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1.
Tomoyuki Hayashi Atsushi Miyatake Feng Fu Hideo Kato Masahiko Karube Masaki Harada 《Journal of Wood Science》2005,51(5):486-491
To investigate the durability of structural laminated veneer lumber (LVL), outdoor exposure tests have been conducted since
1990 at a field-testing site at the Forestry and Forest Products Research Institute. This article is the second interim report
on the results after 9 years of exposure. Seven kinds of structural LVL with no preservative treatment were subjected to the
tests. Almost all the exposed specimens were decayed by a kind of brown rot fungi (Pseudomerulius aureus (Fr.) Julich). The degree of decay varied with wood species; grand fir and western hemlock LVL in particular showed weak
resistance against the decay. All the specimens were stored for more than 1 year in a testing room conditioned at 20°C and
65% relative humidity. We then measured the ultrasonic velocity of the specimens by the Pundit method, penetration depth by
the Pilodyn method, and bending strength by a conventional bending test. Correlation between nondestructive measurement factors
and the density was strong even on LVL with many adhesive layers. The nondestructive testing method was found to be applicable
to LVL as well as solid lumber. After the nondestructive measurements, each LVL was cut into three types of specimen (top:
T, middle: M, and bottom: B) for the bending tests. The bending strength varied with the type of specimens. Correlation between
modulus of elasticity and modulus of rupture was strong even in the decayed specimens. 相似文献
2.
An outdoor exposure test was conducted on kenaf core binderless boards (pressing temperatures 200°, 180°, and 160°C; pressing
pressure 3.0 MPa, time 10 min, target board thickness 5 mm, target board density 0.8 g/cm3) to estimate their bond durability. Modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding strength (IB),
thickness change, weight loss, Fourier transform infrared (FTIR) spectra, and color difference (ΔE*) by the CIE L*a*b* system were measured at various outdoor exposure periods up to 19 months. These values were then compared with those of a
commercial medium-density fiberboard (MDF; melamine-urea-formaldehyde resin; thickness 9.0 mm, density 0.75 g/cm3). Generally, dimensional stability and the retention ratios of MOR, MOE, and IB after the outdoor exposure test increased
with increased pressing temperature of binderless boards. The MOR retention ratio of the kenaf core binderless boards with
a pressing temperature of 200°C was 59.5% after 12 months of outdoor exposure, which was slightly lower than that of the MDF
(75.6% after 11 months of outdoor exposure). Despite this, the bond durability of the kenaf core binderless boards should
be viewed as favorable, especially when considering the fact that the retention ratio of 59.5% was achieved without binder
and without obvious element loss.
Part of this report was presented at the International Symposium on Wood Science and Technology, IAWPS2005, November 27-30,
2005, Yokohama, Japan 相似文献
3.
The embedment tests of laminated veneer lumber (LVL) with two moduli of elasticity (MOE; 7.8 GPa and 9.8GPa), parallel strand lumber (PSL), and laminated strand lumber (LSL) were conducted in accordance with ASTM-D 5764. The load-embedment relation for each of these engineered wood products (EWPs) was established. The directional characteristics of bearing strength (e), initial stiffness (k
e), and effective elastic foundation depth were obtained from the tested results. The effective elastic foundation depth (=E/k
e,E = MOE), based on the theory of a beam on elastic foundation, was obtained from thek
e and MOE. An of 90° (perpendicular to the grain) was calculated by dividingE
90 [MOE of 90° from the compression test, but MOE of 0° (E
0), parallel to the grain, obtained from the bending test] byk
e90, the initial stiffness of 90°. This study aimed to obtain the bearing characteristics of each EWP, taking into consideration their anisotropic structures, for estimating the fastening strength of a dowel-type fastener. The relations between the bearing coefficients (
e,k
e,) on the loading direction and dowel diameter were established from the load-embedment curves. Based on the results of the embedment test, tested EWPs showed different tendencies in all directions from wood and glued laminated timber.Part of this study was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999 相似文献
4.
