovye preobrazovateli dlya nerazrushayushchego kontrolya (Ultrasonic Transducers for Nondestructive Testing) / Ermolov I.N. Ed. Moscow: Mashinostroenie, 1986.
  19. Krautkramer J., Krautkramer H. Werkstoffprufung mit ultraschall. Berlin: Springer, 1986. Translated under the title Ultrazvukovoi kontrol’ materialov / Spravochnik. Moscow: Metallurgiya, 1991.
  20. Wang X., Gong X., Li C., Wu R., Chen Z., Wu H., Zhang D., Cao X. Low insertion loss air-coupled ultrasonic transducer with parallel laminated piezoelectric structure // AIP Advances. 2020. V. 10. Is. 10.
  21. Chen J., Wang X., Yang X., Zhang L., Wu H. Application of air-coupled ultrasonic nondestructive testing in the measurement of elastic modulus of materials // Applied Sciences. 2021. V. 11.
  22. Bodi A., Fuchs M., Steinhausen R., Jongmanns M. New technologies for air-coupled ultrasonic inspection / Proceedings of the 13th European conference on non-destructive testing. 2023.
  23. Modeling Speaker Drivers in COMSOL Multiphysics. Supplement A: Equations. URL: https://www.comsol.com/support/learning-center/article/supplement-a-equations-76561/202 Accessed March 6, 2025.
  24. Aronov B.S. Elektromekhanicheskie preobrazovateli iz p’ezoelektricheskoj keramiki (Electromechanical transducers made of piezoelectric ceramics). Leningrad: Energoatomizdat, 1990.
  25. Rybyanets A.N., Nasedkin A.V., Shcherbinin S.A., Petrova E.I., Shvetsova N.A., Shvetsov I.A., Lugovaya M.A. The finite-element simulation of low-frequency bimorph transducers for the diagnostics and activation of oil wells // Acoust. Phys. 2017. V. 63. P. 737—743. https://doi.org/10.1134/S1063771017060124
  26. Teplykh A.A., Zaitsev B.D., Shikhabudinov А.М., Borodina I.A. Refinement of the material constants of PZT-19 piezoceramics using an acoustic resonator in the form of a disk // Uchen. zap. fiz. fak. MGU. 2017. No. 5.
  27. COMSOL. Introduction to the Acoustics Module. https://doc.comsol.com/5.6/doc/com.comsol.help.aco/IntroductionToAcousticsModule.pdf. Accessed March 6, 2025.
  28. COMSOL. Acoustics Module User’s Guide. https://doc.comsol.com/5.6/doc/com.comsol.help.aco/AcousticsModuleUsersGuide.pdf. Accessed March 6, 2025.
  29. Vopilkin A.Kh. Calculation and design of broadband axisymmetric transducers of variable thickness // Defectoskopiya. 1987. No. 4. P. 41—50.
  30. Hutchins D.A., McIntosh J.S., Neild A., Billson D.R., Noble R.A. Radiated fields of capacitive micromachined ultrasonic transducers in air // J. Acoust. Soc. Am. 2003. V. 114. No. 3. P. 1435—1449. https://doi.org/10.1121/1.1604120
  31. Schadow F., Gaal M., Bartusch J., Dohse E., Köppe E. Focusing air-coupled ultrasonic transducers based on ferroelectrets / Proc. 19th WCNDT. 2016.
  32. Neild A., Hutchins D.A., Robertson T.J., Davis L.A.J., Billson D.R. The radiated fields of focussing air-coupled ultrasonic phased arrays // Ultrasonics. 2005. V. 43. P. 183—195. https://doi.org/10.1016/j.ultras.2004.04.006
  33. Kachanov V.K., Sokolov I.V., Konov M.M., Timofeev D.V., Sinitsyn A.A. Spatiotemporal characteristics of broadband ultrasonic transducers // Defectoskopiya. 2010. No. 10. P. 11—25.

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2. Fig. 1. Selecting the optimal distance between the transmitter and the receiver: a — diagram of the transmitter location relative to the receiver; b — near and far zones of a narrow-band transmitter in the air (1 — boundary of the near zone corresponding to the maximum amplitude of the emitted ultrasonic signal; 2 — extent of the near zone); c — acoustic pressure field of a narrow-band transmitter in the air (simulation).

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3. Fig. 2. The effect of the thickness of the matching foam layer on the amplitude of the signal received by the contactless PE: a — structural diagram of the experiment; b — dependence of the signal amplitude on the thickness of the matching layer.

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4. Fig. 3. Sketch of a contactless PEP.

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5. Fig. 4. A quarter of the three-dimensional geometry of the model with visualization of the finite element mesh: a — for calculation in the frequency domain; b — for calculation in the time domain.

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6. Fig. 5. Dependence of the length of the near zone zbl on the thickness of the second layer d2.

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7. Fig. 6. Mosaic contactless LF PET (without housing) with two matching layers with four PE of square cross-section 7×7 mm.

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8. Fig. 7. Dependence of the near-field zone extent zbl on the frequency f.

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9. Fig. 8. The CRP of a broadband (Δf = 30 kHz) composite non-contact PT in air using a broadband chirp signal (simulation): a — CRP in two-dimensional form; b — three-dimensional CRP.

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10. Fig. 9. Photograph (a) and installation diagram (b) for contactless ultrasonic shadow scanning of products.

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11. Fig. 10. Acoustic field on the axis of a contactless broadband transmitter.

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12. Fig. 11. Results of testing the product simulator: a — dв = dв.опт = 25 mm; b — dв = 50 mm.

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