Tangential Faces Research Articles

Effects of horizontal-to-vertical stiffness ratio on the vibration characteristics of a two-mass vocal fold model

In order to evaluate the effects of stiffness ratio of vocal fold on three-dimensional behavior of vocal fold vibration, numerical simulations were performed by using a two-mass vocal fold model with different stiffness ratio of the horizontal and vertical direction. A ratio of the spring constants for the same direction were fixed, while it for the orthogonal directions was changed. To simulate the airflow through the glottis, the one-dimensional Bernoulli’s equation was solved with an equivalent circuit for the compressible flow propagation. The vocal fold shape was represented by a smooth shape with cylindrical masses and tangential faces. The flow separation point was estimated using the boundary layer theory. The results showed that overall fundamental frequency of the vocal folds increased with increasing horizontal stiffness, whereas the vertical stiffness changes had few effects on it. We also found that there were topical conditions in which fundamental frequency rapidly changed with a few changes in stiffness ratio. The stiffness ratio at that time was from 0.80 to 1.08. Before and after the change, there was difference whether the motion trajectory of mass was circular or linear. These results indicate that the vertical stiffness largely affects the oscillation modes of vocal folds.

Influence of anatomy on the adhesion performance of four wood species

The aim of this study was to evaluate the influence of anatomical characteristics on the adhesion performance of Vatairea sp., Paulownia sp., Aspidosperma populifolium and Tectona grandis wood. Specimens for anatomical, physical and mechanical analyzes were produced from tangentially oriented boards. The treatments were joint glued from pieces of the same anatomical orientation (radial and tangential), evaluated for shear strength and glue line failure. The Vatairea sp wood had the highest specific gravity (0.74 g cm-3) and the Paulownia sp (0.34 g cm-3) wood was smaller. Aspidosperma populifolium species showed the highest shear strength in the glue line in the tangential and radial faces. The anatomical variables with higher influence on the wood adhesion process were pith ray cells and especially fibers that exhibit the greatest correlation with the shear strength of the glue line.

Effect of Knots on Horizontal Shear Strength in Southern Yellow Pine

Knots are inevitable components found in wood that can adversely affect the mechanical properties of the lumber. The objective of this study was to investigate the effect of knots on the horizontal shear strength of southern yellow pine. Knot condition (sound/unsound) and shear plane (radial/tangential face) were studied as the factors of shear strength. The standard ASTM D143-94 (2014) was used to compare 120 pairs of clear shear blocks and shear blocks containing knots. Paired t-test results showed that regardless of the direction of the grain compared with the shear plane (perpendicular or parallel), sound knots increased the shear strength and the unsound knots decreased shear strength. Based on this study, the unsound knot volume was found to be a significant factor in decreasing the shear strength in the radial or tangential face direction. Furthermore, no significant relationship between the knot angle and shear strength was found. Shear failure occurred in the wood when an encased knot sample was tested and shear failure occurred in the knot when an intergrown knot sample was tested.

Determination of physical and chemical properties and degradation of archeological Japanese cypress wood from the Tohyamago area using near-infrared spectroscopy

Here, we evaluated the application of near-infrared (NIR) spectroscopy for estimating the degradation level of archeological wood samples from the Tohyamago area, the dendrochronological ages of which were also determined. The wood samples were radially cut from three logs obtained from the Tohyamago area. NIR reflectance spectra were measured from the tangential faces of air- and oven-dried wood samples using a Fourier transform NIR spectrophotometer. The second derivative spectra within the wavenumber range of 6400–5200 cm−1, in which the effect of moisture content in wood is suspected to be insignificant, showed a characteristic behavior with age. By comparing the second derivative spectral change in our wood samples with that in wood degraded by aging, thermal treatment, fungal attack, and lightning reported in the literature, we found that the second derivative spectra of wood samples from one log was similar to those of wood degraded by hygro-thermal treatment, whereas those of wood samples from another log was similar to those of wood degraded by brown-rot fungi. The physical and chemical properties of archeological wood were well predicted using a combination of partial least square regression analysis and NIR spectroscopy.

