Mechanical Properties of Wood
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Abstract
The mechanical properties presented in this chapter were obtained from tests of pieces of wood termed "clear" and "straight grained" because they did not contain characteristics such as knots, cross grain, checks, and splits. These test pieces did have anatomical characteristics such as growth rings that occurred in consistent patterns within each piece. Clear wood specimens are usually considered "homogeneous" in wood mechanics.
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The Mechanical Properties of Wood
Nature, 1915
Hardwoods Ash, white 0.371 0.440 0.684 0.360 0.059 0.051 Aspen, quaking 0.489 0.374 -0.496 0.054 0.022 Balsa 0.229 0.488 0.665 0.231 0.018 0.009 Basswood 0.364 0.406 0.912 0.346 0.034 0.022 Birch, yellow 0.426 0.451 0.697 0.426 0.043 0.024 Cherry, black 0.392 0.428 0.695 0.282 0.086 0.048 Cottonwood, eastern 0.344 0.420 0.875 0.292 0.043 0.018 Mahogany, African 0.297 0.641 0.604 0.264 0.033 0.032 Mahogany, Honduras 0.314 0.533 0.600 0.326 0.033 0.034 Maple, sugar 0.424 0.476 0.774 0.349 0.065 0.037 Maple, red 0.434 0.509 0.762 0.354 0.063 0.044 Oak, red 0.350 0.448 0.560 0.292 0.064 0.033 Oak, white 0.369 0.428 0.618 0.300 0.074 0.036 Sweet gum 0.325 0.403 0.682 0.309 0.044 0.023 Walnut, black 0.495 0.632 0.718 0.378 0.052 0.035 Yellow-poplar 0.318 0.392 0.703 0.329 0.030 0.019 Softwoods Baldcypress 0.338 0.326 0.411 0.356 --Cedar, northern white 0.337 0.340 0.458 0.345 --Cedar, western red 0.378 0.296 0.484 0.403 --Douglas-fir 0.292 0.449 0.390 0.374 0.036 0.029 Fir, subalpine 0.341 0.332 0.437 0.336 --Hemlock, western 0.485 0.423 0.442 0.382 --Larch, western 0.355 0.276 0.389 0.352 --Pine Loblolly 0.328 0.292 0.382 0.362 --Lodgepole 0.316 0.347 0.469 0.381 --Longleaf 0.332 0.365 0.384 0.342 --Pond 0.280 0.364 0.389 0.320 --Ponderosa 0.337 0.400 0.426 0.359 --Red 0.347 0.315 0.408 0.308 --Slash 0.392 0.444 0.447 0.387 --Sugar 0.356 0.349 0.428 0.358 --Western white 0.329 0.344 0.410 0.334 --Redwood 0.360 0.346 0.373 0.400 --Spruce, Sitka 0.372 0.467 0.435 0.245 0.040 0.025 Spruce, Engelmann 0.422 0.462 0.530 0.255 0.083 0.058
Influence of biotic factors on the mechanical properties of wood, taking into account the time of harvesting
Wood Material Science & Engineering, 2015
The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.
Wood Research at the University of Sopron – Physical-mechanical Properties
E3S web of conferences, 2024
This study series shows research fields and results in wood science of the University of Sopron, Hungary. In this paper, we review several studies regarding the physical-mechanical properties of wood, including some properties of Turkey oak grown in different stands, showing that it should be planted among other species in same stand to achieve optimal wood quality. Research in the field of the firewood plantations has shown that it is necessary to choose the right species of poplars, in a given area. Paulownia and some invasive species grow rapidly, so they have great potential as raw materials and there are significant differences between paulownia varieties. Based on their densities, box elder, tree of heaven and green ash can be substituted for the noble species. Basswood can be well impregnated with paraffin, making it a good choice for pencils. Low-quality noble oak logs have the potential to be used in structural elements as lamellae, improving the yield and decreasing the loss in the wood industry. Black locust, sessile oak, beech, poplar, larch and spruce were subjected to different mechanical test methods at different moisture contents. Their properties decreased with increasing moisture content between 12% moisture content and FSP for all six wood species, but the ratio of changes varied, depending both on the measurement method and on the species.
