Black spruce trees from fire-origin stands have higher wood mechanical properties than those from older, irregular stands

2014 ◽  
Vol 44 (2) ◽  
pp. 118-127 ◽  
Author(s):  
Luciane Paes Torquato ◽  
David Auty ◽  
Roger E. Hernández ◽  
Isabelle Duchesne ◽  
David Pothier ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fixed Effects ◽  
Stand Structure ◽  
Black Spruce ◽  
Ring Width ◽  
Regular Structure ◽  
Modulus Of Rupture ◽  
Nonlinear Mixed Effects Models ◽  
Clear Wood ◽  
Cambial Age

In the eastern Canadian boreal forest, long fire return intervals lead to over 60% of stands having an irregular, uneven-aged structure, which is associated with slower growth. The aim of this study was to examine the effect of stand structure on the clear wood mechanical properties of black spruce (Picea mariana (Mill.) B.S.P.). A total of 128 trees were destructively sampled from stands of regular and irregular structure across Quebec, Canada. Nonlinear mixed-effects models were developed for each stand type to describe the variation in modulus of elasticity (MOE) and modulus of rupture (MOR) in small defect-free samples as functions of cambial age and annual ring width. Mechanical properties were strongly related to cambial age, with a smaller influence of ring width. After accounting for these variables, both MOE and MOR were higher in samples from stands of regular structure, although differences were less pronounced in the upper stem compared with breast height. The fixed effects of the models explained between 34% and 53% of the variation in mechanical properties. A higher incidence of mild compression wood in trees of layer origin may explain the observed differences between stand structures.

Modelling of tangential, radial, and longitudinal shrinkage after drying in jack pine and white spruce

2013 ◽  
Vol 43 (8) ◽  
pp. 742-749 ◽  
Author(s):  
Mingkai Peng ◽  
John A. Kershaw ◽  
Ying Hei Chui ◽  
Meng Gong
Keyword(s):  
Fixed Effects ◽  
Growth Ring ◽  
Ring Width ◽  
White Spruce ◽  
Wood Formation ◽  
Jack Pine ◽  
Longitudinal Shrinkage ◽  
Nonlinear Mixed Effects Models ◽  
Individual Tree ◽  
Cambial Age

The purpose of this study was to develop an understanding of the pattern of variation in longitudinal, radial, and tangential shrinkage in two commercially important Canadian wood species using multivariate nonlinear mixed-effects models. Shrinkage data were measured in each growth ring at different heights on trees harvested from a mixed-species Nelder tree-spacing plot located in New Brunswick, Canada. Live crown base was reconstructed based on stem analysis. Cambial age, sampling height, crown characteristics (crown length, crown ratio, and distance to live crown base), and ring width at time of wood formation were used as prediction variables. The results indicated that shrinkage magnitude and pattern were closely related to crown dimensions and stem position at time of wood formation. Trees from wider tree spacings with larger crown lengths and ratios tended to have smaller tangential and radial shrinkage. Longitudinal shrinkage decreased nonlinearly from pith outwards with slower rate changes near the bottom of the trees. The model fixed effects accounted for more variation in jack pine (Pinus banksiana Lamb.) than in white spruce (Picea glauca (Moench) Voss) for shrinkage in the same anatomical direction. After further validation, the model developed can be used to provide shrinkage predictions for lumber distortion models within the framework of an individual tree growth model.

scholarly journals Species, grading, and mechanical properties of locally sourced timber in the Joyabaj region of Guatemala

2019 ◽  
Vol 6 (2) ◽  
Author(s):  
Larissa Bogle-Boesiger ◽  
Todd Davis
Keyword(s):  
Mechanical Properties ◽  
Forest Products ◽  
Modulus Of Rupture ◽  
White Pine ◽  
Eastern White Pine ◽  
Clear Wood ◽  
Visual Grading ◽  
Wood Structures ◽  
Design Values ◽  
Multiple Species

The purpose of this project was to research the timber used by Engineers without Borders (EWB) groups in the Joyabaj region of Guatemala. This project aimed to investigate the species of wood, evaluate the quality by assessing the distribution of timber grades, and determine mechanical properties. The results will aid EWB groups in the design of wood structures in the Joyabaj region of Guatemala.Samples were collected for species investigation and mechanical testing. Species investigation was triangulated from interviews with the sawmill owner, construction foreman, testing by the USDA Forest Products Laboratory, and comparisons to literature. The results were inconclusive and indicated multiple species were intermixed at the sawmill with no distinction made when purchased. Timber quality was evaluated by using a visual grading guide developed by the authors to assess the distribution of grades within a large order of lumber. Static bending and compression parallel to grain tests were conducted to obtain modulus of rupture, compression parallel to grain, and modulus of elasticity. Specific gravity was also obtained.The results indicate that three different species were collected. Ninety per cent (90%) of the timber was No. 3 or better and 50% to 80% was No. 2 or better depending on the size. Clear wood testing values were similar to those of Eastern White Pine. Structural design should be performed based on National Design Specification (NDS) design values for a No. 3 or No. 2 Eastern White Pine, depending on the degree of wood selection in the construction process.

