Оценка физико-механических свойств древесины сосны (Pinus sylvestris L.) ультразвуковыми преобразователями разной частоты

Currently, ultrasonic measurement is a widely used nondestructive approach to determine wood elastic properties, including the dynamic modulus of elasticity (DMOE). DMOE is determined based on wood density and ultrasonic wave velocity measurement. The use of wood average density to estimate DMOE introduces significant imprecision: Density varies due to intra-tree and intra-ring differences and differing silvicultural treatments. To ensure accurate DMOE assessment, we developed a prototype device to measure ultrasonic wave velocity with the same resolution as that provided by the X-ray densitometer for measuring wood density. A nondestructive method based on X-ray densitometry and the developed prototype was applied to determine radial and intra-ring wood DMOE profiles. This method provides accurate information on wood mechanical properties and their sources of variation. High-order polynomials were used to model intra-ring wood density and DMOE profiles in black spruce and jack pine wood. The transition from earlywood to latewood was defined as the inflection point. High and highly significant correlations were obtained between predicted and measured wood density and DMOE. An examination of the correlations between wood radial growth, density, and DMOE revealed close correlations between density and DMOE in rings, earlywood, and latewood

An IML-RESI PD 400 drilling tool and a standard spade drill bit were used to find the correlations of drilling and feeding resistance with the modulus of elasticity in static bending and density of wood. In total, 1575 drillings at 0.5, 1.0 and 1.5 m/min feed rates were made in specimens of Scots pine (Pinus sylvestris L.), European beech (Fagus sylvatica L.), English oak (Quercus robur L.) and common lime (Tilia europaea L.), which were oven-dried, conditioned at 20 °C/65% RH and 20 °C/95% RH and vacuum-impregnated with water. The feed rate (feed rate per major cutting edge or uncut chip thickness) had a significant impact on the prediction of density and modulus of elasticity through drilling resistance measurements and should be considered for comparison of properties and internal conditions of wood. Because of stronger correlation between drilling resistance and tested wood properties compared to feeding resistance, drilling resistance is recommended for density and MOE prediction of sound wood. Moisture content had no significant impact on the modulus of elasticity prediction by the drilling resistance measurements, while density can be predicted by linear models for two stages of moisture content variation, below and above fibre saturation.

Modulus of elasticity (MoE) is an important property of wood that can be assessed through both destructive and non-destructive testing (NDT) techniques. In this study, the suitability of non-destructive methods for estimating the dynamic MoE of clear-wood specimens of five hardwood species was investigated in green and dry conditions. Three vibration methods, viz. longitudinal vibration, flexural vibration and ultrasound method, were used to determine dynamic MoE, and values were compared with static MoE. The correlation between dynamic and static MoE was found to be statistically significant at a 0.01 significance level. The values for dynamic MoE in air dry conditions were observed to be higher than static MoE (22–42%), with the highest values observed for the ultrasound method (42%), followed by longitudinal vibration (33%) and flexural vibration (22%), respectively. Wood density was observed to be a strong factor influencing the mechanical properties of wood, particularly in dry conditions. However, in green condition, acoustic velocity (measured in longitudinal vibration and ultrasonic methods) was the predominant predictor of MoE. The findings of this study indicate that NDT can be used as a reliable and practical tool for estimating the MoE of wood in both dry and water-saturated conditions, offering a viable alternative to conventional testing methods.

This study explores the mechanical properties of hybrid eucalyptus wood, with a focus on dynamic and static moduli of elasticity (MOE), which is crucial for understanding the stiffness behaviour of wood. The research employs acoustic and static measurements on samples prepared from six trees sourced from Winneba and Amantia in Ghana. The results reveal significant variations in static and dynamic MOE, with higher static MOE observed in both Amantia and Winneba samples. However, Winneba and Amantia samples at the tree level were found to be insignificant statistically. The densities of the samples from the two locations, Winneba and Amantia, were found to be significantly different. Correlation studies revealed strong relationships between wood density and static MOE, as well as static and dynamic MOE, providing valuable insights into the comprehensive characterization of the eucalyptus globulus species grown in Ghana.

