The sound absorption coefficients of wood and wood boards for five eucalypt species (Eucalyptus urophylla, Euca-lyptus urophylla E. grandis, Eucalyptus urophylla E. tereticornis, Eucalyptus urophylla E. camaldulensis ...The sound absorption coefficients of wood and wood boards for five eucalypt species (Eucalyptus urophylla, Euca-lyptus urophylla E. grandis, Eucalyptus urophylla E. tereticornis, Eucalyptus urophylla E. camaldulensis and Eucalyptus cloeziana) that were collected from plantation in Dongmen Forestry Center of Guangxi Province, China were tested with stand-ing wave method and their sound absorption properties were also compared. The results showed that the sound absorption co-efficients of the five eucalypt wood species did not change evidently below 1000 Hz, but above 1000 Hz their sound absorption coefficients increased with the increasing frequency. The difference in sound absorption coefficient among five species of eucalypt wood is not evident at the tested frequency range (200-2000 Hz), but the sound absorption property of Eucalyptus urophylla at low frequency is better than that of other four species. The sound absorption coefficient of the tangential-sawn board is higher than that of the radial-sawn board. The sound absorption property of eucalypt wood of 0.5 cm in thickness is much better than that of 1.0 cm in thickness. It is concluded that wood sound absorption properties of eucalypts are affected by their board thickness and the type of sawn timber within the testing frequency, but the variance of wood sound absorption property among the five tested species is not significant.展开更多
The effectiveness of pilodyn was tested in evaluating wood basic density, outer wood density, heartwood density, and modulus of elasticity （MoE） at 22 four-year-old eucalyptus clones in Guangxi, China. Results indic...The effectiveness of pilodyn was tested in evaluating wood basic density, outer wood density, heartwood density, and modulus of elasticity （MoE） at 22 four-year-old eucalyptus clones in Guangxi, China. Results indicated that the mean value ranged from 9.44 to 15.41 mm for Pilodyn penetration, 0.3514 to 0.4913 g.cm^-3 for wood basic density, and 3.94 to 7.53 Giga Pascal （GPa） for MoE, respectively. There were significant differences （1% level） in pilodyn penetration between different treatments, different directions and among the clones. Generally strongly negative correlations were found between pilodyn penetration and wood properties, and the coefficients ranged from -0,433 to -0,755. Our results, together with other studies, suggest that the use of pilodyn for assessing wood density and MoE was confirmed as a possibility.展开更多
This study was undertaken to determine the bending strength properties of off-cut Yellow Meranti wood by applying the finger jointed techniques. The finger orientations that were used in this study are vertical and ho...This study was undertaken to determine the bending strength properties of off-cut Yellow Meranti wood by applying the finger jointed techniques. The finger orientations that were used in this study are vertical and horizontal finger orientation. Specimens were bonded with PVAc （polyvinyl acetate）. The bending strength properties were determined by the three point and four point bending test method. The results show that vertical finger orientation has the higher mean of modulus of rupture and the modulus of elasticity value of 24.49 MPa （28.91 MPa） and 8,814 MPa （11,668 MPa） respectively. However, the tested specimen properties did not meet the minimum strength of the solid （control） specimens.展开更多
Collapse-type shrinkage is one of highly refractory drying defects inlow-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD),microfibril angle (MFA), double fibre cell wall th...Collapse-type shrinkage is one of highly refractory drying defects inlow-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD),microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP),unit cell wall shrinkage, total shrinkage and residual collapse, which are associated withcollapse-type shrinkage characteristics, were investigated by using simple regression method forthree species of collapse-susceptible Eucalyptus urophyll,, E. grandis and E. urophyllaxE.grandis,planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that:unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strongpositive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA;total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but notable to be predicted ideally by any examined factors alone owing to lower R^2 value (R^2≤0.5712);residual collapse was negatively correlated with BD and DWT, linearly positively correlated withMFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used assingle factor (R^2≥ 0.9412) to predicate unit cell wall shrinkage and RP is the relatively soundindicator for predicting residual collapse展开更多
The research method in this paper is based on the standard of American Society for Testing andMaterials (ASTM). Planing and sanding are selected to study the machining properties of E. urophylla × E.grandis plant...The research method in this paper is based on the standard of American Society for Testing andMaterials (ASTM). Planing and sanding are selected to study the machining properties of E. urophylla × E.grandis plantation wood. Moreover, the reasons for machining defects are analyzed. The results show E.urophylla × E. grandis planted in south China is a good species with a great potential for solid woodutilization.展开更多