Predicting mechanical properties of clear wood from Acacia mangium provenances using ultrasound

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 8309-8319
Author(s):  
Doan Van Duong ◽  
Masumi Hasegawa
Keyword(s):  
Mechanical Properties ◽  
Compression Strength ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Significant Positive Correlation ◽  
Correlation Coefficients ◽  
Acacia Mangium ◽  
Longitudinal Direction ◽  
Modulus Of Rupture ◽  
Clear Wood

Ultrasound was considered as a means for determining mechanical properties of clear wood in six different Acacia mangium provenances from a trial forest planted in Vietnam. A total of 30 trees (5 trees from each provenance) with no major defects were selected, and a 50-cm-long log was obtained at 1.3 m above the ground from each tree for the assessment of mechanical properties. The measured average ultrasound velocities for provenances tested in the longitudinal direction ranged from 4094 m/s to 4271 m/s. The predicted average dynamic modulus of elasticity (Ed) values varied from 7.42 GPa to 8.70 GPa among provenances. The Ed indicated significant positive correlation coefficients with modulus of elasticity (0.64 to 0.96), modulus of rupture (0.44 to 0.87), and compression strength (0.54 to 0.92) for provenances examined in this study. The results indicated that the use of ultrasound was feasible to determine the mechanical properties of A. mangium provenances planted in Vietnam.

scholarly journals MECHANICAL PROPERTIES OF POLISH-GROWN PINUS SYLVESTRIS L. STRUCTURAL SAWN TIMBER FROM THE BUTT, MIDDLE AND TOP LOGS

Wood Research ◽  
2021 ◽  
Vol 66 (2) ◽  
pp. 231-242
Author(s):  
Sławomir Krzosek ◽  
Marek Grześkiewicz ◽  
Izabela Burawska Kupniewska ◽  
Piotr Mańkowski ◽  
Marek Wieruszewski
Keyword(s):  
Mechanical Properties ◽  
Pinus Sylvestris ◽  
Modulus Of Elasticity ◽  
Ring Width ◽  
Modulus Of Rupture ◽  
Bending Test ◽  
Average Growth ◽  
Growth Ring Width ◽  
Annual Growth Rings ◽  
Sawn Timber

The research consisted in testing Polish sawn timber dedicated for construction applications made of pines (Pinus sylvestris L.) that grew in the Silesian Forestry Region, taking into account three parts of the log: butt, middle and top. The boards had the same cross section, a nominal thickness of 40 mm and width of 138 mm, typical for Polish structural timber. The mean nominal length of the boards under research amounted to 3500 mm. Each set was composed of 70 boards. Before the tests, boards were dried in an industrial drier until reaching the moisture content of 12%, and they were planed on 4 sides. First of all, the sawn timber was graded into strength classes, and their dynamic modulus of elasticity (MOE_dyn) was tested with a non-destructive method, with the use of a portable MTG device. The next step consisted in a bending test with four points of support, according to the EN 408 standard, and with the use of the TiraTest 2300 machine, in order to determine the global modulus of elasticity (MOE_EN-408) and the static bending strength, also referred to as modulus of rupture (MOR). Finally, the average growth ring width was determined for each board (PN-D-94021), as well as wood density according to EN-408. The hereby paper presents the test results for all the tested sawn timber boards, taking into account the part of log that each board came from: butt, middle or top. The hereby paper presents the influence of density on the mechanical properties of wood, taking into account the location on the round timber. The analysis does not include the influence of the width of annual growth rings and the proportion of latewood on the wood properties under research.

