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1.
为了探索较佳的木束条尺寸,以提高杉木积成材的质量,研究了不同尺寸的杉木木束条对杉木积成材性能的影响规律,结果表明:木束条的长度对杉木积成材的纵向静曲强度、弹性模量、24h吸水厚度膨胀率有较大的影响;木束条的厚度对杉木积成材纵向静曲强度、弹性模量的影响不大,但对24h吸水厚度膨胀率、内结合强度有较大的影响;木束条的宽度对杉木积成材的物理力学性能影响极小,不存在统计意义上的影响;木束条的较佳尺寸为:长度120 mm,宽度4mm,厚度2.5 mm. 相似文献
2.
金属网/木质材料复合性能的研究 总被引:1,自引:0,他引:1
用10日不锈钢金属网与木材(速生杉木板为芯层,杨木单板为表层)进行复合试验,并与相同工艺条件下制作不加金属网的细木工板的物理力学性能进行对比分析,结果表明:在一定的工艺条件下,可以生产出具有优良性能的金属网强化细木工板。 相似文献
3.
人工林杉木和杨树木材物理力学性质的株内变异研究 总被引:4,自引:0,他引:4
按照中国国家标准研究杉木和I-214杨树木材的抗弯弹性模量、抗弯强度、顺纹抗压强度和密度,同时按照日本国家标准研究2个树种的顺纹抗剪强度.结果表明:杉木的抗弯强度、顺纹抗压强度和密度由胸高直径处向上呈波浪形增加,抗弯弹性模量则稳定降低,但不同高度间杉木的物理力学性质没有显著差异;近树皮处木材的物理力学性质高于近髓心处木材,并有极显著差异.对于I-214杨树,只有抗弯弹性模量从髓心到树皮逐渐增加,其他的物理力学性质,最小值在从髓心到树皮的过渡区,最大值在近树皮处,从髓心到树皮,杨树的物理力学性质有极显著的差异.杉木和杨树的径面顺纹抗剪强度从髓心到树皮有极显著差异,并且近树皮的高于近髓心的木材,而弦面顺纹抗剪强度从髓心到树皮没有显著差异.木材密度与力学性质有很好的线性相关关系,木材密度是一个很好的力学强度的预测手段. 相似文献
4.
以脲醛树脂作为浸渍剂,纳米SiO_2作为改性材料对速生桉木进行改性处理,以纳米SiO_2质量与脲醛树脂浸渍溶液固含量的质量比(W)、高温处理温度(H)和时间(T)作为影响因素,探究浸渍高温热处理改性对速生桉木力学性能的影响。研究结果表明:浸渍高温热处理能够提高桉木的握钉力、抗弯强度和抗弯弹性模量。当W为2%、H为180℃、T为4 h时,浸渍热处理桉木的径面和弦面握钉力达到了理想值;当W为1%、H为160℃、T为4 h时,浸渍热处理桉木的端面握钉力较为理想;当W为1%,H为160℃、T为2 h时,浸渍热处理桉木具有较好的抗弯强度和抗弯弹性模量。 相似文献
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近红外光谱分析技术在木材机械性能检测中的研究进展 总被引:1,自引:0,他引:1
近红外光谱技术具有快速、无污染、成本低廉、准确性高等优点,相比其他无损检测方法,被广泛应用于农业、医学、化工、造纸等各个领域。国内外许多科研工作者在木材材性分析和检测方面也作了大量的探索。本文主要介绍木材材性分析的重要性、近红外光谱技术的基本原理和特点,国内外林业科技工作者在辐射松、蓝桉、火炬松和粗皮桉等不同树种木材的抗弯强度、抗弯弹性模量、密度和压缩强度等物理力学性质检测方面所做出的贡献和取得的进展,通过介绍可以看出NIR技术具有很大的潜能,它可以快速、准确的获悉木材的性质,从而对木材进行科学合理的利用。 相似文献
7.
Laszlo Horvath Ilona Peszlen Perry Peralta Steve Kelley 《Wood Science and Technology》2011,45(2):303-314
The investigation of genetically modified trees requires rapid and reliable techniques to measure the mechanical properties
at an early age in order to give timely feedback to forest geneticists. In this study, transmittance near-infrared (NIR) spectroscopy
was used to predict the green mechanical properties of 1- and 2-year-old transgenic and wild-type aspen. Green modulus of
elasticity (MOE) in three-point bending and green ultimate compression strength (UCS) parallel to the grain were predicted
from the NIR spectra of dry wood meal pellets. Green UCS had strong correlation (R
2 = 0.91) and green MOE had good correlation (R
2 = 0.78) with the spectra. The latter could be explained by the moderate correlation of MOE with the lignin content of the
transgenic samples, suggesting that besides chemical composition MOE also depends on anatomical properties. The ratio of performance
to deviation value suggested that the calibration model of both UCS (2.94) and MOE (1.91) could be used for screening. 相似文献
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9.