The aim of this paper was to predict the static bending modulus of elasticity (MOES) and modulus of rupture (MOR) of Scots pine (Pinus sylvestris L.) wood using three nondestructive techniques. The mean values of the dynamic modulus of elasticity based on flexural vibration (MOEF), longitudinal vibration (MOELV), and indirect ultrasonic (MOEUS) were 13.8, 22.3, and 30.9 % higher than the static modulus of elasticity (MOES), respectively. The reduction of this difference, taking into account the shear deflection effect in the output values for static bending modulus of elasticity, was also discussed in this study. The three dynamic moduli of elasticity correlated well with the static MOES and MOR; correlation coefficients ranged between 0.68 and 0.96. The correlation coefficients between the dynamic moduli and MOES were higher than those between the dynamic moduli and MOR. The highest correlation between the dynamic moduli and static bending properties was obtained by the flexural vibration technique in comparison with longitudinal vibration and indirect ultrasonic techniques. Results showed that there was no obvious relationship between the density and the acoustic wave velocity that was obtained from the longitudinal vibration and ultrasonic techniques.

The aim of this study was to determine relationships between selected properties of juvenile wood and characteristics of the stem and crown of Scots pine. Analyses were conducted in northern Poland on eight mature pine monocultures. Nine trees were selected in each experimental site and their stems were divided into five sections. The centers of the sections were established at a height of 1.3 m from the tree base and at points corresponding to 20, 40, 60 and 80% tree height. Samples were taken from these locations, and these samples were prepared for analyses of basic density, compressive strength along the grain and static bending, as well as the modulus of elasticity during bending. The mean height of the investigated group of trees was 26.0 m with an average diameter breast high of 33.6 cm. The mean crown depth was 7.8 m and crown diameter was 3.6 m, and the mean basic density (Qu) of juvenile pine wood was 416 kg/m3. The average compressive strength along the grain (CS) was determined to be 22.3 MPa, while static bending strength (BS) was 45.8 MPa. The recorded modulus of elasticity (MOE) was 4726 MPa. Both in general terms and when dividing stems into sections, the wood properties correlated with tree characteristics to various degrees. All indexes were negative indicating that trees of greater dimensions produce juvenile wood of inferior quality. Properties of juvenile wood formed during various periods of tree life were mostly related to diameter breast high and crown depth. They were also correlated with tree height, but only to a limited extent. In contrast, properties of wood from the middle stem sections were significantly correlated with crown diameter.

For a more efficient and rational use in the production of Scots pine wood of various geographical origin, it is necessary to know its physical and mechanical properties. The purpose of this study was to determine the physical and mechanical properties of wood of 17 climatic ecotypes of Scots pine and to carry out a comparative analysis of the indicators obtained for the studied climatypes separately and when they are grouped into subspecies in accordance with the classification of L.F. Pravdin. The range of the geographical origin of the places of seed procurement is from 47 to 62° north latitude and from 22 to 85° east longitude. The modern density universal testing machine MTS INSIGHT 100 was used for research. As a result of the research, it was found that the density of wood in an absolutely dry state varies from 370 kg/m3 (Kursk climatype) to 524 kg/m3 (Volgograd climatype), and at 12% humidity – from 397 kg/m3 (Kursk climatype) to 550 kg/m3 (Volgograd climatype). The index of the strength of wood of the studied climatypes for compression along the fibres was from 32 MPa (Kursk climatype) to 54 MPa (Volgograd climatype), and for static bending – from 55 to 92 MPa for the Vologda and Ulyanovsk climatypes, respectively. Distribution of Scots pine climatypes into subspecies in accordance with the classification of L.F. Pravdin and the obtained data on the physical and mechanical properties of wood have a certain pattern. The maximum density of wood at 12% moisture is typical for the European Scots pine subspecies is 497±8 kg/m3 , the minimum value of this indicator for the Siberian Scots pine subspecies is 423±30 kg/m3 . An intermediate position is occupied by the subspecies of Lapland pine and Forest-steppe pine with values of 483±16 and 464±12 kg/m3 , respectively. The strength index of wood in the studied subspecies for compression along the fibres ranged from 47±1 MPa (European subspecies) to 33±4 MPa (Siberian subspecies), in the Lapland pine subspecies – 44±2 MPa and somewhat lower in the Forest-steppe pine subspecies – 42±2 MPa. The maximum value of the static bending strength of wood is typical for the European pine subspecies – 78±4 MPa, and the minimum – for the Siberian pine subspecies – 61±14 MPa. This indicator turned out to be equal in subspecies of forest-steppe and Lapland pine and amounted to 72±4 MPa. The practical value of the work lies in identifying the existing differences and variability among climatypes according to the studied physical and mechanical properties of wood and selecting the most promising of them for further breeding purposes

