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Research on the mechanical and physical properties of wood is commonly carried out on either small clear specimens or structural-sized boards. The first approach was more frequently utilized in the past, while the latter is more commonly used nowadays. However, there is very little information on how the two approaches relate with one another. This study aimed to quantify the relationships between the mechanical [modulus of elasticity (MOE) and bending strength] and physical properties (density) of both specimen sizes. A total of 1376 structural-sized boards from three different species (Douglas-fir, Norway spruce and Sitka spruce) were tested in bending, after which a small clear specimen was extracted from the undamaged portion of each board and re-tested in bending. Prior to destructive testing, all boards and clear specimens were evaluated using non-destructive technology. Poor-to-moderate relationships were found between all measured mechanical and physical properties of structural-sized timber and small clear specimens. In both specimen sizes, the properties correlated with one another within the same specimen size, as well as across the two sizes. The strength of correlations appears to be somewhat species dependent. Relatively good relationships were identified when comparing the mean tree values of the properties examined, suggesting either method can be used for a tree-level comparison. The non-destructive evaluation of specimens was shown to reflect the measured properties moderately well, with the relationships changing significantly depending on which measured property was being predicted. [ABSTRACT FROM AUTHOR]

In Ireland, most structural timber from Sitka spruce (Picea sitchensis [Bong.] Carr.) is machine graded into C16 strength class. However, timber from early thinnings is mostly used for non-structural applications. There is an increased demand for structural timber, and timber from young trees could contribute to wood supply. However, this timber has lower mechanical properties than mature timber. In order to pre-sort the resource for structural application of wood from thinning, the possibilities of acoustic and density (D) measurements on young trees and logs have been investigated. The stress wave velocity (SWV) and pin penetration depth (PD) were measured on standing trees, which were then felled and cut into 10-m-long logs and subsequently into 3-m-long logs. Fundamental frequency was measured on logs. Finally, the logs were processed into boards, which were tested in accordance with EN 408 to obtain modulus of elasticity (MOE) in bending, bending strength (BStr) and D. The results showed good relationships between timber properties and acoustic and D measurements. Models for predicting grade properties of timber from thinnings are presented. Pre-sorting of young Sitka spruce trees and logs helped obtain higher C16 yields. [ABSTRACT FROM AUTHOR]

The shear moduli (SM) of solid wood in the longitudinal-radial (LR) and radial-tangential (RT) planes of Sitka spruce are extremely different from each other and were obtained via a torsional vibration (TV) test by varying the aspect ratios and conducting subsequent numerical analyses. The SM in both planes were accurate, when the aspect ratios of the specimens were appropriately selected, even though the SM around the torsional axis were extremely different from each other. [ABSTRACT FROM AUTHOR]

The shear moduli (SM) of solid wood in longitudinal- radial (LR) and longitudinal-tangential (LT) planes were obtained via a torsional vibration (TV) test by varying the aspect ratios of Sitka spruce specimens and conducting subsequent numerical analyses. A pair of specimens with different aspect ratios was used to separate the SM in the LR and LT planes from each other, and the effect of the aspect ratio was examined. The experimental and numerical results indicated that the SM can be accurately obtained via TV test, when the aspect ratios of the specimens are appropriately determined. [ABSTRACT FROM AUTHOR]

The cryptic lifestyle of drywood termites makes it difficult to study their foraging behaviour and to detect infestations in hidden regions. In the present research, computer tomography (CT) scanning images were collected over a 1-year observation period of drywood termite Incisitermes minor (Hagen) in order to understand its foraging behaviour and, perhaps, to be able to detect the infestation as early as possible. Sitka spruce and Japanese cypress woods were the test objects. As CT scanning results show, foragers caused distinguished tunnelling patterns based on the physical properties of wood during gallery construction. The foragers primarily excavate along the earlywood in radial direction towards the outer surface of the wood to establish the primary and satellite chambers, followed by mainly superficial (0.3-3.0 cm under the surface) longitudinal expansion with occasional lateral deviations. The development of tunnelling is affected by the physical constraints of knots with their high density, high extractive and lignin contents, reaction wood (compression wood) and wood damage caused by wind. [ABSTRACT FROM AUTHOR]

Open-hole compression tests on Sitka spruce (Picea sitchensis Carr.) were conducted, and the effect of the hole notch on the compressive strength has been investigated. A circular hole was cut at the centre of the longitudinal (R)-radial (R) plane. A compression load was applied to the specimen along the L or R direction, and the nominal stress at the onset of nonlinearity and the nominal compressive strength were obtained. In the test, the diameter of the hole was varied, and the effect of the diameter was analysed based on point stress criterion (PSC). It was revealed that the notch sensitivity of Sitka spruce was not so significant, and this tendency was more pronounced for the compressive strength in the R direction than in the L direction. Despite the notch insensitivity, however, the open-hole compressive strength could be predicted appropriately by the PSC. [ABSTRACT FROM AUTHOR]

Tonewood for musical instruments is quarter-sawn and frequently quality-graded based on visual appearance, mechanical and acoustic properties. The assessment uses simple human (subjective) observation, and two 'experts' can rate the same sample differently. This paper describes the application of integral transforms (Fourier and Radon) for automatic (objective) assessment of the visual appearance of 10 Sitka spruce ( Picea sitchensis) sample images. This work considers surface classification on the basis of grain orientation, count, spacing, and evenness or uniformity. [ABSTRACT FROM AUTHOR]

