Assess Wood Quality Research Articles

Non-Destructive Wood Analysis Dataset: Comparing X-Ray and Terahertz Imaging Techniques

Wood density measurement plays a crucial role in assessing wood quality and predicting its mechanical performance. This dataset was collected to compare the accuracy and reliability of two non-destructive techniques, X-rays and terahertz waves, for measuring wood density. While X-rays have been commonly used in the industry due to their effectiveness, they pose health risks due to ionizing radiation. Terahertz waves, on the other hand, are non-ionizing and offer high spatial resolution. This article presents a database of wood samples measurements obtained using both techniques, on the same 110 samples with a fine location of the measuring points, on a wide range of wood species (tropical and temperate ones) and densities, from 111 kg·m−3 to 1086 kg·m−3. The database includes X-ray and terahertz scans, sample dimensions, moisture content, and color photographs.

Effects of oil heat treatment on poplar wood properties: A pilot scale study

Pilot-scale oil heat treatment was conducted to enhance the quality of poplar wood obtained from a fast-growing plantation. Three target temperatures, namely 180, 190, and 200 ˚C, were chosen for the oil heat treatment process. Clear, small specimens were cut from the lumber, following the prescribed standards for assessing wood quality. Light microscopy revealed the ruptures and deformation of the wood cell wall as the treatment temperature increased. The volumetric swelling of the treated specimen decreased proportionally with the increase in treatment temperature. The impact of oil heat treatment on the mechanical properties of wood varied depending on the specific type of mechanical strength and processing temperature. The modulus of rupture, toughness, and hardness of the treated specimens drastically decreased at 200°C. However, the specimens treated at 200°C exhibited much lower mass loss during the fungal decay test. The results of the analytical test showed an increase in the crystalline cellulose content and thermal stability of the treated wood, due to the thermal degradation of hemicelluloses and amorphous regions of cellulose. Overall, it is concluded that oil heat treatment of poplar wood in the optimal temperature is an efficient approach to upgrade its quality with minimal reduction in mechanical strength.

An application of mixed-effects model to evaluate the role of age and size on radial variation in wood specific gravity in teak (Tectona grandis)

To test whether radial variation of wood specific gravity (WSG) is controlled by tree age or tree size in teak (Tectona grandis L.f) plantation trees, opposing different-length pith-to-bark strips which represents the differential lateral growth rate was compared using mixed-effects model which considers the heterogeneity of variances and dependency in the data to gain insight into the stochastic processes that govern the wood formation process. Various models were tested in devising an appropriate radial WSG model. Models that accounted for serial correlation in WSG data performed better than the simple structure that assumes zero correlation between measurements. The autoregressive plus random tree effect structure performed better in describing the radial variation pattern. The variability of the data related to random fluctuations during tree development and the wood formation process is modeled by the autoregressive parameter revealing the intrinsic complexity of wood formation. Since they cannot be attributed to observed factors, models should consider temporal or serial correlations when assessing wood quality. The results revealed that tree age is a decisive factor in controlling the WSG of wood, while tree size is statistically less important. Furthermore, the core wood production period varies with the growth rate. It is shown that the core wood area decreased with slow growth. Findings presented here appear to provide the first demonstration of radial variation in WSG with respect to growth rate and age for planted teak growing in Ghana.

ВЛИЯНИЕ МАКРОСТРУКТУРЫ НА ПЛОТНОСТЬ ДРЕВЕСИНЫ ДУБА

An individual process of staining of each trunk occurs as a result of the long-term presence of wood in the river soil without oxygen access. It consists in changing the structure and chemical composition of the wood. There are industrial reserves of this wood on the territory of the Russian Federation, in the floodplains of a number of rivers. One of the most important tasks at the extraction stage is the primary individual quality assessment of the trunk. One of the most effective diagnostic indicators for assessing wood quality can be the number of annual layers in one centimeter. This indicator correlates well with wood density. The purpose of the research is to establish the influence of the macrostructure of natural wood and stained oak wood, changes in the microstructure on its density. It was found that the density of stained oak wood, depending on the number of annual layers in 1 cm, is about 10% higher than that of natural wood, all other things being equal. The magnitude and nature of the decrease in density along the radius of the trunk is the same as in natural wood. It is about 20%. The performed studies will allow making an express analysis of the quality of each stained wood trunk at the stage of making a decision on the behavior of its extraction. This will significantly reduce the cost of logging and primary processing of stained oak wood

