WOOD RESEARCH Volume 67, Number 5, 2022
Matheus Viana De Souza, Pedro Henrique Da Silva Cazella, Sérgio Augusto Mello Da Silva, Felipe Reis Rodrigues, Marjorie Perosso Herradon, Fabíola Medeiros Da Costa, Márcia Regina De Moura Aouada, Fauze Ahmad Aouada, Herisson Ferreira dos Santos, Edna Moura Pinto, Victor Almeida De Araujo, André Luis Christoforo, and Roberto Vasconcelos Pinheiro

Comparative study of particleboards with Hevea brasiliensis waste from different production and moisture configurations

After the production cycle of latex, Hevea brasiliensis trees become residual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density,short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived from rubberwood particles proved to be viable according to the technical standards.

WOOD RESEARCH Volume 66, Number 5, 2021
Francisco Antonio Rocco Lahr, Eduardo Chahud, Felipe Nascimento Arroyo, André Luis Christoforo, Edson Fernando Castanheira Rodrigues, João Paulo Boff Almeida, Vinicius Borges De Moura Aquino, and Herisson Ferreira dos Santos

Ratio analysis between compression and shearing of 72 Brazilian wood species

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 72 Brazilian species, separated from class C20 to C60. In the end, it was possible to conclude that the value displayed by the standard between the ratio of shear and compression in the direction parallel to the fibers is half of what actually happens in Brazilian species, showing an urgent review in the standard premises.

WOOD RESEARCH Volume 66, Number 4, 2021
Francisco Antonio Rocco Lahr, Vinicius Borges De Moura Aquino, Felipe Nascimento Arroyo, Herisson Ferreira dos Santos, Sergio Augusto Mello Silva, Anderson Renato Vobornik Wolenski, Carlos Maviael de Carvalho, João Paulo Boff Almeida, and André Luis Christoforo

Influence of stiffness related to the C40 strength class of the hardwood group established by the Brazilian standard in the design of timber structures

The Brazilian standard ABNT 7190 (1997) establishes the strength classes C20, C30, C40 and C60 for the proper framework of the different wood types in the group of hardwoods. Associated with the strength class, which is based on the compressive strength characteristic value parallel to the fibers (fc0,k), the standard stipulates the respective values representing the stiffness (Ec0), with 19500 MPa being the reference value for the class C40, essential variables in structural design. For being the C40 class is the one with the greatest amplitude (20 MPa), it is possible that the value 19500 MPa is not the best representation of stiffness. This work aimed to verify the representativeness the stiffness value established by the Brazilian standard for C40 wood. The result obtained from the average confidence interval indicates the value of 14110 MPa as being the most representative, which may imply structures that are supposedly more rigid than they really are.

WOOD RESEARCH Volume 64, Number 5, 2019
Tiago Capobianco Morando, André Luis Christoforo, Vinicius Borges De Moura Aquino, Francisco Antonio Rocco Lahr, Greyce Bernardes De Mello Rezende, and Raul Tadeu Lobato Ferreira

Characterization of the wood species Qualea albiflora for structural purposes

The present article aimed to characterize the wood specie Qualea albiflora (Mandioqueira), in order to enable its use for structural purposes. The tests to obtain the physical and mechanical characteristics were carried out according to the Brazilian standard ABNT NBR 7190, allowing the classification of the Qualea albiflora in the strength class C60, a wood species suitable for use in heavy constructions. After the characterization, it was verified with the aid of regression models (linear, logarithmic, exponential and geometric), that it is not possible to make use of the apparent density in the estimation of the other physical and mechanical characteristics, obtaining a bad adjustment in all the cases (R² < 50.00%) and the non-representativeness of the models adopted (P-Value> 0.05).

WOOD RESEARCH Volume 65, Number 5, 2020
Ana Laura Soler Cunha Buzo, Sergio Augusto Mello Silva, Vinicius Borges De Moura Aquino, Eduardo Chahud, Luiz Antonio Melgaço Nunes Branco, Diego Henrique De Almeida, André Luis Christoforo, João Paulo Boff Almeida, and Francisco Antonio Rocco Lahr

Addition of sugarcane bagasse for the production of particleboards bonded with urea-formaldehyde and polyurethane resins

The present study deals with a production of pine particleboards using the sugarcane bagasse content and using castor-oil based bicomponent polyurethane resin and urea-formaldehyde resin. The influence of incorporation of sugarcane bagasse on the physical and mechanical properties of the composites was evaluated. The particleboards were produced according Brazilian standard ABNT NBR 14810, but performance requirements have been analyzed using Brazilian and international standards, as well. Treatment 2, using PU resin, were considered the best treatment using pine residue and sugarcane bagasse, presenting physical properties values 60% lower and mechanical properties 65% higher on average when compared with panel without sugarcane bagasse, indicating the good performance of sugarcane incorporation and the possibility of its use on commercial purpose for thermal and acoustic insulation. The addition of sugarcane bagasse improved physical and mechanical properties of particleboards when compared to panels manufactured from pine wood particles only. Statistical analysis indicated that moisture content and bagasse content were significant, enhancing properties when compared with reference treatments.

WOOD RESEARCH Volume 65, Number 1, 2020
Anderson Renato Vobornik Wolenski, Rodrigo Guerra Peixoto, Veronika Fedotova, André Luis Christoforo, and Francisco Antonio Rocco Lahr

Short note: Shear strength estimation model for tropical wood species

For safety reasons, wood strength values are calculated based on their characteristic values. Brazilian national standard (NBR, in Portuguese “Norma Brasileira Regulamentadora”) 7190 (1997) establishes ratios for characteristic strength estimation and three forms of wood characterization, with an emphasis on the simplified procedure for common species, which allows obtaining the strength characteristic values through equations correlating different mechanical properties. The present work evaluates the accuracy of the relation proposed by NBR 7190 (1997) of shear strength along the grain (fv0,k) to compression strength along the grain (fc0,k) (fv0,k=0.12 fc0,k). 960 experimental measurements of shear and compression strength values were performed for 40 hardwood species, and the precision of the relation proposed by the Brazilian standard was evaluated using the analysis of variance (ANOVA) method. Linear, exponential, logarithmic, and geometric regression models were used as an alternative to the NBR relation for shear strength estimation. The statistical analysis revealed that the geometric regression is the model of best fit.

WOOD RESEARCH Volume 66, Number 2, 2021
Vinicius Borges De Moura Aquino, Marcus Vinicius Pereira De Freitas, Claudia Queiroz De Vasconcelos, João Paulo Boff Almeida, Felipe Nascimento Arroyo, Edson Fernando Castanheira Rodrigues, André Luis Christoforo, Diego Henrique De Almeida, Sergio Augusto Mello Silva, Diogo Aparecido Lopes Silva, Roberto Vasconcelos Pinheiro, and Francisco Antonio Rocco Lahr

Physical and mechanical characterization of Planchonella Pachycarpa wood species for use in structural purpose

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.