WOOD RESEARCH Volume 62, Number 4, 2017
Vladimir Fedyukov, Ekaterina Saldaeva, and Maria Chernova

Different ways of elastic modulus comparative study to predict resonant properties of standing spruce wood

Resonant method of determining modulus of elasticity and shift and decrement of fluctuations’ operates in Russia to determine elastic-viscous properties of wood (GOST 16483.31-197474). The method is destroying and demanding much time and expenses for manufacturing pre-production models in the form of rectangular bar sized 20×20×300 mm, which requires tree cutting down, severing, sawing, etc.; as a consequence, it has not found wide implementation in the practice of research and, especially, selection of qualitative material for musical instruments manufacturing. The work objective is to conduct basic research on revealing a more effective and precise non-destructive method for identifying Young’s dynamic modulus of elasticity as a basic criterion of standing spruce-tree resonant wood quality with the aim of its selection at an early age and creation of perspective object for woodworking with reference to musical instruments manufacture.

WOOD RESEARCH Volume 63, Number 4, 2018
Limin Peng, Meihong Liu, Dong Wang, and Boqi Song

Sound absorption properties of wooden perforated plates

Wooden perforated plates are used to control noise and optimize the indoor sound environment. In the paper, the effects of structure factors on the sound absorption properties, such as the absorption peak, resonant frequencies, and frequency bandwidth, were analyzed using the impedance tube transfer function method and SAS (Data analysis software) significant analysis. Experimental results showed that with the thickness of the medium density fiberboard (MDF) perforated plate increasing from 10 to 20 mm, the resonance absorption frequency shifts to the lower frequency. The depth of hole increased, the absorption peak reinforced. With the pore size increased, the resonance absorption frequency reduced and meanwhile the resonance peak absorption coefficient shrunk. The resonance frequency moves toward the high frequency direction and the sound absorption coefficient decreased when the perforation rate was increased from 3.14% to 7.07%. After increasing the air gap thickness from 25 to 100 mm, the resonance absorption frequency reduced and the sound absorption bandwidth remained relatively constant as the acoustic impedance of the MDF perforated plate did not vary in spite of the variation in the air gap thickness. But the absorption coefficient decreased. This paper may provide a certain theoretical basis for wooden perforated plate design and research.