Properties of the northern red oak (Quercus rubra L.) wood determined by fractometric measurements - preliminary results

This study presents preliminary results of the basic properties of the northern red oak wood as well as the relationship between the properties of the core samples obtained on the live tree and the tested properties. The core samples 5 mm in diameter were extracted from the tree and used for determining the fractometer properties: compressive strength parallel to grain, radial bending strength and braking angle. Using descriptive statistics and multiple regression, the relationship between fractometric parameters and basic physical and mechanical properties of wood determined by destructive methods (wood density, compressive strength in parallel with fibers and bending properties (bending strength and modulus of elasticity). The obtained values of the examined properties of northern red oak are within the limits of the literature data. Statistical analysis has shown that radial bending strength cannot be used as a reliable fractometric parameter in assessing wood quality. On the other hand, the obtained results suggest that the relationship between the other two parameters (compressive strength parallel to grain and fracture angle) and the properties of the northern red oak wood can be successfully described using the multiple regression models (coefficient of determination ranged from 0.945 to 0.990).

Wood Quality Characterization of Sycamore Maple (Acer pseudoplatanus L.) and its Utilization in Wood Products Industries

This study quantified the physical and mechanical properties of sycamore maple (Acer pseudoplatanus L.) as a basis for assessing wood quality. The physical properties of oven-dry density, density at 12% MC, green density, basic density, longitudinal, radial, tangential and volumetric shrinkages were tested and the mechanical properties of bending strength, modulus of elasticity at bending, compression strength parallel to grain and compression strength in radial and tangential direction as well as of Brinell hardness on the cross, radial, and tangential section were determined. Five sycamore maple trees from Medvednica region were selected for the purposes of this research. The results were compared with known literature data on sycamore maple wood, beech wood from the same sight, and beech wood from Gorski Kotar region. For a better understanding of sycamore maple physiology, as well as for assessing the quality of wood products, the distribution of wood properties within the tree radius, from pith to bark, was investigated. There was a general bell shaped distribution, in the radial direction, in wood density, and mechanical properties of sycamore maple wood. Shrinkages decreased from pith to bark, except for tangential shrinkage with bell shaped pattern. All investigated wood densities of sycamore maple from Medvednica were similar to the findings of studies known in literature, as well as shrinkages, except for the lower longitudinal shrinkage. Investigated mechanical properties of sycamore maple wood were similar to the findings of studies known in literature, except for the lower bending strength and modulus of elasticity (MOE). Investigated sycamore maple indicated better dimensional stability than beech wood from two locations in the region, although it did not match the beech wood regarding mechanical properties, especially wood hardness.

Assessing wood properties on hybrid poplars using rapid phenotyping tools

There is a growing interest in improving wood properties through clonal selection. However, traditional methods for determining wood properties are difficult to implement at the scale required for large-scale selection programs. In this study, we used rapid phenotyping methods (i.e., drill resistance (DR) and stress wave velocity (SWV)) for assessing wood quality in a 3-year-old clonal trial containing 125 clonal poplar hybrids. These hybrids belong to interspecific crosses of Populus deltoides [D], P. trichocarpa [T], P. nigra [N], and P. maximowiczii [M]. We estimated clonal variation and correlations among DR, SWV, basic density (BD), and dynamic modulus of elasticity (MOEd). Clonal repeatabilities were moderate for all traits, but were higher for BD and DR (i.e., R2 = 0.45 and 0.46, respectively) than for SWV and MOEd (i.e., R2 = 0.30 and 0.35, respectively). Clonal mean phenotypic correlations were high between BD and DR (rc = 0.84) and between SWV and MOEd (0.87), and the clonal correlations (rg) were 0.90 and 0.96, respectively. Overall, there was a weak relation between BD and MOEd (rc = 0.23 and rg = 0.29, respectively). Results support the use of DR and SWV as tools for the selection of poplar clones oriented to improve solid wood properties.

