scholarly journals RATIO ANALYSIS BETWEEN COMPRESSION AND SHEARING OF 72 BRAZILIAN WOOD SPECIES

Wood Research ◽  
2021 ◽  
Vol 66 (5) ◽  
pp. 711-720
Author(s):  
FRANCISCO ANTONIO ROCCO LAHR ◽  
EDUARDO CHAHUD ◽  
FELIPE NASCIMENTO ARROYO ◽  
ANDRÉ LUIS CHRISTOFORO ◽  
EDSON FERNANDO CASTANHEIRA RODRIGUES ◽  
...  
Keyword(s):  
Wood Species ◽  
Ratio Analysis ◽  
Wood Structure ◽  
Brazilian Species ◽  
Simplified Method ◽  
Brazilian Standard

The Brazilian standard ABNT NBR 7190 (1997) governs the premises for the wood structure sizing through a table and the simplified method. Thus, this research aims to analyze whether the simplified method shown in the standard matches the resistance values of 72Brazilian species, separated from class C20 to C60. In the end, it was possible to conclude that the value displayed by the standard between theratio of shear and compressionin thedirection parallel to the fibers is half of what actually happens in Brazilian species, showing anurgent review in the standard premises.

Influence of Moisture Content in some Mechanical Properties of Two Brazilian Tropical Wood Species

2014 ◽  
Vol 1025-1026 ◽  
pp. 42-45 ◽  
Author(s):  
Luiz A. Melgaço N. Branco ◽  
Eduardo Chahud ◽  
André Luis Christoforo ◽  
Francisco Antonio Rocco Lahr ◽  
Rosane A.G. Battistelle ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Moisture Content ◽  
Analysis Of Variance ◽  
Wood Species ◽  
Modulus Of Elasticity ◽  
Modulus Of Rupture ◽  
Tropical Wood ◽  
Fiber Saturation ◽  
Brazilian Standard

This study aimed, with the aid of analysis of variance (ANOVA), to investigate and quantify the influence of moisture ranging between 12% and over 30% (fiber saturation) on the mechanical properties: strength and modulus of elasticity in compression and in tension parallel to grain; modulus of rupture and modulus of elasticity in static bending; shear strength parallel to grain considering wood species Ipê (Tabebuia sp) and Angelim Araroba (Vataireopsis araroba). Tests were performed according to the assumptions and calculating methods Brazilian standard ABNT NBR 7190, Anexx B, totalizing 400 tests. Results of ANOVA revealed a significant reduction (16% on average) for mechanical properties wood due to the increase in moisture content from 12% to over 30% (fiber saturation). The same behavior also occurred when assembly containing the two species was considered.

Evaluation of Longitudinal Modulus of Elasticity in Wood Species for Structural Application

2014 ◽  
Vol 1025-1026 ◽  
pp. 192-195
Author(s):  
Eduardo Chahud ◽  
Luiz Antônio Melgaço Nunes Branco ◽  
André Luis Christoforo ◽  
Francisco Antonio Rocco Lahr ◽  
Rosane Aparecida Gomes Battistelle ◽  
...  
Keyword(s):  
Wood Species ◽  
Modulus Of Elasticity ◽  
Mechanical Test ◽  
Font Size ◽  
Bending Tests ◽  
Structural Application ◽  
Longitudinal Elastic Modulus ◽  
Longitudinal Modulus ◽  
Dipteryx Odorata ◽  
Brazilian Standard

