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National Repository of Grey Literature 2 records found  Search took 0.02 seconds. 
Pevnost vybraných konstrukčních spojů s použitím modifikovaného dřeva buku
 Valíčková, Lenka
The thesis focuses on the influence of selected European beech wood modifications (Fagus sylvatica L.), i.e. acetylation and thermal modification at 200 °C and 220 °C, on the strength of structural joints used in the furniture industry. Based on the literature research, three types of structural joints were selected, which were subsequently tested. The strength of the glued joint was tested according to ČSN EN 205, withdrawal capacity of a screw according to ČSN 49 0135 and the corner screw joint. The results of the measurements were statistically evaluated using a one-way ANOVA and the measured groups were compared to each other. The results demonstrate that all types of modification lead to a decrease in mechanical strength. Wood acetylation lead to a statistically significant differences in the values for the glued joint. The thermal modification at 200 °C achieved statistically significant differences in the withdrawal capacity of a screw. The biggest drop in values came after a thermal modification at 220 °C, which were statistically significantly different when testing all selected joints. In the case of acetylation and heat modification up to 200 °C, it is not possible to unequivocally identify a method that showed significantly better results across all tests. Both metods of modyfying wood showed possibilities of use in furniture design. However, a decrease in the mechanical properties ofthe modifies material muse be taken into account when determining the dimensions of the structure.
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Vliv chemické modifikace na rozměrovou stabilitu ohnutých dílců z masivního bukového dřeva
 Jacko, Ondřej
This thesis deals with the effect of chemical modification on dimensional stability of bent solid beech wood samples. Acetylation at 120 ° C and steaming in saturated steam at 90 °C were chosen as chemical modification. The properties examined included dimensional stability and moisture absorption of the bent specimens. Standard samples produced were used to determine properties such as bulk swelling, moisture absorption and density. These properties were determined after modification, after long-term storage in a warehouse and after storage in an climate chamber at 20 ° C and 80% relative humidity. The air conditioning was followed by drying the bent samples to 0% humidity, which showed the dimensional stability of the bent shape. The best weight percent gain (WPG) values were achieved by standard and bent acetylated samples, the AC 2 group, which also had the most reduced RVD. The WPG for this group was 23.31%. Due to the highest WPG value, this group also achieved the best values in detecting anti-swelling efficiency (ASE), ie 81.99%. The best dimensional stability was achieved by steaming the specimens in saturated steam
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