Mechanical properties of the most common European woods: a literature review
Frattura ed Integrità Strutturale
Wood is an orthotropic material used since ancient time. A literature research about the mechanical properties of density, fracture toughness, modulus of elasticity, and Poisson’s ratio has been done to have a broader view on the subject. The publications relating to the topic were found through the two search engines Scopus and Google Scholar that have yielded several papers, including articles and book sections. In general, there is no standardization on the method of analysis carried out on wood, underlining the great difficulty in studying this complex material. The parameter of density has a great variability and needs a deeper investigation; fracture toughness is not always available in literature, not even in the different directions of the wood sample. Interesting is the modulus of elasticity, which provides a correlation with density, especially in longitudinal section but, again, it needs to be studied in detail. The parameter of Poisson’s ratio is provided as single value...
Study of Physical and Mechanical Properties of Post-Consumer Wood of Different Age
Deleted Journal, 2023
It should be noted that there is currently a problem with wood resources in the woodworking industry. A potential, unused wood reserve is post-consumer wood (PCW). The problem with the quality of this wood resource has not been fully resolved since there is no regulatory database. In fact, there is a lack of appropriate regulatory documents, which makes it impossible to describe to a full extent the physical and mechanical properties of PCW of common wood species of different ages as a source of additional raw materials for various woodworking technologies. Proceeding from the goal, the task of the study is to describe the physical and mechanical properties of postconsumer wood using the example of fir wood, which for a long period of time has been used to create furniture and joinery products. The task is also to identify patterns of change in the indicators of this resource with age -an expired service life or suitability. In order to use PCW in woodworking and to fill the scientific base with physical and mechanical indicators of fir wood of different ages with an expired product service life, the following characteristics were investigated: static hardness, swelling, coefficients of swelling, the value of transverse anisotropy, density, static bending strength, splitting strength along the fibers, modulus of elasticity in compression, and the modulus of elasticity in static bending. The characteristics of PCW of the widespread fir species in the range of use from 0 to 20 years were explored, with intermediate control over the properties every 5 years.
Annals of Warsaw University of Life Sciences. Forestry and Wood Technology No 73
2011
This study was carried out to evaluate the strength of the three most frequent joints in the upholstered furniture frames, made of beech and poplar solid wood. The research included the following joints: Mortise and Tenon, double Dowel and double Gusset Plates, which were constructed and tested both in corner and middle joints. In the corner joints we examined the compression strength of the joints and in the middle joints the tension strength was thoroughly investigated. The results of the bending (compression) test indicated that bending strength values of the four different joints were strongly correlated to tension strength values of the corresponding joints, whether they were constructed with beech or poplar wood. Also, a correlation was noticed between the bending strength values of the joints constructed with beech and the bending strength values of the respective joints made of poplar wood. Relative to tension strength values, a strong relationship was also recorded between ...
Physical and Mechanical Properties of Young-Growth Douglas-Fir and Western Hemlock from Western Washington
Forest Products Journal, 2009
Diversity in land management objectives has led to changes in the character of raw material available to the forest products industries in the US Pacific Northwest. Increasing numbers of logs from small-diameter trees, both plantation grown and those from suppressed or young stands, now constitute a large proportion of logs coming into the mill yard. Wood coming from plantations or young stands has different properties than wood coming from older, suppressed stands. This research examined wood properties of small-diameter plantation-grown Douglas-fir and western hemlock with the goal of a better understanding of utilization of small-diameter, fast-grown trees for use in manufacturing engineered wood composites. Twelve trees of each species were harvested and three bolts cut from each tree. Each bolt provided samples for X-ray densitometry profiles, compression, and tension parallel to grain and flexure tests. Both species were found to have a very high proportion of juvenile wood. Most wood properties decreased with increasing vertical position and increased with increasing distance from pith for both species. Increased competition for wood fiber, which accounts for as much as 25 to 35 percent of total wood composite (such as particleboard, medium-density fiberboard and oriented strand board) manufacturing costs, necessitates an understanding of raw material properties and their variations. This knowledge could assist in optimizing the manufacturing process and maximizing efficiency of wood raw material use, thus increasing profits.
Application of strength criteria in describing modified wood
The study was carried out on a series of 360 samples of Scots pine wood (Pinus sylvestris). A part of them were in their natural state, but the majority of them were superficially polymerized with poly(methyl acrylate). The test specimen comprised natural and modified wood with varying poly(methyl acrylate) (PMM) contents. The samples were tested for tensile strength on a universal testing machine. The purpose of the experiment was to examine the ways, in which polymerization improves on the strength properties and how the properties of materials change if the angle α between the load direction and the fiber orientation changes. An additional purpose of the study was to select an adequate strength criterion to describe the tested composite materials. Samples made of modified wood were uniaxially stretched at an angle of α = 0, 15, 30, 45, 60 and 90 ⁰ , measured between the direction of the load and the longitudinal direction of the fibers. It was claimed that the higher the polymer contents, the better the strength properties of modified wood. The study proposed its own model, which describes the bending stiffness of modified wood.