Preface

2019 Conference “Forests of Russia: policy, industry, science and education” was organised by Saint Petersburg State Forest Technical University and was held in Saint Petersburg, Russia from May 22 to 24, 2019.The volume contains articles based on the results of research in forest regeneration, forestry, forest inventory and management, forest protection, mechanical and chemical processing of wood and non-wood forest products, and forest law and economics. The results obtained in the course of research were discussed at the IV scientific and technical conference “Forests of Russia: Policy, Industry, Science, Education”, which was held on May 22-24, 2019 in St. Petersburg State Forest Technical University.The presented articles provide data on new methods for obtaining planting material for artificial forest regeneration and new ways of creating and caring for forest plantations. An assessment of the impact of various silvicultural measures on the productivity and quality of forests has been made. Existing methods of quantitative and qualitative assessment of forests have been analysed and new and more accurate methods for studying forests using unmanned aerial vehicles have been proposed. New methods for the identification of pathogenic microorganisms that affect the biological stability of forests have been proposed, and a technology has been developed to protect forests from pests. Fire safety of forests has been analysed and fundamentally new approaches have been proposed including preventive fireproof treatment of forests and the creation of fire-resistant breaks. Non-destructive methods to assess wood quality and fundamentally new methods of drying sawn timber have been discussed. New technologies of chemical processing of wood waste and forest products for the production of medicinal and agricultural products have been proposed. Existing methods of the economic assessment of forest stands and forest products have been analysed, and a method for their improved assessment has been developed. Forest legislation and forest relations in the Russian Federation have been analysed, and ways to optimise and improve them have been proposed.All published articles are of undisputable scientific and practical interest for scientists and specialists on forest, woodworking and wood chemical industry.I am very grateful to the authors of the published articles, and I would like to thank Ph.D. M. Lobovivikov, Professor A. Alekseev, Associate Professor E. Kuznetsov, Professor A. Chubinsky, Professor D. Ponomarev, Associate Professor I. Melnichuk, Professor V. Neshataev, and Associate Professor E. Khitrov for editing these articles.Vice-rector on scientific work,Candidate of Technical Sciences Vasily Gedyo

Nondestructive Evaluation of Corymbia citriodora Logs by Means of the Free Transverse Vibration Test

The bending modulus of elasticity has been used as a wood quality predictor due to the good correlation between bending stiffness and strength. In recent years, there has been an increasing use of nondestructive testing techniques based on dynamic tests to assess wood quality. The objective of this study is to evaluate the results obtained with the application of transverse vibration test to measure the bending modulus of elasticity of Corymbia citriodora logs. The approach used estimated the log cylinders with the diameter equal to the diameter measured at half-length. A sample of 38 C. citriodora logs was tested in free transverse vibration and static bending tests, their diameter measured at half-length ranged from 13.6 to 20 cm and the length ranged between 4 and 4.4 m. A strong correlation (\(\hbox {R}^{2} = 0.92\)) was found between static and dynamic bending modulus of elasticity. The transverse vibration test was faster than the static bending test. The results indicate that the free transverse vibration test provides accurate measurements of bending modulus of elasticity of C. citriodora logs.

