An Evaluation of Modulus of Elasticity, Dimensional Stability and Bonding Strength of Bonded Heat-Treated Wood
| Autor: | Darius Albrektas, Povilas Navickas |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Drvna industrija Volume 68 Issue 2 |
| ISSN: | 1847-1153 0012-6772 |
| Popis: | In this study, the effects of heating on the mechanical and sorption properties of pine and spruce wood were investigated. The study was carried out using wood heated in laboratory. Specimens were divided into the following three groups: specimens of one group were not exposed to heating, whereas specimens of two other groups were subjected to heating at the temperature of 190 °C and 215 °C, in the air under atmospheric pressure. Specimens were then bonded together using a cold press and four different systems of not heated and heated (at different temperatures) samples were formed: two not heated samples and two samples heated at different temperatures. After that, newly formed systems were moistened and dried in a climatic chamber and measurements of dimensional changes were carried out. Then the mechanical properties were observed again using two different methods - method of transverse vibrations and method of three point static bending. A positive and strong correlation coefficient was determined between static and dynamic MOE values, however, dynamically determined MOE was up to 16 % higher. None of the bonded specimens became loosened during soaking and drying, which means that wood, heated at the different temperatures, could be bonded together thereby obtaining a system of heat-treated wood that may have better mechanical or sorption properties than solid wood. U radu je prikazano istraživanje utjecaja toplinske obrade drva na mehanička i sorpcijska svojstva borovine i smrekovine. Istraživanje je provedeno na drvu koje je toplinski obrađeno u laboratoriju. Uzorci su podijeljeni u sljedeće tri skupine: uzorci koji nisu bili izloženi toplinskoj obradi, uzorci toplinski obrađeni u zraku – pri atmosferskom tlaku i temperaturi 190 °C, te na uzorke obrađene na temperaturi 215 °C. Zatim su uzorci slijepljeni u hladnoj preši tako da su izrađena četiri slijepljena spoja: od uzoraka toplinski neobrađenog drva i toplinski obrađenog drva pri 190 °C, od uzoraka toplinski neobrađenog drva i toplinski obrađenog drva pri 215 °C, od dva uzorka toplinski neobrađenog drva i od uzoraka drva toplinski obrađenoga pri dvije različite temperature. Nakon toga novonastali su spojevi navlaženi i osušeni u klimatskoj komori te su provedena mjerenja dimenzijskih promjena. Zatim su dvjema različitim metodama – metodom transverzalnih vibracija i metodom trotočkastoga statičkog savijanja – ispitana njihova mehanička svojstva. Utvrđen je pozitivan i visok koeficijent korelacije između vrijednosti statičkoga i dinamičkog modula elastičnosti, pri čemu je dinamički modul elastičnosti bio do 16 % veći od statičkoga. Nijedan od slijepljenih spojeva pri navlaživanju i sušenju nije izgubio čvrstoću, što znači da se drvo toplinski obrađeno pri različitim temperaturama može lijepiti. Tako dobiven slijepljeni spoj toplinski obrađenog drva može imati bolja mehanička ili sorpcijska svojstva od masivnog drva. |
| Databáze: | OpenAIRE |
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