利用杨树人工林剩余物生产刨花板可行性研究 总被引:1,自引:0,他引:1
The composite board industry in Iran is obliged to use residues from forest operation as well as wood industry for competing
with paper industry because of shortage of wood. In the present study we investigated the residues from poplar plantation
used for particleboard production. Three kinds of wood materials, poplar branches, small diameter poplar wood (3–8 cm) and
beech wood, were used in the experiment of particleboard production. The results demonstrated that the characteristic of particleboard
made from poplar branches and small diameter wood is comparable to that made from mature beech wood. To avoid too much residual
acid in the final board, the properties of boards produced with 1.5% hardener at 175°C press temperature are acceptable, although
the properties of particleboard produced with 2% hardener were higher than were higher than that of the board produced with
lower hardener (1% or 1.5%).. The MOR, MOE and IB of particleboard made from branches were measured as 14.57, 2015, and 1.32
MPa, respectively, while The MOR, MOE and IB of particleboard produced from small diameter poplar wood were 19.90, 2199, and
1.86 MPa, respectively. The thickness swelling of boards made from branches after 2 and 24 h immersion in water was 20.14%
and 31.26%. The utilization of branches and very small diameter wood of poplar is recommended for the survival and developments
of particleboard industry in Iran. 相似文献
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11.
Miloš Ivković Washington J. Gapare Aljoy Abarquez Jugo Ilic Michael B. Powell Harry X. Wu 《Wood Science and Technology》2009,43(3-4):237-257
Development of optimal ways to predict juvenile wood stiffness, strength, and stability using wood properties that can be measured with relative ease and low cost is a priority for tree breeding and silviculture. Wood static modulus of elasticity (MOE), modulus of rupture (MOR), radial, tangential, and longitudinal shrinkage (RS, TS, LS), wood density (DEN), sound wave velocity (SWV), spiral grain (SLG), and microfibril angle (MFA) were measured on juvenile wood samples from lower stem sections in two radiata pine test plantations. Variation between inner (rings 1–2 from pith) and outer (rings 3–6 from pith) rings was generally larger than that among trees. MOE and MOR were lower (50%) in inner-rings than in outer-rings. RS and TS were higher (30–50%) for outer-rings than inner-rings, but LS decreased rapidly (>200%) from inner-rings to outer-rings. DEN had a higher correlation with MOR than with MOE, while MFA had a higher correlation with dry wood MOE than with MOR. SLG had higher significant correlation with MOE than with MOR. DEN and MOE had a weak, significant linear relationship with RS and TS, while MOE had a strong negative non-linear relationship with LS. Multiple regressions had a good potential as a method for predicting billet stiffness (R 2 > 0.42), but had only a weak potential to predict wood strength and shrinkage (R 2 < 0.22). For wood stiffness acoustic velocity measurements seemed to be the most practical, and for wood strength and stability acoustic velocity plus core density seemed to be the most practical measurements for predicting lower stem average in young trees. 相似文献
12.
Boštjan Lesar Miha Humar Frederick A. Kamke Andreja Kutnar 《Wood Science and Technology》2013,47(5):977-992
Hybrid poplar (Populus deltoides × Populus trichocarpa) and Douglas-fir (Pseudotsuga menziesii) wood specimens were densified with three variations of thermo-hydro-mechanical (THM) treatment. The THM treatments differed in the steam environment, including transient steam (TS), saturated steam (SS), and saturated steam with 1-min post–heat treatment at 200 °C (SS+PHT). The bending properties, FTIR spectra, and colour of the THM wood specimens were studied before and after exposure to two different wood decay fungi, brown rot Gloeophyllum trabeum, and white rot Trametes versicolor. The results showed that the performance of densified hybrid poplar wood was considerably poorer than the performance of Douglas-fir heartwood. The FTIR spectra measurements did not show changes in the densified hybrid poplar wood, while some changes were evident in densified Douglas-fir specimens. After fungal degradation, the most prominent changes were observed on the SS+PHT specimens. Colour is one of the most important parameter predominantly influenced by the wood species and the intensity of the densification process for both wood species, while after fungal exposure, the colour of all densified Douglas-fir specimens obtained more or less the same appearance, and densified hybrid poplar specimens resulted in lighter colour tones, indicating that the pattern of degradation of the densified and non-densified specimens are similar. The 3-point bending test results determined that the THM treatment significantly increased the modulus of rupture (MOR) and modulus of elasticity (MOE) of the densified wood specimens, while fungal exposure decreased the MOE and MOR in hybrid poplar and Douglas-fir specimens. 相似文献
13.