Sitka spruce ( Picea sitchensis) is the most widely planted commercial tree species in the United Kingdom and Ireland. Because of the increasing use of this species for construction, the ability to predict wood stiffness is becoming more important. In this paper, a number of models are developed using data on cellulose abundance and orientation obtained from the SilviScan-3 system to predict the longitudinal modulus of elasticity (MOE) of small defect-free specimens. Longitudinal MOE was obtained from both bending tests and a sonic resonance technique. Overall, stronger relationships were found between the various measures of cellulose abundance and orientation and the dynamic MOE obtained from the sonic resonance measurements, rather than with the static MOE obtained from bending tests. There was only a moderate relationship between wood bulk density and dynamic MOE (R2=0.423), but this relationship was improved when density was divided by microfibril angle (R2=0.760). The best model for predicting both static and dynamic MOE involved the product of bulk density and the coefficient of variation in the azimuthal intensity profile (R2=0.725 and 0.862, respectively). The model parameters obtained for Sitka spruce differed from those obtained in earlier studies on Pinus radiata and Eucalyptus delegatensis, indicating that the model might require recalibration before it can be applied to different species. [ABSTRACT FROM AUTHOR]

The water vapour sorption behaviour of Sitka spruce was analysed based on the parallel exponential kinetics (PEK) model. The PEK model deconvolutes the sorption kinetics curve into two exponential kinetics processes (fast and slow) which have characteristic times and moisture contents associated with them. The sorption kinetics was examined at different temperatures enabling the determination of activation energies for the sorption kinetic processes throughout the hygroscopic range (from 5% to 95% relative humidities). The physical interpretation of the PEK model is also discussed. [ABSTRACT FROM AUTHOR]

AbstractMode I and Mode II initiation fracture toughness was examined by DCB (double cantilever beam) and 3ENF (three-point bend end notched flexure) tests on specimens of compressed Sitka spruce. The compressed wood was fabricated by varying the compression ratio, and the effectiveness of the compression treatment was examined in view of improving the fracture mechanics properties. In both cases, the fracture toughness did not show a significant increase after the compression treatment. Thus, it would be necessary to develop a new compression treatment method to improve the fracture mechanics properties. [ABSTRACT FROM AUTHOR]

The object of this study was to measure basic wood properties when water in wood is lost by heating under high temperature and high humidity. Using Sitka spruce ( Picea sitchensis Carr.) specimens with dimensions of 110 mm (R)×25 mm (L)×8 mm (T), temperature and weight were measured and free-free flexural vibration tests were conducted in water vapor at 115–150°C and 75–98% relative humidity. The results were compared to those at high temperatures without humidity control under atmospheric pressure. Early in the drying process, the resonance frequency and loss tangent showed a minimum and maximum, respectively. Temporal changes in the temperature, moisture content and vibrational properties were similar to those in heating without humidity control, while the specific Young's modulus and loss tangent during the drying processes were much smaller and greater, respectively, than those in heating without humidity control. Hence, we concluded that the wood was remarkably softened by high temperature and moisture. [ABSTRACT FROM AUTHOR]

Changes in the moisture content of green sitka spruce (Picea sitchensis Carr.) during heating in environments of over 100 C and 1 atm were measured. Temperature and weight were measured in a highly accelerated stress test (HAST) chamber. The set temperature and relative humidity ranges were 107160 C and 7599%, respectively. The change in the temperature of a specimen was roughly divided into 4 steps. Equilibrium moisture contents at lower temperatures and pressures were similar to previous estimates, while at higher temperatures and pressures they were higher than previous results.A diagram of temperature relative humidity pressure equilibrium moisture content in the range of 105160 C, 7599% RH and 0.020.39 MPa was obtained experimentally. [ABSTRACT FROM AUTHOR]

Abstractβ-1-4-Galactan has been detected in Sitka spruce [Picea sitchensis(Bong.) Carrière] by an immunofluorescence procedure. The anti-β-1-4-galactan monoclonal antibody LM5 was found to bind to compression wood (CW) tissue as identified by cell morphology features. In cross-sections, year rings with very fine bands of galactan-containing tissue were found. Cells in these bands expressed no morphological CW features. This finding was interpreted to imply that β-1-4-galactan synthesis is one of the first physiological reactions of CW formation. In cases where the CW character was pronounced, galactan was exclusively located in the outer cell-wall layers and was absent from the majority of the inner S2 layer. [ABSTRACT FROM AUTHOR]

AbstractThe spatial arrangement of polymers in Sitka spruce (Picea sitchensis) was investigated by NMR proton spin-diffusion studies, supplemented by deuterium-exchange experiments monitored by FTIR spectroscopy. The FTIR spectra of earlywood sections after vapour-phase exchange with deuterium oxide showed that 43% of the hydroxyl groups were accessible to deuteration. This value is lower than predicted in the absence of aggregation of cellulose microfibrils into larger units, but greater than the predicted level of deuteration if 3.5-nm microfibrils surrounded by hemicellulose sheaths were aggregated into 4×4 arrays without space for deuterium oxide to penetrate between the microfibrils. The rate of proton spin diffusion between lignin and cellulose was consistent with the presence of microfibril arrays with approximately these dimensions and with lignin located outside them, in both earlywood and latewood. Proton spin-diffusion data for hemicelluloses were complicated by difficulties in assigning signals to glucomannans and xylans, but there was evidence for the spatial association of one group of hemicelluloses, including acetylated glucomannans, with cellulose surfaces, while another group of hemicelluloses was in spatial proximity to lignin. These data are consistent with a number of nanoscale models for the Sitka spruce cell wall, including a model in which glucomannans are associated with microfibril surfaces within the aggregate and water can penetrate partially between these surfaces, and one in which all non-cellulosic polymers and water are excluded from the interior of each microfibril aggregate. [ABSTRACT FROM AUTHOR]