Tekat Dwi Cahyono Wayan Darmawan Eka Novriyanti 《Wood material science & engineering》2020,15(3):155-162
ABSTRACTA study to determine the quality of laminated veneer lumber (LVL) from samama wood (Anthocephalus macrophyllus) was carried out. Samama is a fast-growing endemic wood in eastern Indonesia. Factorial of three factors in RAL design was used to investigate the influence of veneer thickness, juvenile proportion and veneer lay-up to the quality of the resulted samama LVL. The veneer thicknesses were 1.5 and 3.0?mm. Juvenile proportions were arranged in five levels, which were 100% of juvenile veneer, 100% of mature veneer and combination of both juvenile and mature with juvenile proportion of 14%, 43% and 71%. Two veneer lay-up used in this study were loose side met loose side and tight side met loose side. The result of the study showed various specific gravity of LVL by different proportions of juvenile. This factor also affected the other physical traits. Shear strength of the LVL was equal to the solid wood, yet MOE and MOR were affected by juvenile proportion and veneer lay-up. LVL developed from 100% of mature veneer exhibited the highest MOE and MOR, yet no significant difference was noted in MOE and MOR between LVL 100% of juvenile and other tested juvenile proportions. 相似文献
5.
To find a desirable method for estimating the length effect on tensile strength (
t), we used three methods to analyze the
t data from a Japanese larch (Larix kaempferi) small, clear specimen. These methods included a nonparametric method, the projection method of Hayashi, and a proposed method. The estimated length effect parameters (g) by the nonparametric method were 0.0237 and 0.0626 for 50th and 5th percentile
t distributions, respectively. The projection method requires a standardE
f level (E
*: dynamic Young's modulus), arbitrarily chosen for calculating theg value. Theg values from the projection method were 0.1122 for lowE
*, 0.0898 for averageE
*, and 0.0759 for highE
*. The estimatedg values by the proposed method using selected
t data were 0.1020 and 0.1838 for the 50th and 5th percentiles, respectively. Among the three methods, the nonparametric method did not consider the different distribution of Young's modulus among specimens, and the estimated length effect parameters (g) by this method were small. The projection method reduced the influence of Young's modulus, but the length effect parameters varied with theE
* level. The proposed method minimized the dependence onE
f distributions among specimens. we believe the latter method is desirable for estimating the length effect on tensile strength. 相似文献
6.
The effect of plantation spacings (types A-E) on the bending strength and dynamic modulus of elasticity of 41-year-old Taiwan-grown cedar (Cryptomeria japonica D. Don) was investigated. The results indicate that the highest values for the static bending modulus of elasticity (MOE), modulus of rupture (MOR), and dynamic modulus of elasticity (ED, E
Dt) occurred in trees obtained from those most densely planted (type A); there was a significant difference between type A and the other four spacing types (B, C, D, and E), but there were no significant differences among those four types. Interrelations among MOE, MOR, E
D, and E
Dt could be represented by positive linear regression formulas, which revealed highly significant differences. The relations among the square value of stress-wave transmission velocity (Vt
2 and Vt
2) and MOE, MOR, E
Dl, and E
Dt, respectively, could be represented by positive linear regression formulas. The differences were highly significant.Part of this report was presented at the International Wood Engineering Conference '96, New Orleans, LA, USA, October 1996 相似文献
7.
Kiyohiko Fujimoto Yasushi Hiramatsu Atsushi Miyatake Kenta Shindo Masahiko Karube Masaki Harada Seiichiro Ukyo 《Journal of Wood Science》2010,56(6):444-451
The object of this study was to investigate the strength properties of edge-glued laminae and to propose a suitable grading
method based on the lamina modulus of elasticity (MOE). Edge-glued laminae composed of lumber with similar MOEs (uniform laminae)
and edge-glued laminae produced by randomly gluing lumber independent of MOE (random laminae) were made from karamatsu (Larix kaempferi) lumber having the same thickness and length, but various widths. For both the uniform and random laminae, there was a strong
correlation between MOE values measured using the longitudinal vibration technique, the static bending test, and a grading
machine. The average values of bending, tensile, and compressive strengths of the uniform laminae were similar to those of
the random laminae. On the other hand, the average strength of laminae without end joints was significantly higher than that
of finger-jointed laminae for both uniform and random laminae. Finger-joints and knots played a significant role in the failure
of specimens, but the edge-gluing and the difference in MOE within an edge-glued lamina did not appear to affect the strength
properties. The bending, tensile, and compressive strengths of edge-glued laminae were strongly correlated to the lamina MOE. 相似文献
8.
Until now we developed an estimation method for strength distributions of laminated veneer lumber (LVL) element by nonlinear least-squares method (NLM). Estimated strengths by this method were modulus of elasticity (MOE) and modulus of rupture (MOR) in the horizontal use direction and the vertical use direction, tensile strength and compression strength. But to use LVL for structural members, shear strength was also needed. Therefore, we tried to estimate the shear strength distribution of LVL element by NLM same as MOE and MOR in the horizontal use direction and the vertical use direction, the tensile strength of LVL and the compression strength of LVL in the previous reports. We conducted shear strength test for LVL and estimated element shear strength distribution by LVL strength data in the horizontal and vertical use direction. Next, we simulated LVL shear strength distribution using element shear strength distribution and compared with experimental ones in each use direction. They were overlapped in both use direction. Therefore, we could validate NLM for estimating element shear strength distribution. 相似文献
9.
