Abstract
Air-coupled ultrasound (ACU) is used in through transmission to detect delamination, rot, and cracks in wood without altering the structure permanently. Novel ferroelectret transducers with a high signal-to-noise ratio enable high-precision structure recognition. Transducers made of cellular polypropylene are quite suitable for ACU testing due to their extremely low Young’s modulus and low density resulting in a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. Thus, structures with great dimensions, with a thickness of up to 300 mm and material densities below 500 kg/m3, can be inspected. Promising results were obtained under laboratory conditions with frequencies ranging from 90 to 200 kHz. The advantage of ACU transducers is that they do not require contact to the sample; they are accurate and cost-effective. Ultrasonic quality assurance for wood is an important avenue to increase the acceptance of wooden structures and toward sustainability in civil engineering in general.
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References
Buckley J (2000) Air-coupled ultrasound—a millennial review. In: Paper presented at the 15th world conference on NDT, Rome
Bucur V (2003) Nondestructive characterization and imaging of wood. Wood Science, Springer, Berlin
Bucur V (2005) Acoustics of wood. Springer series in wood science. Springer, Berlin
Bucur V (2011) Delamination in wood, wood products and wood-based composites, 1st edn. Springer, Netherlands
Chimenti DE (2014) Review of air-coupled ultrasonic materials characterization. Ultrasonics 54:1804–1816
Döring J, Bovtun V, Bartusch J, Erhard A, Kreutzbruck M, Yakymenko Y (2010) Nonlinear electromechanical response of the ferroelectret ultrasonic transducers. Appl Phys A Mater Sci Process 100:479–485
Döring J, Bovtun V, Gaal M, Bartusch J, Erhard A, Kreutzbruck M, Yakymenko Y (2012) Piezoelectric and electrostrictive effects in ferroelectret ultrasonic transducers. J Appl Phys. https://doi.org/10.1063/1.4759052
Fang Y, Lin L, Feng H, Lu Z, Emms GW (2017) Review of the use of air-coupled ultrasonic technologies for nondestructive testing of wood and wood products. Comput Electron Agric 137:79–87
Gaal M, Bartusch J, Dohse E, Schadow F, Köppe E (2016a) Focusing of ferroelectret air-coupled ultrasound transducers. AIP Conf Proc 1706:080001. https://doi.org/10.1063/1.4940533
Gaal M, Bovtun V, Stark W, Erhard A, Yakymenko Y, Kreutzbruck M (2016b) Viscoelastic properties of cellular polypropylene ferroelectrets. J Appl Phys 119:125101. https://doi.org/10.1063/1.4944798
Gaal M, Caldeira R, Bartusch J, Schadow F, Vössing K, Kupnik M (2018) Air-coupled ultrasonic ferroelectret receiver with additional bias voltage. IEEE Trans Ultrason Ferroelectr Freq Control (under review)
Hasenstab A (2006) Integritätsprüfung von Holz mit dem zerstörungsfreien Ultraschallechoverfahren. (Integrity testing of wood with the nondestructive ultrasonic echo technique). Dissertation, Technische Universität Berlin
Hilbers U, Neuenschwander J, Hasener J, Sanabria SJ, Niemz P, Thoemen H (2012a) Observation of interference effects in air-coupled ultrasonic inspection of wood-based panels. Wood Sci Technol 46:979–990
Hilbers U, Thoemen H, Hasener J, Frühwald A (2012b) Effects of panel density and particle type on the ultrasonic transmission through wood-based panels. Wood Sci Technol 46:685–698
Hughes M (2015) Wood composites. In: Ansell MP (ed) Woodhead publishing series in composites science and engineering, vol 2. Elsevier, Amsterdam, pp 69–89
Kunkle J, Vun RY, Eischeild T, Langron M, Bhardwaj N, Bhardwaj M (2006) Phenomenal advancements in transducers and piezoelectric composites for non-contact ultrasound and other applications. In: Paper presented at the european conference on non-destructive testing (ECNDT). Germany, Berlin
Marhenke T, Neuenschwander J, Furrer R, Twiefel J, Hasener J, Niemz P, Sanabria SJ (2018) Modeling of delamination detection utilizing air-coupled ultrasound in wood-based composites. NDT E Int 99:1–12
Nowak TP, Jasienko J, Hamrol-Bielecka K (2016) In situ assessment of structural timber using the resistance drilling method—evaluation of usefulness. Constr Build Mater 102:403–415
Paajanen M, Lekkala J, Kirjavainen K (2000) Electromechanical film (EMFi)—a new multipurpose electret material. Sensors Actuators A Phys 84:95–102
Riggio M, Sandak J, Franke S (2015) Application of imaging techniques for detection of defects, damage and decay in timber structures on-site. Constr Build Mater 101:1241–1252
Ross RJ, Pellerin RF (2002) Nondestructive evaluation of wood. Forest Products Society, Madison
Sanabria SJ (2012) Air-coupled ultrasound propagation and novel non-destructive bonding quality assessment of timber composites. Dissertation, ETH
Sanabria SJ, Furrer R, Neuenschwander J, Niemz P, Sennhauser U (2013) Novel slanted incidence air-coupled ultrasound method for delamination assessment in individual bonding planes of structural multi-layered glued timber laminates. Ultrasonics 53:1309–1324
Sessler GM, Hillenbrand J (1999) Electromechanical response of cellular electret films. Appl Phys Lett 75:3405–3407
Solodov I, Pfleiderer K, Busse G (2004) Nondestructive characterization of wood by monitoring of local elastic anisotropy and dynamic nonlinearity. Holzforschung 58:504–510
Vössing K, Niederleithinger E (2018) Nondestructive assessment and imaging methods for internal inspection of timber. A review. Holzforschung 72:467–476
Wegener M et al (2004) Controlled inflation of voids in cellular polymer ferroelectrets: optimizing electromechanical transducer properties. Appl Phys Lett 84:392–394
White RH, Ross RJ (2014) Wood and timber condition assessment manual, vol 2. United States Department of Agriculture, Washington
Zhang X, Hillenbrand J, Sessler GM (2004) Piezoelectric d33 coefficient of cellular polypropylene subjected to expansion by pressure treatment. Appl Phys Lett 85:1226–1228
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The research work was subsidized by the Cusanuswerk, Episcopal Study Sponsorship.
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Vössing, K.J., Gaal, M. & Niederleithinger, E. Air-coupled ferroelectret ultrasonic transducers for nondestructive testing of wood-based materials. Wood Sci Technol 52, 1527–1538 (2018). https://doi.org/10.1007/s00226-018-1052-8
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DOI: https://doi.org/10.1007/s00226-018-1052-8