Predicting selected wood properties of jack pine following commercial thinning

2008 ◽  
Vol 38 (7) ◽  
pp. 2030-2043 ◽  
Author(s):  
Robert Schneider ◽  
S. Y. Zhang ◽  
D. Edwin Swift ◽  
Jean Bégin ◽  
Jean-Martin Lussier
Keyword(s):  
Wood Density ◽  
Ring Width ◽  
Wood Properties ◽  
Jack Pine ◽  
Modulus Of Rupture ◽  
Mixed Effect ◽  
Ring Density ◽  
Commercial Thinning ◽  
Cambial Age ◽  
The Impact

This paper examined the impact of commercial thinning on selected wood properties of jack pine ( Pinus banksiana Lamb.). Wood properties evaluated include wood density (ring density, earlywood ring density, and latewood ring density), percentage of latewood in the ring, and wood bending properties. Nonlinear, mixed-effect models have been developed using data from three commercially thinned sites in eastern Canada. Ring density followed the same pattern as percentage of latewood, in which cambial age, relative height, and ring width were found to have important effects. Earlywood and latewood ring densities changed within the juvenile wood zone until a plateau was reached. Ring width affected earlywood and latewood ring densities mainly in narrow rings. Wood bending stiffness (measured by modulus of elasticity) and strength (measured by modulus of rupture) increased with cambial age and wood density; whereas, wood strength was also affected by ring width. Commercial thinning did not influence the developed models, but it had an indirect effect through increased ring width.

scholarly journals Effect of growth rate on the physical and mechanical properties of Douglas-fir in western Europe

2017 ◽  
Vol 47 (8) ◽  
pp. 1056-1065 ◽  
Author(s):  
C. Pollet ◽  
J.-M. Henin ◽  
J. Hébert ◽  
B. Jourez
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Management Practices ◽  
Juvenile Wood ◽  
Ring Width ◽  
Physical And Mechanical Properties ◽  
Douglas Fir ◽  
Mature Wood ◽  
Cambial Age ◽  
The Impact

To quantify the impact of forest management practices and tree growth rate on the potential uses of Douglas-fir wood, nine physico-mechanical properties were studied on more than 1250 standardized clear specimens. These were collected from trees cut in 11 even-aged stands (six trees per stand) located in Wallonia (southern Belgium). Stands were 40 to 69 years old, and mean tree girth was ca. 150 cm. Mean ring width of the 66 trees ranged from 3 to more than 7 mm. Statistical analysis showed significant but weak effects of ring width on the studied properties. Considered jointly, mean ring width and cambial age of the test specimens only explained 28% to 40% of the variability of their properties. Also, when ring width increases, these properties display higher decreases in juvenile wood than in mature wood. From a technological standpoint, maintaining mean ring width under 4 mm in juvenile wood and 6 mm in mature wood should accommodate all potential uses of Douglas-fir wood. However, considering that density appeared to be the main driver of wood properties, our results and the literature corroborate the importance of genetic selection as a complement to silvicultural measures to improve or guarantee the technological properties of Douglas-fir wood.

Pengaruh Tekanan dan Penggunaan Conplast terhadap Sifat Mekanik Eternit dari Abu Cangkang Sawit

2016 ◽  
Vol 8 (15) ◽  
pp. 47-54
Author(s):  
Haspiadi Haspiadi
Keyword(s):  
Mechanical Properties ◽  
Oil Palm ◽  
Modulus Of Elasticity ◽  
Modulus Of Rupture ◽  
Palm Shell ◽  
Oil Palm Shell ◽  
Density Values ◽  
Test Result

The purpose of this research is to know the influence of pressure and use of conplast against mechanical properties which are a Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) of plasterboard. The study is done because still low quality of plasterboard made from a mixture of ashes of oil-palm shell especially of the mechanical properties compared to the controls. The method of this reserach used variation of printed pressure and the addition of conplast. Test result is obtained that the highest value of Modulus of Elasticity (MOE) 90875.94 Kg/cm2, Modulus of Rupture (MOR) 61.16 Kg/cm2 and density values in generally good printed at the pressure 60 g/cm3 and the addition of conplast 25% as well as the composition of the ash of palm shell oil 40%: limestone 40%: cement 15%: fiber 5% and 300 mL of water. ABSTRAK Tujuan dari penelitian ini adalah untuk mengetahui pengaruh tekanan dan penggunaan conplast terhadap sifat mekanik yaitu kuat lentur dan keteguhan patah eternit berbahan dasar abu cangkang sawit. Penelitian ini dilakukan karena masi rendahnya mutu eternit berbahan campuran abu cangkang sawit dari bolier khususnya sifat mekanik dibandingkan dengan kontrol. Metode penelitian yang digunakan adalah dengan variasi tekanan cetak dan penambahan conplast. Hasil uji diperoleh bahwa kuat lentur tertinggi sebesar 90875,94 Kg/cm2 dan keteguhan patah sebesar 61,16 Kg/cm2, yang dicetak pada tekanan 60 g/cm3 dan penambahan conplast 25% dengan komposisi  abu cangkang sawit 40 %: kapur 40 % : semen 15 %: serat 5 % dan air 300 mL.Kata Kunci :  Abu cangkang sawit, conplast, kuat lentur, keteguhan patah.

