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Stanovení mechanických vlastností konstrukčního lepeného hranolu z bukového dřeva
Kománek, Martin
The aim of this thesis is to experimentally assess the wood of the European beech (Fagus sylvatica, L.) with regard to the possibilities of its use in the building industry. For this purpose, were made test samples in the form of solid and glued beams measuring 100 x 100 x 1000 mm. Half of the beams were soaked for thirty days in the water for w highter than MH, the other half was conditioned for long time under conditions equilibrium wood moisture stabilized at a humidity of = 12 %. The wooden beams were subjected to a symmetrical 3-point and 4-point bending test according to ČSN EN 408+A1 (2012). Examine mechanical characteristic were a strength limit of a bending, an elasticity modulus of the bending and a shear elastic modulus determined also from the bending test. According to our experiment, the shear moduli of elasticity with high scatter values and therefore statistically insignificant. Flexural modulus values were obtained for massive with w = 12%, 7 858 MPa, for massive with w highter than MH prisms 3 724 MPa, for prisms glued with polyurethane adhesive Lear D4 with w = 12%, 7 693 MPa and for prisms bonded with phenol formaldehyde adhesive Lignofen G/3/D with w = 12%, 7 853 MPa. The strength of the beams were delivered for massive with w = 12%, 79 MPa, for massive w highter than MH, 41 MPa, for beams glued with polyurethane adhesives Lear D4 with w = 12%, 83 MPa and for bonded phenol formaldehyde glue with w = 12%, 73 MPa. The above values were influenced by many factors such as density, moisture, wood defects, or the quality of prisms gluing.
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