Abstract
Glued timber products are widely used in construction; therefore, it is necessary to develop non-destructive bonding quality assessment methods for long-term structural health monitoring. Air-coupled ultrasound (ACU) inspection is a novel technique, with phenomenal improvements in reproducibility compared to traditional contact ultrasonics, unlimited scanning possibilities, and a high potential for delamination detection in wood products. As part of an ongoing project, glued timber samples of 10 mm thickness with artificial glue line defects were inspected. A normal through-transmission set-up with 120 kHz transducers allowed for successful and accurate imaging of the geometry of glued and non-glued areas in all inspected objects. The influence of wood heterogeneity and the reproducibility of ACU amplitude measurements were analysed in detail, identifying the main sources of variation. Future work is planned for the inspection of more complex glued timber objects.
Similar content being viewed by others
References
Aicher S, Dill-Langer G, Ringger T (2002) Non-destructive detection of longitudinal cracks in glulam beams. Otto Graf J 13:165–181
Biernacki JM, Beall FC (1996) Acoustic monitoring of cold-setting adhesive curing in wood laminates. Int J Adhes Adhes 16(3):165–172
Brekhovskikh LM (1980) Waves in layered media. Academic Press, New York
Bucur V (2002) Propagation and polarization of ultrasonic waves in wood. In: Proc. of the 11th international symposium on nondestructive characterization of materials, Berlin, Germany, pp 55–60
Bucur V (2006) Acoustics of wood. Springer, Berlin
Bucur V, Bohnke I (1994) Factors affecting ultrasonic measurements in solid wood. Ultrasonics 32(5):385–390
Choi MY, Park JH, Kim WT, Kang KS (2008) Detection of delamination defect inside timber by sonic IR. In: Proc. of the society of photo-optical instrumentation engineers (SPIE), Orlando, FL, USA, pp U306–U309
Deutsch V, Platte M, Vogt M, Verein Deutscher Ingenieure (1997) Ultraschallprüfung Grundlagen und industrielle Anwendungen. Springer, Berlin
Dill-Langer G, Bernauer W, Aicher S (2005a) Inspection of glue-lines of glued-laminated timber by means of ultrasonic testing. In: Proc. of the 14th international symposium on nondestructive testing of wood, Eberswalde, Germany, pp 49–60
Dill-Langer G, Aicher S, Bernauer W (2005b) Reflection measurements at timber glue-lines by means of ultrasound shear waves. Otto Graf J 16:273–283
Dunky M, Niemz P (2002) Holzwerkstoffe und Leime: Technologie und Einflussfaktoren. Springer, Berlin
EN 14080:2005 Timber structures—glued laminated timber—requirements
EN 391:2001 Glued laminated timber—delamination test of glue lines
Feeney FE, Chivers RC, Evertsen JA, Keating J (1997) The influence of inhomogeneity on the propagation of ultrasound in wood. In: Proc. of the 17th ultrasonics international conference (UI 97), Delft, Netherlands, pp 449–453
Gan TH, Hutchins DA, Green RJ, Andrews MK, Harris PD (2005) Noncontact, high-resolution ultrasonic imaging of wood samples using coded chirp waveforms. IEEE T Ultrason Ferr 52(2):280–288
Gattiker F, Umbrecht F, Neuenschwander J, Sennhauser U, Hierold C (2007) Novel ultrasound read-out for a wireless implantable passive strain sensor (WIPSS). Sensor Actuat A-Phys 145(Sp. Iss.):291–298
Gudra T (2008) Ultrasounds in gas media: generation, transmission, applications (review paper). Arch Acoust 33(4):581–592
Hasenstab A (2006) Integritaetspruefung von Holz mit dem zerstoerungsfreien Ultraschallechoverfahren. Dissertation, Technische Universitaet Berlin
Hasenstab A, Krause M, Hillger W, Buehling L, Ilse D, Hillemeier B, Rieck C (2005) Luftultraschall und Ultraschall-Echo-Technik an Holz. In: Proc. of the German society for nondestructive testing (DGZfP), Rostock, Germany
Hu LJ, Gagnon S (2007) X-Ray-based scanning technique for non-destructive evaluation of finger-joint strength. In: Proc. of the 15th international symposium on NDT of wood, Deluth, MN, USA
Kabir MF, Schmoldt DL, Schafer ME (2002) Time domain ultrasonic signal characterization for defects in thin unsurfaced hardwood lumber. Wood Fiber Sci 34(1):165–182
Kunkle J, Vun RY, Eischeild T, Langron M, Bhardwaj N, Bhardwaj MC (2006) Phenomenal advancements in transducers and piezoelectric composites for non-contact ultrasound and other applications. In: Proc. of the European conference on non-destructive testing (ECNDT), Berlin, Germany
Maeva E, Severina I, Bondarenko S, Chapman G, O’Neill B, Severin F, Maev RG (2004) Acoustical methods for the investigation of adhesively bonded structures: a review. Can J Phys 82(12):981–1025
Neuenschwander J, Niemz P, Kucera LJ (1997) Studies for visualizing wood defects using ultrasonic techniques in reflection and transmission mode. Holz Roh- Werkst 55(5):339–340
Niemz P, Sander D (1990) Prozessmesstechnik in der Holzindustrie. VEB Fachbuchverlag, Leipzig
Rangarajan R, Krishnamurthy CV, Balasubramaniam K (2008) Ultrasonic imaging using a computed point spread function. IEEE T Ultrason Ferr 55(2):451–464
Schmerr LW, Song S-J (2007) Ultrasonic nondestructive evaluation systems models and measurements. Springer, New York
Siddiolo AM, D’Acquisto L, Maeva AR, Maev RG (2007) Wooden panel paintings investigation: an air-coupled ultrasonic imaging approach. IEEE T Ultrason Ferr 54(4):836–846
Solodov I, Pfleiderer K, Busse G (2004) Nondestructive characterization of wood by monitoring of local elastic anisotropy and dynamic nonlinearity. Holzforschung 58(5):504–510
Stoessel R (2004) Air-coupled ultrasound inspection as a new non-destructive testing tool for quality assurance. Dissertation, Universitaet Stuttgart
Vun RY, Wu QL, Bhardwaj MC, Stead G (2003) Ultrasonic characterization of structural properties of oriented strandboard: a comparison of direct-contact and non-contact methods. Wood Fiber Sci 35(3):381–396
Acknowledgments
This research has been supported by the Swiss National Science Foundation under contract 200021-115920. The authors acknowledge the work of Oliver Tolar and Fabian Binkert for the analysis of optical images and processing of ultrasonic data.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Sanabria, S.J., Mueller, C., Neuenschwander, J. et al. Air-coupled ultrasound as an accurate and reproducible method for bonding assessment of glued timber. Wood Sci Technol 45, 645–659 (2011). https://doi.org/10.1007/s00226-010-0357-z
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00226-010-0357-z