Vobolis, J. and Albrektas, D. 2007. Analysis of Wood Peculiarities by Resonant Vibration Method. Baltic Forestry 13 (1): 109-115
Most wood products meet dynamic loads. Evaluation of mechanical properties of wood in dynamic mode allows forecasting wood assortment behaviour in dynamic loads zone. The article discusses modulus of elasticity research methodology and equipment for leafy and conifer (oak and spruce) rectangular wood plates (oak - 340×340×14 mm and 400×300×14 mm, spruce - 300×280×30 mm and 300×265×30 mm), glued-up panels (oak - 500×500×30 mm and 700×700×30 mm, spruce - 400×400×14 mm) and scantlings (oak - 670×60×30 mm, spruce - 400×40×14 mm).
Cross-resonant vibrations method was employed for wood assortment analysis. Resonant frequencies and bend forms (modes) were evaluated. It was illustrated that through different along and across mechanical properties of wood fiber vibration of such products to the above-mentioned directions are parallel to vibration of beam-formed body.
Applying theoretical calculations for beam-formed body, oak wood modulus of elasticity was estimated across (Ep= 900 - 2000 MPa) and along (El = 8000 - 14000 MPa) fiber. For spruce wood, respectively, (Ep= 140 - 500 MPa) and (El = 7500 - 14000 MPa).
Suggested methodology and equipment can be successfully applied to analysis and quality evaluation (assortment, hunt for defects, etc.) of other products, analogical to natural wood in terms of fiber direction.
Key words: wood plate, glued-up panel, scantlings, resonance vibrations, modulus of elasticity