Movement of the cambial domain pattern and mechanism of formation of interlocked grain in Platanus

The orientation of splitting and uniting of rays, which served as an indicator of the orientation of morphogenic events occurring in cambium, was determined on series of veneers covering large tangential faces of <i>Platanus</i> trunks. It has been shown that cambium consists of orientational domains of Z- and S-type. They are perpendicular to, or slightly inclined with respect to, the trunk axis. Axial dimensions of domains are 8-28 cm. They move upward along the trunk, at a rate 6,5—12 mm, per radial mm of xylem porduced. Migration domain patterns are responsible for the formation of the interlocked grain.

Impacts of fiber orientation and milling on observed crystallinity in jack pine

Influences of fiber orientation and milling on wood cellulose crystallinity were studied using jack pine wood. The fiber orientation effects were measured by sampling rectangular wood blocks in radial, tangential, and cross-sectional orientations. The influence of milling was studied by analyzing the unsieved and sieved milled wood fractions (all <1,000 μm). Fiber orientation effect was manifested in both X-ray and Raman measurements and was dependent upon the orientation of the sampled wood blocks. In Raman, the observed crystallinity was similar between the blocks sampled on the tangential and the radial faces. However, the estimated values were 5.5 % lower compared to that measured in a powdered sample pellet. Moreover, in these sampling modes, the orientation of the block with respect to the direction of the electric vector of the laser made a difference only for the tangential mode of sampling. When a wood block was sampled on the cross-sectional face, the observed Raman crystallinity was 3.9 % higher from that of the pellet. The observed crystallinity did not significantly differ with change in sample orientation with respect to the electric vector direction. In contrast, the Segal-WAXS study of the blocks indicated that compared to the pellet, the estimated crystallinities in the radial, tangential, and cross-sectional sampling modes were 5, 2, and 11 % lower, respectively. This suggested that the radial and the tangential faces of the blocks can be used to estimate the crystallinity of wood. With regard to the effect of milling on Raman and Segal-WAXS estimates, the wood crystallinity did not depend upon the particle sizes of the fractionated samples and was similar to that of the original unfractionated ground wood.

Microfibril angle of Eucalyptus grandis wood in relation to the cambial age

The microfibril angle (MFA) of wood is an important feature, which helps to explain the physical and mechanical behaviour of wood in use. It has been little investigated for wood produced in Brazil, mainly for mature trees. Thus, the objective of this study was to analyze the MFA of Eucalyptus grandis at age 25 years in relation to the cambial age. One disk was cut from the base of the stem from each of three trees, where growth rings were marked. From a central strip 3,0 cm wide, 1 cm3 blocks were removed from each growth ring. After sectioned on the tangential face with a sliding microtome, sections of 8 μm thick were macerated. The individual fibres were observed by polarized light microscopy for measurement of MFA. According to the results, i) the MFA decreased from 29,3° (ring no 1) to 18,9° (ring no 25); ii) MFA can be estimated by the cambial age – a, according to the equation MFA = 28,1 – 0,35 × a, with R2 = 94,7%.

Enhancing the applicability of near infrared spectroscopy for estimating specific gravity of green timber from Eucalyptus tereticornis by developing composite calibration using both radial and tangential face of wood