10.
《Wood material science & engineering》2013,8(4):186-195
Abstract This work was an investigation of the effect of nanoparticles on the durability of wood specimens exposed to artificial weathering. TiO2 and clay nanoparticles were mixed with preservative (Wolmanit CX-8) for improving the durability of Norway spruce (Picea abies). Impregnated and untreated specimens were subjected to Atlas Solar Simulator accelerated ageing test chamber for solar radiation and water spray exposure. The effectiveness of the treatment against colour and chemical changes was investigated using CIEL*a*b* colour measurements system and Fourier transform infrared analysis. The present study showed that the wood specimens that had been treated with preservatives containing nanoparticles were slightly more stable against artificial ageing than both untreated specimens and specimens treated with preservative alone. 相似文献
11.
介绍了单板层积材、密实型单板层积材在国内外的研究和利用概况.探讨了采用低分子量酚醛树脂浸渍处理杨木单板的方法制备杨木单板层积材的生产技术.结果表明:施胶量相当时,浸渍方式与涂胶方式生产的单板层积材相比,密度相当,吸水厚度膨胀(24hTS)降低了24%,胶合强度提高了:16%,弹性模量(MOE)和静曲强度(MOR)分别提高了20.17%和44.76%.采用浸渍树脂方式生产的密实型强化杨木单板层积材随着吸药量的增多,密度增大;24hTS减小;胶合强度随着吸药量的增加先增大而后趋于平稳;MOE和MOR先增大后减小.当吸药量为168%时,MOE、MOR达到最大,分别为15.34GPa和135.31 MPa.密实型强化单板层积材能够满足建筑和木结构等结构材要求,具有良好的发展空间. 相似文献
12.
To control reliably the suitable use of curved laminated veneer lumber (LVL) as a structural member of furniture, stress distributions and failure types of curved LVL made from massion pine (Pinus massoniana Lamb.) and fast-growing poplar (Populus euramericana CV. I.) were investigated under end-pull, end-thrust, and transverse loading. The results are summarized as follows: In curved LVL of two wood species, absolute values of the maximum axial stress (
A) occurring at the convex surface are smaller than those (
B) that occurred at the concave surface. The differences between these values decrease with an increase in the radius of curvature. With end-pull loading, there were mainly splitting failures at glue lines near the centroidal axis. With end-thrust loading, there were more fibrous fractures on the tensile side and crushing failures on the compression side. With transverse loading, curved specimens of massion pine exhibited mainly splitting failures. In contrast, for curved LVL of fast-growing poplar, fibrous fractures occurred mainly on the tensile side. Absolute values of
A and
B significantly increased with an increase in the radius of curvature. In contrast, absolute values of the maximum radial stress (
R,) decreased with an increase in the radius of curvature. Absolute values of
A,
B, and
R of curved LVL of massion pine were larger under end-thrust loading than under end-pull and transverse loading. Conversely, absolute values of
A and
B of curved LVL of fast-growing poplar were small under end-thrust loading. However, absolute values of
A and
B of curved LVL of two wood species under end-pull loading were almost similar to those under transverse loading.Part of this study was presented at the 10th annual meeting of Chugoku Shikoku branch of the Japan Wood Research Society, Miki, Kagawa, September 25, 1998 and the 4th Pacific Rim Bio-Based Composites Symposium, Bogor, Indonesia, November 2–5, 1998 相似文献
13.
Key message
Pilodyn and acoustic velocity measurements on standing trees, used for predicting density and stiffness, can be good genetic selection tools for black spruce. Genetic parameters and selection efficiency were conserved in two breeding zones with contrasted bioclimatic conditions.Context
Given the recent progress made in the black spruce genetic improvement program, the integration of juvenile wood mechanical properties as selection criteria is increasingly relevant.Aims
This study aims to estimate the genetic parameters of in situ wood density and modulus of elasticity (MoE) measurements and to verify the efficiency of various measuring methods used for large-scale selection of black spruce based on wood quality.Methods
Height, diameter, wood density, and some indirect measures of density (penetration and drilling resistance) and MoE (acoustical velocity and Pilodyn) were estimated on 2400 24-year-old trees of 120 open-pollinated families in progeny trials located in the continuous boreal or mixed forest subzones.Results
Heritability of growth, density, and indirect density measurements varied from low to moderate and was moderate for acoustical velocity in both vegetation subzones. Expected genetic gains for wood properties based on in situ methods were higher for MoE proxy estimation combining Pilodyn and acoustic velocity.Conclusion
Acoustic velocity is a good predictor of MoE. It is virtually unaffected by the environment and can be used on a large scale in the same manner as the Pilodyn for density. Using a proxy estimation that combines both methods helps optimize genetic gain for MoE.14.