In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to c...In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to conventional methods and the national standards. The effects of variances in cell wall thickness of wood fibre and vessel, and diameter of the cell lumen as well as the tissue ratio on the quality of plywood veneer were analysed. The results show that： 1） There is a great difference in fibre cell wall thickness and diameter of the cell lumen between early wood and late wood of Eucalyptus delegatensis. 2） E. obliqua has a high wood fibre tissue ratio and the thickest fibre cell wall, but the difference inthe fibre cell wall thickness between early wood and late wood is the smallest. 3） The wood fibre tissue ratio of E. regnans is smaller than that of E. obliqua, and its wood fibre cell wall isthe thinnest and there is only a very small difference in fibre cell wall thickness between early wood and late wood. The difference inthe diameter of wood fibre cell lumen among early wood, transition area and late wood is also small： 4） E. delegatensis has the highest tangential shrinkage rate and radial-tangential shrinkage rate, andE. obliqua has the lowest. It is the variability of wood anatomical properties of these species that cause the difference in the veneer shrinkagei and then affects plywood veneer quality.展开更多
The longitudinal displacement between two reference points upon stress release was measured throgh using the CIRAD-foret one-hole method on a total of 305 trees of 6 eucalyptuses, including Eucalyptus urophylla, E. pe...The longitudinal displacement between two reference points upon stress release was measured throgh using the CIRAD-foret one-hole method on a total of 305 trees of 6 eucalyptuses, including Eucalyptus urophylla, E. pellita, E. teriticornis, E. camaldulensis, E. urophylla x E. grandis and E. urophylla × E. teriticornis. These trees were between 3 to 5 years old and are regarded as commercially important plantation species in China. Significant differences in the growth strain and diameter at breast height over bark （DBHOB） were observed between species, provenances and clones of the same age. The data clearly showed that, E. pellita, E. teriticornis and E. camaldulensis （provenance 15025） had higher growth rates but much lower growth strain at the tree surface, in comparison to other species / hybrids / clones. Whilst conclusive recommendations for species selection need to be substantiated with comprehensive studies that include other key wood properties, results of this study have shown trends pertaining to wood quality differences between the six species.展开更多
文摘The sound absorption coefficients of wood and wood boards for five eucalypt species (Eucalyptus urophylla, Euca-lyptus urophylla E. grandis, Eucalyptus urophylla E. tereticornis, Eucalyptus urophylla E. camaldulensis and Eucalyptus cloeziana) that were collected from plantation in Dongmen Forestry Center of Guangxi Province, China were tested with stand-ing wave method and their sound absorption properties were also compared. The results showed that the sound absorption co-efficients of the five eucalypt wood species did not change evidently below 1000 Hz, but above 1000 Hz their sound absorption coefficients increased with the increasing frequency. The difference in sound absorption coefficient among five species of eucalypt wood is not evident at the tested frequency range (200-2000 Hz), but the sound absorption property of Eucalyptus urophylla at low frequency is better than that of other four species. The sound absorption coefficient of the tangential-sawn board is higher than that of the radial-sawn board. The sound absorption property of eucalypt wood of 0.5 cm in thickness is much better than that of 1.0 cm in thickness. It is concluded that wood sound absorption properties of eucalypts are affected by their board thickness and the type of sawn timber within the testing frequency, but the variance of wood sound absorption property among the five tested species is not significant.
基金supported by the National Eleventh Five-Year Science and Technology (2006BAD01A15-4 and 2006bad24b0203)
文摘The effectiveness of pilodyn was tested in evaluating wood basic density, outer wood density, heartwood density, and modulus of elasticity （MoE） at 22 four-year-old eucalyptus clones in Guangxi, China. Results indicated that the mean value ranged from 9.44 to 15.41 mm for Pilodyn penetration, 0.3514 to 0.4913 g.cm^-3 for wood basic density, and 3.94 to 7.53 Giga Pascal （GPa） for MoE, respectively. There were significant differences （1% level） in pilodyn penetration between different treatments, different directions and among the clones. Generally strongly negative correlations were found between pilodyn penetration and wood properties, and the coefficients ranged from -0,433 to -0,755. Our results, together with other studies, suggest that the use of pilodyn for assessing wood density and MoE was confirmed as a possibility.