Specific gravity is a very important factor in determining the economics of wood and wood products. This study is aimed to apply the near infrared spectroscopy technique with integrating sphere and fiber optic probe accessories for fast prediction of specific gravity of green timber (moisture content 27–30 %) of Eucalyptus tereticornis from 10 to 12 year old plantation. Specific gravity (basic density) was determined by conventional method (oven dry wt/green volume) and correlated with near infrared spectra using partial least square (PLS) regression. Calibrations using radial face, tangential face and composite face (both radial and tangential) were developed and compared. Coefficient of determination of cross validation (\( {\text{r}}_{\text{cv}}^{ 2} \)) for radial-longitudinal, tangential-longitudinal solid strips samples and composite face (both radial and tangential) was between 0.74–0.77 and 0.64–0.77 using integrating sphere and fiber optic probe, respectively. The coefficient of determination of prediction (\( {\text{r}}_{\text{p}}^{ 2} \)) was between 0.73–0.85 (with integrating sphere) and 0.69–0.83 (with fiber optic probe). The ratio of performance deviation (RPD) ranges from 2.06 to 2.46 for all models. Root mean square error of prediction (RMSEP) was higher than root mean square error of cross validation (RMSECV). For composite models with radial and tangential face \( {\text{r}}_{\text{cv}}^{ 2} \)/\( {\text{r}}_{\text{p}}^{ 2} \) was 0.74/0.76 using integrating sphere and 0.71/0.83 with fiber optic probe with Quant 2 automatic factors optimization process. The results indicate that the composite model is just as good as the radial and tangential face models and can adequately address the problem where it is difficult to obtain perfect radial or tangential surface, particularly in small girth plantation timber or where surface recognition is difficult.

Development and evaluation of models for specific gravity of Eucalyptus tereticornis wood by fourier transformed near infrared spectroscopy and partial least squares regression analysis

Specific gravity is very important factor in determining the economics of wood and wood products. This study is aimed to apply the near infrared spectroscopy technique with integrating sphere accessory for fast prediction of specific gravity of dry timber (moisture content 12 %) of Eucalyptus tereticornis from varying age group. Specific gravity was determined by conventional method and correlated with near infrared spectra using partial least square regression. The coefficient of determination of cross validation (R cv 2 ) is in the range of 0.80–0.91 for radial face and 0.88–0.94 for tangential face. The calibration equations when applied to test set resulted in coefficient of determination (R TS 2 ) ranging from 0.68 to 0.93 for radial face and 0.90 to 0.94 for tangential face. The ratio performance of deviation was calculated as the ratio of the standard deviation of the prediction set to the root mean square error of prediction and it was found to be between 2.1 and 3.8 for radial face and 3.2–4.1 for tangential face. The values were found identical when groups i.e., calibration and test set were interchanged. The range error ratio for both faces models were also identical and indicating that models are quite satisfactory for screening purpose.

Estimating mechanical properties and specific gravity for five-year-old Eucalyptus tereticornis having broad moisture content range by NIR spectroscopy

Abstract Near infrared spectroscopy coupled with multivariate data analysis has been used to predict the specific gravity, modulus of rupture, modulus of elasticity, and fiber stress at elastic limit in bending tests on radial and tangential strip wood samples obtained from five-year-old Eucalyptus tereticornis. Moisture content of samples was 6–21% for bending test and 7–16% for specific gravity. Partial least squares regression calibrations were developed for each wood property. Calibrations had good relationships between values measured in laboratory and NIR predicted values obtained from small clear samples. The coefficient of determination (R2) for calibration ranged from 0.76 to 0.83 and for prediction (Rp 2) it was between 0.58 and 0.77. Both radial and tangential faces are equally suited for calibration (for radial face R2 was 0.77–0.83 and for tangential it was 0.76–0.83). Standard errors of predictions were slightly higher compared to standard error of calibration.

Anatomical features that facilitate radial flow across growth rings and from xylem to cambium in Cryptomeria japonica

