Spooni suuna asetuse muutmisest tingitud mõju vineeri tugevusomadustele
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Kuupäev
2024
Kättesaadavus
10.09.2024
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Käesoleva magistritöö eesmärkideks on valmistada ja katsetada erinevate spoonisuuna kombinatsioonidega katseplaate. Uuritavateks parameetriteks on pikikiudu ja ristikiudu paindetugevus ja paindeelastsusmoodul ning äärmise ja keskmise spoonikihi nihketugevus. Eesti Maaülikooli puidutöökojas valmistatakse erineva spoonipaigutusega seitsme– ja viiekihilised katseplaadid vastavalt Euroopa Standarditele. Spoonilehti lõigatakse kolme eri suunaga 0°/90°, 22,5°/67,5°/112,5°/157,5° ning 45°/135°. Vastavalt plaatide omapärale komplekteeritakse spoonipaketid, mis kaetakse fenoolformaldehüüd liimiga ning pressitakse. Valminud plaatidest lõigatakse katsekehad, mida katsetatakse Eesti Maaülikooli puidulaboris vastavalt Euroopa Standarditele.
Pikikiudu paindekatsete ning nihkekatsete puhul on suurimad tulemused plaatidel, mille spoonisuunad jäävad vahemikku 0°-22,5°. Ristikiudu paindekatsete puhul on suurimad tulemused plaatidel, mille spoonisuunad on 67,5°-90°.
Seitsme- ja viiekihiliste samasuguste spooninihutusega plaaditüüpide puhul keskmine spoonisuund ei mõjuta märgatavalt painde- ega nihkeomadusi. Viiekihiliste plaatide puhul, kus teine ja neljas spoonikiht on peegeldatud ning keskmine kiht on 90°, mõjutab keskmine spoonikiht painde- ja nihkeomadusi.
The aims this Master’s thesis are to prepare and test plywood plates with various veneer direction combinations. The parameters to be examined are the bending strength, the modulus of elasticity of the longitudinal and cross-directional wood fibers and the shear strength of the outer and middle veneer layers. Test panels are produced in the wood workshop of the Estonian University of Life Sciences. The panels with seven- and five-layers, each with a different veneer placements are manufactured in compliance with the European Standards. The veneer sheets are cut using three different methods: 0°/90°, 22.5°/67.5°/112.5°/157.5° and 45°/135°. Veneer packets are assembled, covered in phenol formaldehyde adhesive, and pressed in accordance with the unique feature of the panels. The test specimens that are cut from the pressed panels are examined in the wood laboratory of the Estonian University of Life Sciences in accordance with the European Standards. In the case of longitudinal bending tests and shear tests, higher results are obtained for panels which veneer directions are between 0°-22.5°. Panels which veneer directions are between 67.5°-90° gave higher results in cross-bending testing. The average veneer direction does not significantly affect bending or shear properties for seven- and five-layer panel types with the same veneer displacement. The central veneer layer in five-layer panels influence the bonding and shear qualities only in the panels, which middle veneer layer is 90° and the second and fourth veneer layers are mirrored.
The aims this Master’s thesis are to prepare and test plywood plates with various veneer direction combinations. The parameters to be examined are the bending strength, the modulus of elasticity of the longitudinal and cross-directional wood fibers and the shear strength of the outer and middle veneer layers. Test panels are produced in the wood workshop of the Estonian University of Life Sciences. The panels with seven- and five-layers, each with a different veneer placements are manufactured in compliance with the European Standards. The veneer sheets are cut using three different methods: 0°/90°, 22.5°/67.5°/112.5°/157.5° and 45°/135°. Veneer packets are assembled, covered in phenol formaldehyde adhesive, and pressed in accordance with the unique feature of the panels. The test specimens that are cut from the pressed panels are examined in the wood laboratory of the Estonian University of Life Sciences in accordance with the European Standards. In the case of longitudinal bending tests and shear tests, higher results are obtained for panels which veneer directions are between 0°-22.5°. Panels which veneer directions are between 67.5°-90° gave higher results in cross-bending testing. The average veneer direction does not significantly affect bending or shear properties for seven- and five-layer panel types with the same veneer displacement. The central veneer layer in five-layer panels influence the bonding and shear qualities only in the panels, which middle veneer layer is 90° and the second and fourth veneer layers are mirrored.
Kirjeldus
Magistritöö
Metsatööstuse õppekaval
Märksõnad
magistritööd, vineer, spooni paigutus, spooni suund, spooni nurk, LVL