1024x768 This research aimed to investigate possible differences in values of longitudinal modulus of elasticity for wood species usually employed for structural purposes, as Castanheira (Bertholletia excelsa), Cambará (Erisma uncinatum), Cumaru (Dipteryx odorata), Jatobá (Hymenaea stilbocarpa), Garapa (Apuleia leiocarpa) and Peroba Rosa (Aspidosperma polyneuron), obtained from compression and tension parallel to grain, and static bending tests. Recommendations of the Brazilian standard ABNT NBR 7190:1997, Annex B, were followed. Statistical analysis results for the cited properties, had equivalent averages for the six wood species analyzed. This confirms that any of the three tests can be used to obtain the longitudinal elastic modulus and which could avoid the necessity of evaluating stiffness values for wood by more than one kind of mechanical test. Normal 0 21 false false false PT-BR X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

scholarly journals PHYSICAL AND MECHANICAL CHARACTERIZATION OF PLANCHONELLA PACHYCARPA WOOD SPECIES FOR USE IN STRUCTURAL PURPOSE

Wood Research ◽  
2021 ◽  
Vol 66 (2) ◽  
pp. 267-276
Author(s):  
Vinicius Borges De Moura Aquino ◽  
Marcus Vinicius Pereira De Freitas ◽  
Claudia Queiroz De Vasconcelos ◽  
João Paulo Boff Almeida ◽  
Felipe Nascimento Arroyo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Apparent Density ◽  
Wood Species ◽  
Regression Models ◽  
Physical And Mechanical Properties ◽  
Stiffness Properties ◽  
Longitudinal Elastic Modulus ◽  
Structural Purpose ◽  
Brazilian Standard

This research aimed to characterize the wood species Goiabão (Planchonella pachycarpa), following the precepts set forth in the Brazilian standard ABNT NBR 7190, as well as to evaluate the possibility of estimating physical and mechanical properties, using the analysis of variance (ANOVA) as a function of apparent density, and also to estimate the stiffness properties as a function of the respective strength property. The physical and mechanical properties were considered adequate for the use of this wood for structural purposes, being classified in class C40. According to the results of the regression models, it is possible to estimate the tensile strength parallel to the fibers as a function of the apparent density. It was also possible to estimate the longitudinal elastic modulus in the compression parallel to the fibers as a function of the compressive strength parallel to the fibers.

scholarly journals Influence of the apparent density on the shrinkage of 43 tropical wood species

2019 ◽  
Vol 41 (1) ◽  
pp. 30947
Author(s):  
Fabrício Moura Dias ◽  
Tiago Hendrigo de Almeida ◽  
Victor Almeida De Araújo ◽  
Tulio Hallak Panzera ◽  
André Luis Christoforo ◽  
...  
Keyword(s):  
Natural Resources ◽  
Apparent Density ◽  
Wood Species ◽  
Timber Species ◽  
Test Results ◽  
Araucaria Angustifolia ◽  
Tropical Wood ◽  
Brazilian Standard

Recently, more wood species are gaining space in market. Hence, it is important to enlarge the utilization of non-traditional woods, which shall be able to replace the most popular species, provided that similar performances are respected. In contrast, the sustainable exploitations of natural resources by timber producers demand alternatives to exchange the use of restricted or blocked tropical wood species (e.g. Araucaria angustifolia) by other timbers, which are liable for commercial certification. This research, based on the test results obtained according to the Brazilian Standard prescriptions (NBR-7190 - Annex B), aimed at evaluating the influence of the apparent density on radial and tangential shrinkages, considering the results for forty-three Brazilian tropical wood species. Usually, this parameter is regarded as necessary to define the timber species to different applications. The results showed low dependence among those variables, considering the information from the literature.

scholarly journals Investigation of the fiber saturation point of tropical Brazilian wood species

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 5379-5387
Author(s):  
Tiago H. Almeida ◽  
Diego H. Almeida ◽  
Vinicius B. M. Aquino ◽  
Eduardo Chahud ◽  
Roberto V. Pinheiro ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wood Species ◽  
Wood Specimen ◽  
Basic Density ◽  
Fiber Saturation Point ◽  
Coefficient Of Determination ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Standard Code ◽  
Brazilian Standard