Although the lateral movement of water and gas in tree stems is an important issue for understanding tree physiology, as well as for the development of wood preservation technologies, little is known about the vascular pathways for radial flow. The aim of the current study was to understand the occurrence and the structure of anatomical features of sugi (Cryptomeria japonica) wood including the tracheid networks, and area fractions of intertracheary pits, tangential walls of ray cells and radial intercellular spaces that may be related to the radial permeability (conductivity) of the xylem. Wood structure was investigated by light microscopy and scanning electron microscopy of traditional wood anatomical preparations and by a new method of exposed tangential faces of growth-ring boundaries. Radial wall pitting and radial grain in earlywood and tangential wall pitting in latewood provide a direct connection between subsequent tangential layers of tracheids. Bordered pit pairs occur frequently between earlywood and latewood tracheids on both sides of a growth-ring boundary. In the tangential face of the xylem at the interface with the cambium, the area fraction of intertracheary pit membranes is similar to that of rays (2.8 % and 2.9 %, respectively). The intercellular spaces of rays are continuous across growth-ring boundaries. In the samples, the mean cross-sectional area of individual radial intercellular spaces was 1.2 microm(2) and their total volume was 0.06 % of that of the xylem and 2.07 % of the volume of rays. A tracheid network can provide lateral apoplastic transport of substances in the secondary xylem of sugi. The intertracheid pits in growth-ring boundaries can be considered an important pathway, distinct from that of the rays, for transport of water across growth rings and from xylem to cambium.

Use of a simple abrasivewear resistance test device to assess the suitability of selected hardwoods for wood flooring

Indigenous hardwoods off‑cuts generated by most mobile sawmillers are usually discarded resulting in under utilisation of timber and reduction of profit margins. The traditional indigenous species used in wood flooring have poor regeneration and slow growth thus cannot indefinitely sustain fast harvesting rates. Equipment required to assess the suitability of wood for specific applications is not readily available in Zimbabwe, so a simple abrasive‑wear resistance test device was used as an alternative. The device can be constructed in any wood technology laboratory equipped with basic machine tools. Hardness and abrasive‑wear resistance tests were performed on the radial and tangential faces of selected hardwoods to assess their performance in wood flooring. The results showed slightly higher hardness on the tangential face in poplar and mahogany only and that hardness increased with wood density. This study showed that neither the hardness value nor wood density can sufficiently explain increased abrasive-wear resistance because this is controlled by certain compounds found in wood cavities. However, ranking of selected hardwood species into different wood flooring traffic classes was similar for hardness values and abrasive‑wear resistance indices. This illustrated the potential for using abrasive‑wear resistance tests device as an alternative technique. Successful use of this device may assist in the identification of alternative species, relieve pressure on commercial indigenous species and facilitate collection of performance data and other wood species suitable for wood flooring. Key words: Hardness value, abrasion‑wear resistance index, basic wood density, wood flooring.

Application of near Infrared Spectroscopy for Estimating Wood Mechanical Properties of Small Clear and Full Length Lumber Specimens

Near infrared (NIR) spectroscopy, coupled with multivariate analytic statistical techniques, has been used to predict the mechanical properties of solid wood samples taken from small clear and full length lumber specimens of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi). The specific mechanical characteristics evaluated were modulus of elasticity (MOE), modulus of rupture (MOR) in bending tests, maximum crushing strength in compression parallel to grain (CS), dynamic modulus of elasticity of air-dried lumbers (Efr), and wood density (DEN). Partial least squares (PLS) regression calibrations were developed for each wood property. The calibrations had relatively strong relationships between laboratory-measured and NIR-predicted values in small clear specimens, with coefficients of determination ranging from 0.61 to 0.89. The calibration models were applied to the prediction data sets and results suggested that NIR spectroscopy has the potential to predict mechanical properties of small clears with adequate accuracy (standardised prediction error=2.06-2.82). The PLS models based on spectra from the radial face ( R2 = 0.73-0.89) of wood were slightly superior to those from the tangential face ( R2 = 0.61-0.84). This might be due to the differences of the surface condition in terms of the anatomical structures and, thus, radial face better represents the sample. A reasonable predictive model for wood stiffness was also obtained from the full length lumber specimens, but the accuracy of the calibration for prediction was less than the small clear specimens ( R2 = 0.49-0.78). The regression coefficients obtained from the PLS models showed similar trends in all mechanical properties. It was suggested that the absorption bands due to the OH-groups in cellulose were the major contributors to building robust models for predicting the mechanical properties of wood

