Tenacidade da madeira como função da densidade aparente

Almeida, Diego Henrique de; Scaliante, Ricardo de Mello; Christofóro, André Luis; Varanda, Luciano Donizeti; Lahr, Francisco Antônio Rocco; Dias, Antônio Alves; Calil, Carlito

doi:10.1590/s0100-67622014000100020

Cited by 34 publications

(51 citation statements)

References 8 publications

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“…Almeida et al [17], using linear, polynomial, quadratic and cubic regression models, evaluated the possibility of estimate toughness based on density for six wood species.…”

Section: Introductionmentioning

confidence: 99%

Density as Estimator of Shrinkage for Some Brazilian Wood Species

Cavalheiro¹,

Almeida²,

Almeida³

et al. 2016

ijme

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Shrinkage and coefficient of anisotropy are fundamental physical parameters in analysis of dimensional stability of timber structures members. In Brazil, properties of wood are obtained according to assumptions and calculation required by Annex B of ABNT NBR 7190: 1997 (Timber Structures Design). Among the physical properties, density appears as the easiest one to be experimentally obtained, defined by ratio between mass of the sample and its volume. To evaluate the possibility of estimating shrinkage (longitudinal, RL; radial, RR; tangential, RT; volumetric, RV; and coefficient of anisotropy, CA) of wood depending on density, this study aimed to test regression models (linear, exponential, logarithmic, geometric) using basic density (ρ bas ) and apparent density (ρ 12 ) as independent variables. For this purpose, five wood species belonging to conifers: Pinus sp., Pinus oocarpa; and dicotyledonous: Paricá (Schizolobium amazonicum), Jatobá (Hymenaea sp.) and Lyptus®, were employed. In all, 23 samples for Pinus sp.; 15 for Pinus oocarpa; 28 for Paricá; 16 for Lyptus®; and 11 for Jatobá were produced, totaling 651 determinations. Results of analysis of variance for regression models indicated insignificance of the adjustments obtained by adopting densities as estimators of shrinkage and coefficient of anisotropy for this set of wood species. Only models involving basic density and apparent density were significant, wherein the optimal settings were from linear case, exhibiting coefficient of determination (R 2 ) 91.72% (for softwoods) and 83.36% (for hardwoods).

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“…Almeida et al [17], using linear, polynomial, quadratic and cubic regression models, evaluated the possibility of estimate toughness based on density for six wood species.…”

Section: Introductionmentioning

confidence: 99%

Density as Estimator of Shrinkage for Some Brazilian Wood Species

Cavalheiro¹,

Almeida²,

Almeida³

et al. 2016

ijme

View full text Add to dashboard Cite

show abstract

“…From the adjustments considered significant in Table 4, only the strength in compression perpendicular to grain and the flexural modulus of elasticity are effectively considered as good adjustments, since they have coefficients of determination higher than 70%. It should be noted that Almeida et al (2014) found good regression models (R 2 > 70%) in the estimation of hardness of the hardwoods group as a function of apparent density, and these results were justified by the use of species of different densities.…”

Section: Resultsmentioning

confidence: 74%

“…It is denser than medium apparent density woods, such as Liquidambar sp. (Freitas et al, 2015), Pinus and Teca (Almeida et al, 2014), Cedrela fissilis, Clonal hybrids and Hovenia dulcis (Motta et al, 2014), ranging from 0.478 to 0.577 g/cm³. Light wood, such as Toona ciliata (Braz et al, 2013), Paricá (Almeida et al, 2013) and Gallesia integrifólia (Motta et al, 2014) have a density varying between 0.318 g/cm³ and 0.370 g/cm³.…”

Section: Resultsmentioning

confidence: 99%

“…The use of wood for a wide range of purposes depends on the knowledge of its properties (physical, chemical, mechanical and anatomical) for a more rational use of this material, which comes from natural sources, perfectly meets the requirements imposed by the current environmental appeal of products and services provided by man (Almeida et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Since the density is a basic physical property, its values allows determining an adequate estimate of some wood properties (Almeida et al, 2014;Silveira et al, 2013). The estimation of strength and stiffness properties by density via mathematical models (regression models) allows the engineer, known the density of the wood species chosen and determined experimentally, to estimate the values of strength and stiffness to be used in the pre-designing of the structure.…”

Section: Introductionmentioning

confidence: 99%

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Full Characterization of Calycophyllum Multiflorum Wood Specie

et al. 2017

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Wood is a material that for years has been used by man for a variety of purposes, particularly in rural and civil constructions and furniture industry. The possibility of shortages of some wood species, the characterization of other unfamiliar species is an alternative source for use in civil and rural construction. This study aimed to determine, with the aid of Brazilian standard NBR 7190, physical and mechanical properties of Castelo (Calycophyllum multiflorum) wood specie. Twelve determinations were obtained by property, totaling 204 experimental values. In the characterization of wood, regression models were used to estimate the values of timber strength and stiffness as a function of apparent density, being density the physical property more simple to be obtained. The results of mechanical properties showed consistent with the performance of other species used in construction, which highlights the potential use of the Castelo wood in structural design. Regression models, apparent density was considered significant in the estimation of only 4 among the 14 properties for wood strength and stiffness.

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Polylactic acid/Lignocellulosic residue composites compatibilized through a starch coating

et al. 2020

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The use of natural fiber residues as reinforcement in biodegradable composites has been performed; however, the incompatible interface limits the applications. In this work, the use of starch coating as a natural coupling agent was studied in three different natural residues: sugarcane bagasse, maçaranduba, and pinus wastes, aiming biodegradable composites. The coating in bagasse showed low efficiency, with low thickness and failures, due to residue intrinsic higher surface area; while the wood residues showed shorter fibers with uniform starch deposition. These results affected the compatibility between filler and matrix; while the bagasse composite showed voids and decrease in the mechanical properties; however, the maçaranduba and pinus showed an increase in the stiffness and strength. All the coated fiber composites showed stable thermal properties and an increase in the crystallinity in the coated samples. The addition of the natural filler resulted in a high water absorption with coated samples absorbing six times more water than neat PLA and without stabilization in a short time. This characteristic may favor the initial abiotic hydrolysis in the biodegradation, showing that the material could be an option to produce short‐life packaging in dry environments.

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Tenacidade da madeira como função da densidade aparente

Cited by 34 publications

References 8 publications

Density as Estimator of Shrinkage for Some Brazilian Wood Species

Density as Estimator of Shrinkage for Some Brazilian Wood Species

Full Characterization of Calycophyllum Multiflorum Wood Specie

Polylactic acid/Lignocellulosic residue composites compatibilized through a starch coating

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