18. Resonant vibration-based evaluation of wood drying defects

J. Vobolis1, D. Albrektas2

Kaunas University of Technology, Kaunas, Lithuania

1Corresponding author

E-mail: 1jonas.vobolis@ktu.lt, 2darius.albrektas@ktu.lt

(Received 11 January 2013; accepted 7 June 2013)

Abstract. Mechanical properties of many wood products are assessed by treating them as distributed parameter systems, i.e. as beams, panels and the like. Internal defects detected in specimens, such as decay, knags, cracks and etc., determine the extensive distribution of measured parameters. It becomes especially relevant to evaluate the quality of dried wood assortments, since wood develops cracks as a result of stresses that occur during the drying process. Tests were performed in order to detect cracks in dried wood assortments. When measuring resonant vibrations of beam-shaped specimens, it was established that present cracks contribute to the distortion of the amplitude-frequency characteristic of the specimen. Cracked specimens vibrate as the system of concentrated masses and the amplitude-frequency characteristic of the first mode already has several resonant frequencies. Changes in amplitude-frequency characteristics were assessed during the simulation of cracks and when wood specimens undergo drying under strict regimes.

Keywords: resonant vibrations, wood drying defects, amplitude-frequency characteristics, modelling of drying defects.

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Cite this article

Vobolis J., Albrektas D. Resonant vibration-based evaluation of wood drying defects. Journal of Measurements in Engineering, Vol. 1, Issue 2, 2013, p. 113‑120.

 

Journal of Measurements in Engineering. June 2013, Volume 1, Issue 2
© Vibroengineering. ISSN Print 2335-2124, ISSN Online 2424-4635, Kaunas, Lithuania