Effect of drying method on the surface wettability of wood strands

An experiment was conducted to investigate the effects of drying methods, namely rotary drum, lab oven, microwave and air-drying, on the surface wettability of wood strands by the Wilhelmy plate method. The measurements included the surface contact angle, free energy, and liquid sorption capacity. Thirty industrial strands including southern yellow pine (Pinus spp.) and poplar (Populus spp.) were randomly collected for each drying method. The results from this study showed that the surface contact angle of a strand depends on the liquid used as well as the drying method and wood species. Liquid sorption capacity of the pine strands increased with decreasing surface contact angle, but this trend was not observed with the poplar strands. The total surface energy was almost the same for strands within species, regardless of the drying method, but it was higher on poplar strands than on pines. The polar and disperse components of surface free energy varied with both drying method and wood species. The surface polar energies of oven-dried pine strands and rotating drum-dried poplar strands were higher than on strands dried by other methods. For lower temperature drying methods (air and microwave), the lowest polar component was observed on the radial face of the pine strands. For the higher-temperature drying methods (oven and rotary-drum), the lowest polar component was found to on the tangential face of the pine strands.

Effective non-destructive segregation of Eucalyptus grandis logs according to radial and tangential hardness

SummaryBasic density and hardness strongly influence the quality of high—value end products, such as floor boards. Significant variations in wood properties have been identified both within and amongst logs of plantation-grown Eucalyptus grandis (flooded gum or rose gum), which typically feature an inner cylinder of corewood characterised by low wood density, hardness and strength. These and other defects near the core are not easily detected until the log is sawn open and thus committed to a particular end-use. Despite this, it is important that only logs with suitably dense and hard wood in the core are processed into high-quality flooring.This study assessed the utility of a non-destructive tool, the Pilodyn, for gauging the radial variation in density and hardness amongst plantation-grown E. grandis logs prior to sawing. Pilodyn readings were taken at intervals across the ends of 40 typical fresh flooded gum logs about 5 m long. A sub-sample of 15 logs, representative of the Pilodyn penetration (P-pen) spectrum, was selected for more intensive testing. Janka hardness tests on air-dried specimens indicated characteristically low hardness (<3 kN) in the inner zone of every log. However, Janka hardness in the outerwood was found to be highly variable amongst logs. The segregation of logs into classes of P-pen readings (low, medium and high) provided a useful basis for predicting Janka hardness values: the correlation between the weighted average P-pen reading and weighted average Janka hardness was 0.80 and 0.81 for hardness on the radial and tangential faces respectively. Within each of the Pilodyn classes, the bending stiffness and strength, and compression strength parallel to grain of the timber, increased in the radial direction.Pilodyn tests on the end face of logs may assist processors to identify those logs with particularly problematic proportions of corewood and/or quality.

Effect of compression wood and grain angle on deformations of studs from 22-year-old scots pine trees

The effect of compression wood, spiral grain and grain angle on deformations of studs from 22-yr-old Scots pine trees was studied. Spiral grain angle was measured on the mantle surface of logs and grain angle on the tangential faces of studs. Bow, spring and twist were measured on studs at green condition and at 18% and 12% moisture content. From each stud four 3 mm thick cross-sections were sawn. The compression wood content and its position within cross-sections were analysed using image analysis. For the short sections, located between cross-sections, bow and spring, but not twist, were significantly correlated with the amount and the position of the compression wood content. Twist was significantly correlated with spiral grain angle and grain angle. In conclusion, this study suggests that the compression wood content and its position within cross-sections have an effect on deformations such as bow and spring. It is however, evident that the spiral grain angle and the grain angle have a major effect on twist deformations.