The objectives of this study were to establish the method of evaluating wood mechanical properties by acoustic nondestructive
testing at standing trees and at logs of a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation, and to compare three acoustic nondestructive methods for evaluating the static bending modulus
of elasticity (MOE), modulus of rupture (MOR), and compressive strength parallel-to-grain (σc) of plantation wood as well. Fifteen Chinese fir plantation trees at 36 years of age were selected. Each tree was cut into
four logs, for which three values of dynamic modulus of elasticity, i.e., E
sw, of the north and south face based on stress waves to assume the measuring state of the standing tree, E
fr, longitudinal vibration, and E
us, ultrasonic wave, were measured in the green condition. After log measurements, small specimens were cut and air-dried to
12% moisture content (MC). Static bending tests were then performed to determine the bending MOE and MOR, and compressive
tests parallel-to-grain were made to determine σc. The bending MOE of small clear specimens was about 7.1% and 15.4% less than E
sw and E
us, respectively, and 11.3% greater than E
fr. The differences between the bending MOE and dynamic MOE of logs as determined by the three acoustic methods were statistically
significant (P < 0.001). Good correlation (R = 0.77, 0.57, and 0.45) between E
sw, E
fr, and E
us and static MOE, respectively, were obtained (P < 0.001). It can be concluded that longitudinal vibration may be the most precise and reliable technique to evaluate the
mechanical properties of logs among these three acoustic nondestructive methods. Moreover, the results indicate that stress
wave technology would be effective to evaluate wood mechanical properties both from logs and from the standing tree. 相似文献
15.
Eitaro Fukatsu Akira Tamura Makoto Takahashi Yoko Fukuda Ryogo Nakada Masahiro Kubota Susumu Kurinobu 《Journal of Forest Research》2011,16(2):128-135
The efficiency of the indirect selection for wood density using the Pilodyn in Cryptomeria japonica was studied by comparing the Pilodyn penetration (PP) depth and the direct measurement of wood density in three test sites.
The influence of the genotype by environment (G × E) interaction of wood density was estimated using the Pilodyn with common
12 C. japonica clones in 10 test sites in Kanto breeding region in Japan. The PP depth was highly correlated with wood density, and the
genetic correlation between them was −0.88. The indirect selection using the Pilodyn realized 87% of the genetic gain obtained
by the direct selection of wood density. The G × E interaction in PP depth was small. The ratio of the variance component
of the G × E interaction to that of genotype was only 0.096 in the PP depth, whereas it was 0.700 in tree height and 1.410
in diameter at breast height. These findings indicate that the Pilodyn is useful for the genetic improvement of wood density
in Cryptomeria japonica. The small G × E interaction in wood density estimated using the Pilodyn indicates that the relative clonal performance in
wood density is stable among diverse environments in Kanto breeding region in Japan. 相似文献
16.
Sugi (Cryptomeria japonica D. Don) is one of the most important planted trees in Taiwan. The normal heartwood of sugi has a red to pinkish rose color. Unfortunately, this pleasant appearance is susceptible to discoloration after environmental exposures. This discoloration is a serious defect that decreases the value of sugi products. The objective of this study was to investigate the effects of environmental factors such as moisture, oxygen, and lights of different wavelengths on the discoloration of sugi. The results show that under the combined effects of light and oxygen the color of heartwood changes from red (or rosepink) to bluish green. The color further darkens and eventually turns to black with the presence of moisture. As for the effect of light wavelengths on the discoloration of sugi heartwood, it was found that the red color was enhanced after being irradiated with light of wavelengths above 600 nm. Botha
* andb
* values increased significantly as a result of such exposure. 相似文献
17.