Specific Structural Indexes for Resonance Norway Spruce Wood Used for Violin Manufacturing

The aim of this study was to assess wood quality using diagnostic keys related to the main traits of trunk architecture in the most important resource of resonance spruce of the Romanian Carpathians. The material sampled from standing and felled trees yielded 568 individual ring series adding up to over 81,000 growth rings. The resonance xylotype was first recognized in felled trees, already designated for violin manufacture, for which a 6-class quality classification system was proposed. This system was extended to the qualitative classification of the standing trees (diameter at breast height larger than 10 cm). The width and regularity of the growth rings, the width of the sapwood and latewood, and the compression wood ratio are the variables that make recognition of trees containing resonance wood possible. Wood with resonance structural value was detected locally along the tree stem, and the best resonance structural quality was found uniformly distributed from 5 to 9 m above the ground and in the external half of the cross-section. Trees having a proper structure for violin fliches, but not yet with an appropriate size (38 cm underbark diameter), accounted for about 7% of the total tree population.

Extractives and energetic properties of wood and charcoal

Charcoal production stands out as a raw material for the production of renewable energy. To assess wood quality in energy terms, studies have focused more on the holocellulose and lignin content than on the role of extractives. The objective of this study was to evaluate the relationship between the extractive content in cold water, in dichloromethane and total on energy properties of wood and charcoal, from six trees species. The extractives were removed with different solvents to be recorded and gross calorific value of wood was determined. The wood was carbonized at 1.67°C/min heating rate until maximum of 450°C and residence time of 30 min. The extractive content was correlated with the gravimetric yield, apparent relative density, ash, volatile matter, fixed carbon and gross calorific value of charcoal. The removal of total extractives and extractives soluble in dichloromethane reduced the gross calorific value of wood of most species evaluated. The extractives removed in cold water did not correlate with the parameters of carbonization. The extractives content in dichloromethane correlated with volatile matter, fixed carbon and gross calorific value. Total extractive content correlated with gravimetric yield, apparent relative density and gross calorific value of charcoal.

Assessing wood quality by spatial variation of elastic properties within the stem: Case study of Pinus pinaster in the transverse plane

The wood quality of maritime pine (Pinus pinaster Ait.) is discussed in view of spatial variability of density, annual growth ring characteristics, and transverse elastic properties within and among five basal logs. X-ray microdensitometry measurements are carried out to assess both average (Dmean) and local (DEW, DLW) densities of annual growth rings, as well as the respective dimensions (EWW, LWW) and fractions of earlywood (EW) and latewood (LW) layers. Mechanical tensile tests on a set of specimens with different ring orientation are proposed. Transverse elastic properties are determined by coupling an inverse identification strategy with full-field deformation measurements provided by digital image correlation. For a suitable range of off-axis angles, this method allows the simultaneous characterisation of the four orthotropic elastic properties in the RT plane: ER, ET, νRT, and GRT. These results are found in agreement with reference values. From the sampled specimens among logs, ER and GRT are robustly identified in all cases and therefore are selected for further analysis of structure-properties relationships. Correlations between Dmean and ER and GRT are positive and statistically significant. Furthermore, other parameters also show significant correlations with the elastic constants, especially Dmin, LWW, and DEW.

Methods for the very early selection of Pinus radiata D. Don. for solid wood products

There has been an increasing interest in very early selection of radiata pine to reduce the breeding cycle for solid wood products. For such selection, new approaches are required to assess wood quality in wood from very young stems. Nursery seedlings of clones of radiata pine were grown in leant condition using two leaning strategies for 18–20 months. Opposite wood and compression wood were isolated from the leaning stems and tested for dynamic modulus of elasticity, density, longitudinal shrinkage, volumetric shrinkage and compression wood area using new methods evolved for testing small size samples quickly and reliably. The methods were tested for their efficiency in differentiating clones by their wood properties. Leaning of stems provided distinct opposite and compression wood for testing. Automated image analysis method used for compression wood area assessment was found to be a quick and effective method for processing large number of samples from young stems. Compression wood was characterised by high basic density, high longitudinal shrinkage and low volumetric shrinkage than that of opposite wood. Acoustic velocity in opposite wood had a strong negative association with longitudinal shrinkage. The study signifies the importance of preventing mixing of opposite wood with compression wood while assessing wood quality in young stems thus making leaning a critical strategy. The comparison of wood properties of opposite wood revealed significant differences between clones. Opposite wood of the clone with the lowest dynamic modulus of elasticity exhibited the highest longitudinal shrinkage. Significant differences in measurable wood properties between clones suggest the prospects of early selection for solid wood products.