Wood quality traits are important to balance the negative decline of wood quality associated with selection for growth attributes in gymnosperm breeding programs. Obtaining wood quality estimates quickly is crucial for successful incorporation in breeding programs. The aims of this paper are to: (1) Estimate genetic and phenotypic correlations between growth and wood quality attributes, (2) Estimate heritability of the studied traits, and (3) Assess the accuracy of in situ non-destructive tools as a representative of actual wood density. Wood density (X-ray densitometry), tree height, diameter, volume, resistance drilling, acoustic velocity, and dynamic modulus of elasticity were estimated, along with their genetic parameters, for 1,200, 20-year-old trees from 25 open-pollinated families. Individual tree level heritabilities for non-destructive evaluation attributes were moderate ( $$ {\widehat{h}}_i^2=0.37-0.42 $$ ), wood density and growth traits were lower ( $$ {\widehat{h}}_i^2=0.23-0.35 $$ ). Favorable genetic and phenotypic correlations between growth traits, wood density, and non-destructive evaluation traits were observed. A perfect genetic correlation was found between resistance drilling and wood density (rG = 1.00 ± 0.07), while acoustic velocity and dynamic modulus of elasticity showed weaker genetic correlations with wood density (rG = 0.25 ± 0.24; 0.46 ± 0.21, respectively). This study confirmed that resistance drilling is a reliable predictor of wood density in western larch, while the weak genetic correlations displayed by acoustic velocity and dynamic modulus of elasticity suggest limited dependability for their use as fast in situ wood density assessment methods in this species.

Environmental conditions affect the natural weathering that leads to changes in wood characteristics. This study was conducted to evaluate physical and color changes and to predict changes in the mechanical properties of uncoated wood after outdoor exposure for 10 months (300 days). Five commercially important tropical wood species from Indonesia were used in field tests in this study, namely sengon or albizia (Paraserianthes falcataria), meranti or shorea (Shorea spp.), mahoni or mahagony (Swietenia spp.), teak (Tectona grandis), and merbau (Intsia spp.). Moisture content, wood density, and color change, as well as the ultrasonic wave velocity and dynamic modulus of elasticity, were evaluated every month. After 2 months of exposure (60 days), color totally changed (ΔE* > 12) for all species except merbau, which underwent changes in the fourth month (120 days). Wood became darker during the experimental period, with the exception of merbau wood, which became lighter by the end of 10 months. Shorea and teak were sensitive to color change as a function of the length of exposure. The wood species and length of exposure also significantly affected both ultrasonic wave velocity and dynamic modulus of elasticity.