Anatomy of the vessel network within and between tree rings of Fraxinus lanuginosa (Oleaceae)

The three-dimensional (3-D) arrangement of vessels and the vessel-to-vessel connections in the secondary xylem of the stem of the ring-porous hardwood tree Fraxinus lanuginosa were studied in series of thick transverse sections with epifluorescence microscope and confocal laser scanning microscope. Vessels were traced in sequential sections, and vessel networks were reconstructed in two segments of wood with dimensions of 2 × 1.4 × 21.2 mm(3) and 2 × 1.4 × 5.8 mm(3) (tangential × radial × axial). The arrangement of vessels and intervessel pits were visualized by scanning electron microscopy in low-density polyethylene microcasts and on exposed tangential faces of growth-ring boundaries. The vessels deviated from the stem axis in the tangential direction and, to a lesser extent, in the radial direction. Some neighboring vessels were twisted around each other. Vessels that appeared solitary in single sections were found to be sequentially contiguous with a number of other vessels, forming networks that extended in the tangential direction and across growth-ring boundaries. In the 21.2-mm wood block, all earlywood vessels at the growth-ring boundary made contact with latewood vessels in the previous tree ring. Within a growth ring however, only a single contact was observed between individual earlywood and latewood vessels. Densely arranged intervessel pits were characteristic in the regions where adjacent vessels made contact with each other. Such bordered pits were abundant in the tangential walls of vessel elements adjacent to growth-ring boundaries. Therefore, bordered pits appear to provide the pathway for the radial transport of water via the vessel network across growth-ring borders. Fiber-tracheids, observed as terminal cells in the tree rings, might also contribute to the apoplastic transfer of water across ring borders.

Observation of anisotropic water movement in Pinus radiata D. Don sapwood above fiber saturation using magnetic resonance micro-imaging

Magnetic resonance micro-imaging has been used to visualise the movement of water during the drying of Pinus radiata D. Don (radiata pine) wood samples of varying annual ring orientation and dimension. The drying process has shown a strong influence of annual ring orientation for thin boards with drying deviating from the classical core-shell model. Diffusion tensor micro-imaging shows the direction of greatest restriction to diffusion being in the transverse radial direction. Similarly, anisotropic values for T2 relaxation are observed, with values obtained when the transverse face is normal to the static magnetic field being higher than in the case when the radial or tangential faces are normal to the field.

HIGH TEMPERATURE DRYING FROM THE THREE PRIMARY ORTHOGONAL SURFACES OF LOBLOLLY PINE

While several permeability studies have been performed, little information is available on the flow of water in wood along its three orthogonal axes during high temperature drying. Much southern yellow pine construction lumber is dried at temperatures above 100°C, thus how water moves in wood is of concern. In this experiment individual Loblolly pine (Pinus taeda) sapwood cubes were coated on two of their three orthogonal faces (longitudinal, radial, and tangential) and the effect of this sealing on the drying rate was determined. From these cubes, drying rates from each of the three primary planes were determined. The free water movement/evaporation between the radial and tangential faces was not statistically different, while the longitudinal rate was approximately three times faster. In commercial practice, the faster longitudinal rate is negated by the very small portion of transverse surface area relative to total lumber surface area. This partially explains why end checking and moisture variation in high temperature dried southern yellow pine lumber are not significant causes of degrade. There was no statistically significant difference in permeability across the seasons tested.

Effects of Mixed-Mode and Crack Surface Convection in Rapid Crack Growth in Coupled Thermoelastic Solids

Two Green’s function problems for rapid two-dimensional steady-state crack growth governed by fully coupled (dynamic) linear thermoelasticity are analyzed. In Problem A, normal and in-plane shear line loads move on the insulated surfaces of a semi-infinite crack growing at a subcritical speed. Problem B involves only normal line loads, but crack surface convection is allowed. Problem A involves, therefore, mixed traction/displacement boundary conditions, while Problem B also exhibits mixed thermal boundary conditions. Robust asymptotic forms based on exact solutions for related problems reduce Problems A and B to coupled sets of integral equations. Both sets exhibit both Cauchy and Abel operators, but are solved exactly. The solutions show that Mode II loading couples the tangential crack face separation and discontinuity in crack-face temperature changes, while crack surface convection enhances thermal response, especially at large distances. [S0021-8936(00)03101-9]