Ultrasound waves for assessing the technological properties of Pinus caribaea var hondurensis and Eucalyptus grandis wood

The forest sector plays an important role in the economy and, in these times of sustainability, industries need to save natural resources and leverage them as best as possible in order to achieve excellence in product quality and win the consumer market. The use of advanced technologies and improvement in pre-existing techniques is the most efficient way to understand the raw material, and improve the quality of products manufactured and their rational use. The use of nondestructive technologies has proven effective in characterizing and assessing wood quality. This work aims to predict certain physical and mechanical properties of Pinus caribaea and Eucalyptus grandis, using ultrasound. The research was conducted at the University of Brasilia (UNB), in conjunction with the Forest Products Laboratory (LPF/SFB) and the State University of Campinas (UNICAMP/SP). The results permit us to state that certain physical-mechanical properties of these species can be predicted with ultrasound. The property best estimated is density, followed by modulus of elasticity and modulus of rupture.

Variations in the radial growth and wood density components in relation to cambial age in 30-year-old Pinus brutia Ten. at two test sites

Radial growth and wood density are important traits in assessing wood quality. Our objective was to investigate patterns of variation of radial growth (ring width, earlywood width, latewood width, latewood proportion) and wood density (ring average density, earlywood density, latewood density) components in a 30-year-old Pinus brutia at two test sites in Turkey. Wood increment cores at a height of 1.30 cm (dbh) from 1,010 trees at age 30 years were evaluated at two test sites. The radial growth and wood density traits of the individual rings were measured using X-ray densitometry. The test sites showed statistically significant differences in the radial growth traits but not in the wood density traits, suggesting that the wood density traits are less subject to environmental changes. The ring average density was relatively low (485 kg/m3) at early cambial ages (near the pith) and increased to 501 kg/m3 at later cambial ages (near the bark). The latewood density was 550 kg/m3 near the pith, increased steadily to 630 kg/m3 at cambial age 12, and remained stable thereafter. In contrast, the earlywood density and latewood proportion were highest near the pith. The twelfth ring from the pith appeared to represent the transition from juvenile to mature wood. The unique relationships among early and latewood densities and latewood proportion in the juvenile and mature wood contribute to more uniform wood both within a given annual ring and between the juvenile and mature portions of the stem in P. brutia. Thinning increased the ring width, latewood proportion, and ring average density.

Wood quality in artificially inclined 1-year-old trees of Eucalyptus regnans — differences in tension wood and opposite wood properties

This paper presents a new approach to assess wood quality in 1-year-old Eucalyptus regnans F. Muell. Twenty-two seedlings were grown tilted to induce tension wood and acoustic velocity, basic density, longitudinal shrinkage, and volumetric shrinkage of both opposite wood and tension wood were assessed subsequently. Longitudinal growth strains were also estimated in the leaning stems by sawing along the length through the pith and measuring the bending of the two halves. The derived longitudinal growth strain, which varied from 708 to 2319 µε, was uncorrelated with stem and wood characteristics. Wood characteristics differed significantly between upper-side wood (predominantly tension wood) and lower-side wood (opposite wood). Tension wood was characterized by a higher acoustic velocity (high stiffness), basic density, and volumetric shrinkage compared with opposite wood. Tension wood also exhibited significant collapse and dimensional distortion such as twisting. Longitudinal shrinkage exhibited a significant negative relationship with acoustic velocity in opposite wood and a positive relationship with the basic density in tension wood. This new approach has potential in early selection of breeding material with superior normal wood properties from 1-year-old material by isolating the influence of tension wood. This approach can also be useful in understanding the variability in propensity of tension wood production in breeding populations.