The objective of this study was to examine the potential of stress wave velocity (SWV) as a rapid and non-destructive method to estimate the mechanical properties of Melia azedarach wood. The SWV, dynamic modulus of elasticity (MOEd), modulus of elasticity (MOE), modulus of rupture (MOR, bending strength) and density were determined on ninety 20 ⋅ 20 ⋅ 320 mm clear wood specimens, obtained from stems of three ten-year-old M. azedarach trees, and tested at environmental equilibrium in 20°C, 60 % relative humidity (a moisture content of approximately 12 %). There was a statistically significant (0.1 % level) but weak correlation (R2 = 0.23) between the SWV and MOE, but no statistically significant correlation was found between the SWV and MOR. Much better results for prediction of static properties of M. azedarach wood were obtained when SWV and wood density (WD) were used together through calculation of MOEd in the air-dry condition (MOE: R2 = 0.76, MOR: R2 = 0.47), although in the case of MOR a model based on WD alone is slightly better (R2 = 0.58), and WD is also almost as good as MOEd for predicting MOE. It is concluded that SWV coupled with WD can be employed as a predicting parameter to evaluate the mechanical properties of M. azedarach wood during the manufacturing process, although WD alone is also effective. The SWV alone would not be useful due to MOE being almost directly proportional to WD at this moisture content.

In a biological context, the mechanical properties as elasticity and strength of green wood, particularly as measured in the axial direction, influence the stability of trees against static loads (e.g., snow, ice, rain) and dynamic loads (i.e., wind). Extensive collections of data on mechanical properties are listed in three different catalogs edited in Canada, Great Britain, and the United States. A statistical analysis shows that the density of the wood is a major predictor for the mechanical properties as measured in axial direction. In this respect, conifers from temperate zones and deciduous trees both from temperate and tropical zones do not differ significantly from each other. A common, nearly linear relation between the modulus of elasticity and the density at 50% moisture content is found. Relationships between strengths in bending, compression, and shear and green wood density have ordinary least squares scaling exponents around 1.2, but can almost equally well be approximated by linear functions of wood density. Therefore, if the density of stem wood of a given tree is known from direct measurement and differs from the tabulated value, the values tabulated for mechanical properties can be corrected for by a simple rule of proportion. Pulling tests as tools for tree control are discussed with emphasis on how the method is based on the knowledge of the mechanical properties of green wood, and how wood density is measured.

Досліджено відмінності динамічного модуля пружності, коефіцієнта затухання та швидкості звуку хвилясто-завилькуватої деревини порівняно з прямоволокнистою деревиною ялиці білої. Графічно наведено варіацію досліджуваних показників у межах радіуса та висоти стовбура. У межах радіуса стовбура із хвилясто-завилькуватою структурою можна виділити два класи якості деревини, а саме: перший – периферійна деревина (40 % радіуса стовбура) та другий – центральна (ядрова) деревини. Структурне розміщення деревного волокна, зокрема хвилясто-завилькувате, істотно визначає фізико-механічні характеристики деревини та їх варіацію. Коефіцієнт затухання деревини змінюється: від 6 до 10 для хвилясто-завилькуватої деревини; від 12 до 14 для прямоволокнистої деревини. Встановлено прямолінійну залежність першого порядку між динамічним модулем пружності та об'ємною масою деревини. Збільшення об'ємної маси прямоволокнистої деревини зумовлює збільшення модуля пружності та описується рівнянням прямої (R²=0,69…0,72). Прямолінійна залежність між динамічним модулем пружності та щільністю хвилясто-завилькуватої деревини є інверсійною. Динамічний модуль пружності прямоволокнистої деревини знаходиться в межах від 5921 до 12995 Н∙мм-2, а хвилясто-завилькуватої деревини – від 5053 до 12393 Н∙мм-2.

There is a growing interest in improving wood properties through the appropriate selection of seed provenances within species. In this study, wood density and mechanical properties were investigated for Acacia mangium trees from six different provenances, planted in Quang Tri, Vietnam. Radial and among provenance variation in stress wave velocity (SWV), wood density (WD), dynamic modulus of elasticity (MOEd), modulus of rupture (MOR), and modulus of elasticity (MOE) were determined on a total of 480 small clear specimens (20 × 20 × 300 mm) cut from 30 trees (five per provenance). SWV and selected wood properties near the pith were significantly lower than those near the bark. Differences in all selected mechanical properties among provenances were significant. The highest static properties (MOR and MOE) were found for the Long Thanh provenance indicating its potential suitability for breeding programs in Vietnam focused on improving A. mangium wood quality. A high positive correlation coefficient was found between MOEd and MOE (r = 0.93, P < 0.001) and our results indicate that the stiffness of A. mangium can be predicted using stress wave method provided the density of measured element is known.