The fiber saturation point (FSP) is an important parameter of wood material, related to dimensional stability and variations of mechanical performance. This paper investigated the FSP values of 15 tropical Brazilian wood species covering all strength classes of the Brazilian standard code. An additional goal was to estimate FSP value based on the wood’s apparent density. The FSP values were determined by measuring the wood specimen dimensions during moisture content reduction from the saturated state. Wood densities at 0% and 12% moisture contents and basic density were determined according to the Brazilian standard code. The average FSP for all wood species was 21.6% moisture content. Among density values, good correlations were observed, and a multivariate regression model for FSP estimation based on wood densities presented a coefficient of determination equal to 13.07%. There was no correlation between FSP and wood densities, suggesting that this parameter is almost constant regardless of the wood species.

scholarly journals A estrutura do xilema secundário de Mimosa daleoides Benth. (Leguminosae Mimosoideae)

1982 ◽  
Vol 4 (4) ◽  
pp. 107 ◽  
Author(s):  
José Newton Cardoso Marchiori
Keyword(s):  
Wood Species ◽  
Secondary Xylem ◽  
Wood Structure

The gross, macroscopic and microscopic wood structure of Mimosa daleoides Benth. (Leguminosae Mimosoideae) are described.Aside from quantitative and histometric data from the secondary xylem, illustrations of wood are furnished.The secondary xylem of this shrub is compared with other wood species of the same genus.

A simplified method of emulsion coating and development for quantitative electron microscopic radioautography

1978 ◽  
Vol 36 (2) ◽  
pp. 64-65
Author(s):  
K. Yoshida ◽  
F. Murata ◽  
S. Ohno ◽  
T. Nagata
Keyword(s):  
Mass Production ◽  
Identical Condition ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Simplified Method ◽  
Complicated Process ◽  
Critical Problems ◽  
Electron Microscopic Radioautography ◽  
Quantitative Radioautography

IntroductionSeveral methods of mounting emulsion for radioautography at the electron microscopic level have been reported. From the viewpoint of quantitative radioautography, however, there are many critical problems in the procedure to produce radioautographs. For example, it is necessary to apply and develop emulsions in several experimental groups under an identical condition. Moreover, it is necessary to treat a lot of grids at the same time in the dark room for statistical analysis. Since the complicated process and technical difficulties in these procedures are inadequate to conduct a quantitative analysis of many radioautographs at once, many factors may bring about unexpected results. In order to improve these complicated procedures, a simplified dropping method for mass production of radioautographs under an identical condition was previously reported. However, this procedure was not completely satisfactory from the viewpoint of emulsion homogeneity. This paper reports another improved procedure employing wire loops.

Rate of Sublimation of Ice by Radiative Heating in Freeze-Etching

1980 ◽  
Vol 38 ◽  
pp. 618-619
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Heat Flux ◽  
Freeze Fracture ◽  
Constant Heat Flux ◽  
Radiative Heating ◽  
Constant Heat ◽  
Entire Sample ◽  
Simplified Method ◽  
Freeze Etching ◽  
Sublimation Rates ◽  
Fractured Surface

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.

516: A Simplified Method to Estimate the Absolute Renal Uptake of 99MTC-DMSA: Evaluation with a New Model using the Radioactivity of Nephrectomy Specimens as Reference

2005 ◽  
Vol 173 (4S) ◽  
pp. 140-141
Author(s):  
Mariana Lima ◽  
Celso D. Ramos ◽  
Sérgio Q. Brunetto ◽  
Marcelo Lopes de Lima ◽  
Carla R.M. Sansana ◽  
...  
Keyword(s):  
New Model ◽  
Renal Uptake ◽  
Simplified Method ◽  
The Absolute

Moment ratio analysis of multiple breath nitrogen washout in infants with lung disease

2000 ◽  
Vol 15 (6) ◽  
pp. 1094 ◽  
Author(s):  
A. Schibler ◽  
M. Schneider ◽  
U. Frey ◽  
R. Kraemer
Keyword(s):  
Lung Disease ◽  
Ratio Analysis ◽  
Nitrogen Washout ◽  
Moment Ratio
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