Accurate prediction of whole-tree wood basic density (BD) from indirect density measures is important for estimating Eucalytpus globulus breeding values and genetic gain. We measured 100 E. globulus trees at 6.5 years of age on each of a high productivity site (Albany) and a low productivity site (Esperance), sampling
16 full-sib families and seven open-pollinated ‘check’ seedlots. On each tree we assessed pilodyn penetration at 1.3 m and
BD of: (a) the outer 10 mm which was penetrated by the pilodyn pin of a bark-bark core, (b) a whole bark-bark core at 1.3 m,
(c) a cross-sectional disk at 1.3 m and (d) the whole tree, represented by cross-sectional disks at five heights. Site effects
and genetic values for families and checks were determined by mixed model analysis. A trend of increasing BD from pith to
bark was more pronounced at Albany, where wood formed before age 3.5 years was 12 kg/m3 less dense than at Esperance (P = 0.01) and wood formed from 3.5 to 6.5 years was 27 kg/m3 denser than at Esperance (P < 0.001). Mean whole-tree BD was 19 kg/m3 greater at Albany (P < 0.001). Pilodyn penetration was well-correlated with BD of the 10 mm sample of penetrated wood and this relationship was
not greatly affected by site variation. Genetic values for pilodyn penetration formed precise relationships with BD of breast-height
discs and whole-tree BD although they were site-specific. Pilodyn penetration was a better predictor for genetic values of
whole-tree BD than were bark-bark cores. 相似文献
18.
Matthew D. Aro Xiping Wang Dwight E. McDonald Marshall Begel 《Wood material science & engineering》2017,12(4):228-235
Laminated strand lumber (LSL) and laminated veneer lumber (LVL) were thermally modified as a post-treatment at 140°C, 150°C, 160°C, 170°C, and 180°C. The tension modulus of elasticity (MOE) of LSL was not significantly impacted by the treatments, with the 180°C treatment group exhibiting the highest tension MOE (11.8?GPa). The LVL also experienced minimal impacts, with the 150°C treatment group having the highest tension MOE (19.4?GPa) and the 160°C treatment group exhibiting the lowest (17.1?GPa). The maximum tensile strength (MTS) of the LSL and LVL significantly decreased with increasing temperatures, with the control and 180°C treatment groups experiencing the highest and lowest MTS, respectively. The lowest MTS for LSL was 10.8?MPa (180°C treatment), which was 70% lower than the controls. The lowest MTS of the LVL was 24.4?MPa (also at the 180°C treatment), which was a 49% decrease compared to the controls. These results suggest that thermal-modification post-treatments minimally impact tension MOE, but can significantly reduce MTS at higher treatment temperatures. Combined with previous work improving the moisture properties and equilibrium moisture content of thermally modified LSL and LVL, it may be possible to optimize the treatment technique(s) to yield products with desirable properties. 相似文献
19.
Colorimetry of wood specimens from French Guiana 总被引：1，自引：0，他引：1
Yoshihiko Nishino Gérard Janin Bernard Chanson Pierre Détienne Joseph Gril Bernard Thibaut 《Journal of Wood Science》1998,44(1):3-8
The color of 97 species of wood specimens from French Guiana was measured on their radial and tangential surfaces with a colorimeter. We obtained the tristimulus values of X, Y, and Z of the 10° standard observer under the illuminant of D
65, and the values of the CIELAB color system, L
*, a*, b*, C*, and h. When the lightness index (L
*) was <54, b
*, C
*, and h showed positive correlations against L
*. When L
* was >54, a
* and C
* showed negative correlations against L
*. These results imply that wood color should be discussed by separating wood specimens into the high and low-lightness groups. A good positive correlation was found between the L
* and h throughout the whole range of L
*. It is thought that the value of h can be an important index, as can L
*, for comparing of wood color because h shows a simple relation with L
*. 相似文献
20.
ABSTRACTCertain important quality parameters of red maple (Acer rubrum) laminated veneer lumber (LVL) impregnated with three waterborne formulations: copper azole (CA-B), micronized copper azole (MicroCA or MCA) and alkaline copper quaternary (ACQ-D) bonded with phenol formaldehyde or cross-linked polyvinyl acetate (XPVAc) adhesives were evaluated. Pre-dipping of veneers before LVL production and two post-manufacturing procedures, viz., vacuum-pressure and post-dipping of LVL, were applied. Maximum copper retention in pre-dip-treated, vacuum-pressure and post-dip-treated LVL was 1.4, 9.7 and 1.7?kg/m3, respectively. Copper retention in MCA-treated LVL was relatively lower than soluble formulations. Various physical, mechanical and bonding properties of treated LVL such as density, water absorption, swelling, flexural properties, hardness, tensile shear strength, delamination and wood failure (%) were studied and compared with untreated LVL. Little to negligible deleterious effect was observed on properties of LVL due to these chemical treatments. Analysis of variance results showed that most of properties of red maple LVL were not significantly different compared with those of untreated LVL. Therefore, vacuum-pressure impregnation process can be used to treat the red maple LVL with novel micronized copper formulations for increasing the service life of such products against biodegradation without affecting techno-mechanical quality parameters. 相似文献