文摘This study was undertaken to determine the bending strength properties of off-cut Yellow Meranti wood by applying the finger jointed techniques. The finger orientations that were used in this study are vertical and horizontal finger orientation. Specimens were bonded with PVAc （polyvinyl acetate）. The bending strength properties were determined by the three point and four point bending test method. The results show that vertical finger orientation has the higher mean of modulus of rupture and the modulus of elasticity value of 24.49 MPa （28.91 MPa） and 8,814 MPa （11,668 MPa） respectively. However, the tested specimen properties did not meet the minimum strength of the solid （control） specimens.
基金This work was supported by both the project ( No. 30170754)from Chinese National Natural Science Fund and the national significant fundamental research 'Ascending Plan' program (No.95- 07) authorized by Ministry of Science and Technology, China. And was partly presented at the 54th Annual Meeting of the Japan Wood Research Society in Hokkaido, Japan and at the 7th Pacific Rim Bio-based Composites Symposium in Nanjing, P. R. China.
文摘Collapse-type shrinkage is one of highly refractory drying defects inlow-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD),microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP),unit cell wall shrinkage, total shrinkage and residual collapse, which are associated withcollapse-type shrinkage characteristics, were investigated by using simple regression method forthree species of collapse-susceptible Eucalyptus urophyll,, E. grandis and E. urophyllaxE.grandis,planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that:unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strongpositive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA;total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but notable to be predicted ideally by any examined factors alone owing to lower R^2 value (R^2≤0.5712);residual collapse was negatively correlated with BD and DWT, linearly positively correlated withMFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used assingle factor (R^2≥ 0.9412) to predicate unit cell wall shrinkage and RP is the relatively soundindicator for predicting residual collapse
文摘The research method in this paper is based on the standard of American Society for Testing andMaterials (ASTM). Planing and sanding are selected to study the machining properties of E. urophylla × E.grandis plantation wood. Moreover, the reasons for machining defects are analyzed. The results show E.urophylla × E. grandis planted in south China is a good species with a great potential for solid woodutilization.
基金Supported by the "948" Fund Project of Chinese State Forestry (2003-4-27, 2006-4-96)
文摘In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to conventional methods and the national standards. The effects of variances in cell wall thickness of wood fibre and vessel, and diameter of the cell lumen as well as the tissue ratio on the quality of plywood veneer were analysed. The results show that： 1） There is a great difference in fibre cell wall thickness and diameter of the cell lumen between early wood and late wood of Eucalyptus delegatensis. 2） E. obliqua has a high wood fibre tissue ratio and the thickest fibre cell wall, but the difference inthe fibre cell wall thickness between early wood and late wood is the smallest. 3） The wood fibre tissue ratio of E. regnans is smaller than that of E. obliqua, and its wood fibre cell wall isthe thinnest and there is only a very small difference in fibre cell wall thickness between early wood and late wood. The difference inthe diameter of wood fibre cell lumen among early wood, transition area and late wood is also small： 4） E. delegatensis has the highest tangential shrinkage rate and radial-tangential shrinkage rate, andE. obliqua has the lowest. It is the variability of wood anatomical properties of these species that cause the difference in the veneer shrinkagei and then affects plywood veneer quality.
文摘The longitudinal displacement between two reference points upon stress release was measured throgh using the CIRAD-foret one-hole method on a total of 305 trees of 6 eucalyptuses, including Eucalyptus urophylla, E. pellita, E. teriticornis, E. camaldulensis, E. urophylla x E. grandis and E. urophylla × E. teriticornis. These trees were between 3 to 5 years old and are regarded as commercially important plantation species in China. Significant differences in the growth strain and diameter at breast height over bark （DBHOB） were observed between species, provenances and clones of the same age. The data clearly showed that, E. pellita, E. teriticornis and E. camaldulensis （provenance 15025） had higher growth rates but much lower growth strain at the tree surface, in comparison to other species / hybrids / clones. Whilst conclusive recommendations for species selection need to be substantiated with comprehensive studies that include other key wood properties, results of this study have shown trends pertaining to wood quality differences between the six species.