Connection plays an important role in structural components and end jointing is one of the most common connections in structural applications.This study was designed to investigate some mechanical properties (MOE and MOR) of solid wood samples manufactured from poplar (Populus nigra),joined together through end jointing.As well,we studied combinations of lumber manufactured from 10-mm veneer,using a polyvinyl acetate adhesive.The results show that non-jointed lumber (control samples) have better bending properties (MOE and MOR) than jointed specimens and lumber made from laminated layers.On the whole,side-byside joints have a negative effect on the MOR and MOE of laminated products,which is more pronounced in the MOR.By increasing the number of joints,the properties of combination of three-ply,i.e.,bending strength and modulus of elasticity,decreased. 相似文献
14.
In this report, the 575 specimens were divided into ten groups based on range of growth ring width. The modulus of elasticity
(MOE) and modulus of rupture (MOR) of 45 × 90 mm specimens of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation dimension lumber were analyzed by average growth ring width and average density of each group.
The results showed that the average growth ring width was in inverse proportion to density, MOE, and MOR of the dimension
lumber. Furthermore, average density was in direct proportion to MOE and MOR of the dimension lumber. The coefficient of determination
(R
2) for all the regression equations ranged from 0.7340 to 0.9207 at a significance level of 0.001. However, without such group
classification, there was poor relationship between growth ring width, density, MOE, and MOR with a determination coefficient
of 0.0901–0.1855. This finding suggested that it was feasible to predict the flexural properties of Chinese fir plantation
dimension lumber by average growth ring width after specimen group classification. 相似文献
15.
对杉木素材与聚乙烯醇缩甲醛浸渍处理材的物理与力学性能进行了对比研究,并利用扫描电子显微镜(SEM)分析了改性剂在木材中的分布情况。结果表明:随着改性剂浓度的提高,改性材的气干密度和抗缩系数均逐渐提高,气干密度最大可达0.4 g/cm3,提高了5.7%,抗缩系数最大提高了18.8%;改性材的吸水率逐渐下降,最多下降了21.1%;当改性剂浓度为30%时,改性材的破坏极限和弹性模量分别提高了6.7%和35.3%;当改性剂浓度为15%时,静曲强度下降了9.9%。SEM结果表明,改性剂填充于部分木射线以及交错纤维间的空隙中。 相似文献
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17.
压前含水率对杉木间伐材压缩木性能的影响 总被引:3,自引:0,他引:3
通过对杉木间伐材压缩密化的水分和物理力学性能进行分析,并观察木材微观结构的变化,可得出以下结果:1)压缩木各方向的水分分布不均匀,容易翘曲变形;2)水分对压缩木的物理力学性能有影响,压前含水率50%左右,压缩木硬度、抗弯弹性模量和抗弯强度最大,但冲击韧性随着压前含水率的增加呈下降趋势。从微观结构的观察可知,杉木间伐材压缩木的细胞只是被挤压,细胞腔变小而细胞壁未受到破坏。为了降低压后含水率,使水分分布均匀,可以采取两种办法:一是使初始含水率尽可能低,二是热压时间尽可能长。 相似文献
18.
Evaluation of thermally modified beech and spruce wood and their properties by FT-NIR spectroscopy 总被引:2,自引:2,他引:0
Helmut Bächle Bernhard Zimmer Elisabeth Windeisen Gerd Wegener 《Wood Science and Technology》2010,44(3):421-433
Quality assessment of thermally modified spruce (Picea abies (L.) Karst) and beech (Fagus sylvatica L.) wood and of the corresponding reference samples was carried out by means of non-destructive FT-NIR spectroscopic measurements
and PLS regression. Oven-dry and basic density as well as MOE and MOR determined by 3-point bending tests were evaluated.
The focus was put on specimens produced from material that had been thermally modified in an industrial scale kiln. Modelling
results range from poor to very good. The results of the spectra taken from the spruce samples resulted in better prediction
results than the spectra of the beech samples. This could be due to different proveniences or variation in the industrial
modification process. The results indicate that FT-NIR surface measurements of sound thermally modified wood samples could
be applied to evaluate several characteristics before and after the modification process. The method could be used for screening
during pre-sorting of thermally modified wood. 相似文献
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20.
XU Ming REN Haiqing LI Xiazhen 《中国林业科技(英文版)》2007,6(3):40-44
The variation of tensile strength parallel to grain in Chinese fir and 1-214 poplar wood from plantations was studied in this paper. Aaccording to the national standards The Testing Methods for Physical and Mechanical Properties of Wood (GB 1927 to 1943 -- 1991), the small clear wood samples were cut and tested, which represent the south and north of trees with heights of 1.3, 3.3, 5.3 and 7.3 m. The results showed: the tensile strength parallel to grain of the north wood was higher than that of south wood. ANOVA shows that the tensile strength parallel to the grain with height is of significant difference (at 0.05 level). 相似文献