High planting densities in coniferous stands usually lead to advantageous wood properties with high yields for strength graded timber in sawmills. In timber design, however, the focus is on mechanical wood properties, as structural engineers rely on the characteristic values for strength, stiffness and wood density defined for the strength classes. Almost 700 Douglas-fir boards from plots with establishment densities of 1000, 2000 and 4000 trees per hectare were graded with different strength grading machines before the boards were finally tensile tested. Three existing models including both the functional relationship and the class limits were applied to the tensile strength prediction: Modelknot based on knot size and wood density, ModelEdyn based on the dynamic modulus of elasticity (Edyn) only and Modelknot,Edyn based on Edyn and knot size were used to calculate the indicating properties (IPs) IPknot, IPEdyn and IPknot,Edyn. The ratio of achieved and required characteristic values for strength, stiffness and wood density was calculated for various T classes according to the European standard EN 338:2016. The focus was on two questions: (1) Do the samples from different densities meet the characteristic values of the respective T classes? (2) How does the complexity of the grading model affect the characteristic values of sawn timber with raw material planted at different initial densities? The results showed that the stiffness and wood density requirements of the T class profile according to EN 338:2016 were met for boards of all initial densities. Boards from higher and highest densities always exceeded the strength requirements, by on average $+$16 per cent and $+$36 per cent, whereas boards from low establishment densities fell short of the strength requirements by on average −15 per cent. Grading of multiple classes in one run also influenced the characteristic strength value. Applying the strength class combinations T15/T9, the negative deviations from the required strength value of the lower class T9 improved for boards coming from plots with an initial stand density of 1000 trees ha−1 from −14 per cent to −13 per cent (Modelknot), from −12 per cent to −2 per cent (ModelEdyn) and from −10 per cent to $+$6 per cent (Modelknot,Edyn). The non-compliance of the characteristic strength values at low initial density was only in a few cases below the limit value required for the test (90 per cent). The relative distance between the characteristic values within the three densities, nevertheless, was high. Complex grading models resulted in both better yields and low deviations from the requirements.

The aim of this study was to determine some of the anatomical, physical, and mechanical properties of 35-year-old Pinus eldarica Medw. wood. For this purpose, 3 normal pine trees were randomly cut down from the Garagpas-Kelardasht site located in the northern part of Iran. Disks and logs of wood were cut at breast height. The testing samples were prepared along the radial axis from the pith to the bark to determine anatomical and physical properties such as annual ring width, tracheid length, oven-dry density, basic density, and volume shrinkage, and mature wood was used to measure mechanical strength characteristics such as static bending (MOE and MOR) and compression parallel to the grain. The results showed that the densities (oven-dry density and basic density) and volumetric shrinkage increased along the radial axis from the pith to the bark. With increasing cambial age, the values of length increased while the annual ring width decreased. The average density of the test sample (\rho_{12}) was 545 kg m^{-3}, the modulus of elasticity (MOE) was 7.21 GPa, the modulus of rupture (MOR) was 82.81 MPa, and the compression strength parallel to the grain was 52.18 MPa. The relationship between the wood density and strength properties was determined by regression analyses. It was found that there were strong relationships between density and MOR and compression strength parallel to the grain. However, the modulus of elasticity showed weak correlation with the wood density. The results of this research were compared with the other growing sites of pine trees in Iran. As a result of this comparison, it was observed that pine trees grown in Garagpas-Kelardasht and pine trees at other sites have different wood properties.