Compressive and Bending Strength Variations in the Properties of Portuguese Clear Oak Wood
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Within-stem variation in the mechanical properties of Portuguese oak wood was analysed, considering different locations (three sites in the centre and north of Portugal—Site 1, Site 2, Site 3) and positions within the tree (two distances to pith—P1, P2). The study comprised compression parallel to the grain, bending strength and modulus of elasticity. Ultimately, this study aims at assuring the building of a body of knowledge on the technological quality and processing options for this species. The results showed for one provenance, Site 1, a significant effect of the distance to pith in the mechanical properties, which can be related to a different soil composition. For this provenance, a decrease in the compression and bending strength was verified from pith to bark. For the other provenances (Site 2 and Site 3), no effect was noticed. The overall behaviour showed noticeable correlations between the mechanical properties and density.
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The aim of the presented study is to determine the relationship between mechanical parameters of selected wood species (Carya sp., Fagus sylvatica L., Acer platanoides L., Fraxinus excelsior L., Ulmus minor Mill.) used for the production of hand tools and drumsticks and the grain deviation angle from the rectilinear pattern. Modulus of rupture (MOR), modulus of elasticity (MOE), elastic strain and work to maximum load (WML) in the three-point bending test were determined. The results obtained show that the values of all the mechanical parameters measured for hickory wood are higher than those obtained for domestic species. As the grain deviation angle from parallelism increases, the mechanical properties of all analyzed wood species decrease. The greatest influence of grain deviation angle on mechanical parameters was recorded for the work to maximum load values.
Tensile Properties Along the Grains of Earlywood and Latewood of Scots Pine (Pinus sylvestris L.) in Dry and Wet State
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Representativeness of wood biomechanical properties measured after storage in different conditions
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Obtaining representative values of green wood properties is essential for studies investigating the biomechanical aspects of tree development and ecology. Here we compare the biomechanical properties of wood stored in various conditions between their collection in the field and their measurement. The study was performed on a large sample of wood specimens from different tropical species and different location in the trees, representing a wide diversity in wood structures. Elastic and viscoelastic properties are measured on green wood, and measured again after storage in different conditions: immersion in cold water during various durations, storage in an ethanol solution with or without washing in water, and air-drying with or without re-hydration. The systematic and random errors induced by these storage methods are quantified. Storage in cold water is the best way to preserve wood native properties. Soaking in ethanol is a fair alternative regarding elastic properties, but induces a significant change in viscoelastic properties. Air-drying causes important and partly irreversible changes in mechanical properties. However, regarding elastic properties, this change is a systematic bias so that the airdried elastic modulus provides a good basis for comparative studies of green wood stiffness.
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Mechanical Properties of Earlywood and Latewood Sections of Scots Pine Wood
BioResources
The aim of this study was to determine the mechanical properties of earlywood (EW) and latewood (LW) sections of Scots pine (Pinus sylvestris L.) wood, and determine the relationship between calculated and measured values. The bending strength, modulus of elasticity in bending, and the tensile strength of EW and LW sections were determined. The mechanical properties were calculated using EW and LW mechanical properties and LW proportion. Also, mechanical properties were determined in standard size samples and compared to the calculated properties. In earlywood and latewood sections, the bending strength was 37.3 MPa and 93.9 MPa, the modulus of elasticity in bending was 1557.6 MPa and 3600.4 MPa, and the tensile strength was 58.6 MPa and 189.6 MPa, respectively. The results showed that the LW section had higher mechanical properties than those of the EW section for all of the measured mechanical properties. The calculated bending strength, modulus of elasticity, and tensile strength values were 53.3 MPa, 2133.7 MPa, and 95.5 MPa, respectively. The calculated bending strength and modulus of elasticity values were lower compared to the measured values, while the calculated tensile strength values were higher than that of the measured values.
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Wood is a complex and highly variable biological material formed to give the tree best possible conditions for sustaining life. Thus every piece of wood is possessed of unique qualities. The great ...
Report on the Investigation of Mechanical Properties of Structural Timber from Three Stands
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