scholarly journals The Difficulty of Predicting Eastern Spruce Dwarf Mistletoe in Lowland Black Spruce: Model Benchmarking in Northern Minnesota, USA

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 843
Author(s):  
Ella R. Gray ◽  
Matthew B. Russell ◽  
Marcella A. Windmuller-Campione
Keyword(s):  
Stand Structure ◽  
Black Spruce ◽  
Forest Health ◽  
Basal Area ◽  
Predictive Performance ◽  
Stand Age ◽  
Management Decisions ◽  
Dwarf Mistletoe ◽  
Growing Seasons ◽  
Model Interpretation

Insects, fungi, and diseases play an important role in forest stand development and subsequently, forest management decisions and treatments. As these disturbance agents commonly occur within and across landscapes, modeling has often been used to inform forest planning and management decisions. However, models are rarely benchmarked, leaving questions about their utility. Here, we assessed the predictive performance of a Bayesian hierarchical model through on–the-ground sampling to explore what features of stand structure or composition may be important factors related to eastern spruce dwarf mistletoe (Arceuthobium pusillum Peck) presence in lowland black spruce (Picea mariana (Mill.) B. S. P.). Twenty-five state-owned stands included in the predictive model were sampled during the 2019 and 2020 growing seasons. Within each stand, data related to the presence of eastern spruce dwarf mistletoe, stand structure, and species composition were collected. The model accurately predicted eastern spruce dwarf mistletoe occurrence for 13 of the 25 stands. The amount of living and dead black spruce basal area differed significantly based on model prediction and observed infestation, but trees per hectare, total living basal area, diameter at breast height, stand age, and species richness were not significantly different. Our results highlight the benefits of model benchmarking to improve model interpretation as well as to inform our understanding of forest health problems across diverse stand conditions.

Impact of Chemical Modification on the Physical and Mechanical Properties of Tropical Wood Material

2012 ◽  
Vol 576 ◽  
pp. 314-317
Author(s):  
Sinin Hamdan ◽  
M. Saiful Islam
Keyword(s):  
Mechanical Properties ◽  
Diazonium Salt ◽  
Treated Wood ◽  
Coupling Reaction ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Ft Ir ◽  
Ir Analysis ◽  
D Values ◽  
Benzene Diazonium

Five types of selected tropical light hardwoods were chemically modified with benzene diazonium salt to improve their physical and mechanical properties. Benzene diazonium salt underwent a coupling reaction with wood which was confirmed through FT-IR analysis. The compressive modulus of the treated wood increased, whereas modulus of rupture was shown to decrease on treatment. The modified wood samples had higher hardness (Shore D) values compared to that of the control ones.

scholarly journals Composites from Thermoplastic Natural Rubber Reinforced Rubberwood Sawdust: Effects of Sawdust Size and Content on Thermal, Physical, and Mechanical Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Chatree Homkhiew ◽  
Surasit Rawangwong ◽  
Worapong Boonchouytan ◽  
Wiriya Thongruang ◽  
Thanate Ratanawilai
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
High Density Polyethylene ◽  
High Performance ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Shore Hardness ◽  
Thermoplastic Natural Rubber ◽  
Plastic Content

The aim of this work is to investigate the effects of rubberwood sawdust (RWS) size and content as well as the ratio of natural rubber (NR)/high-density polyethylene (HDPE) blend on properties of RWS reinforced thermoplastic natural rubber (TPNR) composites. The addition of RWS about 30–50 wt% improved the modulus of the rupture and tensile strength of TPNR composites blending with NR/HDPE ratios of 60/40 and 50/50. TPNR composites reinforced with RWS 80 mesh yielded better tensile strength and modulus of rupture than the composites with RWS 40 mesh. The TPNR/RWS composites with larger HDPE content gave higher tensile, flexural, and Shore hardness properties and thermal stability as well as lower water absorption. The TPNR/RWS composites with larger plastic content were therefore suggested for applications requiring high performance of thermal, physical, and mechanical properties.

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