Modeling and Study of Glued Wood Panel
Keywords:glued wooden panel, defects, resonance vibration, modulus of elasticity, coefficient of damping.
Widely used glued wooden panels have to meet quality requirements. Their mechanical properties are highly dependent on gluing quality. The paper presents the results of quality studies conducted according to an elaborated method, imitating gluing defects of panels. Glued oak wood panels were studied by the method of resonance vibrations in a special stand within 20 – 2000 Hz frequency range. Defects were imitated making incisions in the places of glue lines. Several defect variants were modeled – defect in the centre of panels, defect at the edge of panels and two defects – in the centre and at the edge. The change of panel amplitude-frequency characteristics was ascertained. It was found, that with increasing linear dimensions of defects, mean vibration amplitudes of panels decrease. It was obtained, that the modulus of elasticity along the grain comprise 12000 – 13000 MPa, while across the grain 933 – 1600 MPa, damping coefficients (tgδ) – 0.015 – 0.04. With increasing incision, the modulus of elasticity in the longitudinal direction practically did not change, meanwhile transversely they decreased down to 321 – 760 MPa, damping coefficients augmented up to 0.02 – 0.05. Critical incision lengths were ascertained under significant changes of transverse panel bend forms. When incision is at the edge, critical incision length comprises about 0.5 of the panel length, while when incision is in the centre or there are two incisions – about 0.3 of the panel length. It was found, that change peculiarities of the mentioned parameters characterize mechanical properties and the quality of panels.
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