Effect of Fire Charring on Condition of Ponderosa Pine Trees in Oregon as Measured by Longitudinal Compression Strength

Abstract The ability to assess wood quality using longitudinal compression strength (LCS) of plugs removed from along the length of a tree stem was assessed in ponderosa pine damaged to varying degrees 4 years earlier in a prescribed burn. LCS has been used elsewhere to estimate residual strength of utility poles and might be a simple method for assessing wood quality in standing trees. The degree of stem char on fire-killed trees had a significant effect on LCS values. LCS values of plugs from charred portions of fire-killed ponderosa pines were greater than those from uncharred portions of fire-killed ponderosa pine trees. LCS might be a useful tool for forest managers assessing the remaining flexural properties of standing dead timber after fires.

Wood Quality and Strength Properties of Old Structural Members

It is necessary to assess wood quality and strength of the clear specimens from used members in old wooden structures for the reuse of old members on the same structure or a new structure. Wood species classification by microscope observation of each wood member that was used in truss cord and temple, and several physical and strength tests by the specification of present KS standards were conducted to compare with some references. From the comparison of strengths with references, Korean larch gives relatively better wood quality and mechanical properties than other wood species. No significant deterioration of cell wall was found by microscopic observation for the sound wood part that was selected visually. Tensile specimens with 3 mm in thickness on the middle span showed greater strength than 5 mm thick specimens, which explains that dimension of tensile specimen should be examined for evaluating precise tensile strength properties. Other tests, compression, shear, and bending, are adoptable for each strength properties. Test methods for the evaluation of basic strengths and fastener connections for old wood species should be further examined.

Ultrasonic techniques for nondestructive testing of standing trees

The aim of this study is to assess wood quality of standing trees with ultrasonic velocity methods. The ultrasonic techniques currently used are: scattering based techniques that use travel time and other wave parameters for measuring the elastic constants of wood, and ultrasonic tomographic imaging techniques which seek to provide a high resolution picture of the defect. Scattering based techniques were firstly used as nondestructive techniques with increment cores of 5 mm diameter. On these specimens measurements with bulk waves––longitudinal and shear were used to detect the influence of sylvicultural treatment (pruning) on wood quality and also to detect defects (slope of grain, wavy figures). High resolution imaging techniques were developed for imaging abnormalities induced by biological attacks of fungi or insects in standing trees. In this case, ultrasonic tomography refers to cross-sectional imaging of trees from data collected by illuminating the tree from different directions. Ultrasonic images were reconstructed from the time of flight. The images were reconstructed from 120 measurements in situ and through the bark with direct transmission technique, using 1 MHz transducers. The resolution is 5 cm.

Evaluation of standing tree quality of Japanese cedar grown with different spacing using stress-wave and ultrasonic-wave methods

The quality of wood in 47-year-old standing trees of Japanese cedar grown in five plantation sites with different spacing (A, 1×1m; B, 2×2m; C, 3×3m; D, 4×4m; E, 5×5m) was evaluated using stress-wave and ultrasonicwave propagation methods. The magnitude of the velocities of these waves and the calculated dynamic modulus of elasticity (MOE) were used as indexes for assessing wood quality in standing trees. Results indicated that plantation spacings had moderate influence on the stress-wave and ultrasonic-wave velocities, and the degree of influence varied with the wave-propagating direction. Regardless of the testing method used, the velocities of waves propagated parallel to the grain in the standing trees with medium and poor growth conditions were significantly greater than those with superior growth conditions. The dynamic MOE of the trunk of standing trees of Japanese cedar was calculated by adjusting the effective mobility of free water and effective density in the trunk at various moisture contents. Results indicated that the dynamic MOE of wood in the standing trees of Japanese cedar was affected somewhat by the testing methods used. Furthermore, the dynamic MOE of the wood in the standing trees varied with the growth conditions imposed.