Search

Made available in DSpace on 2020-12-12T02:13:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 This paper is based on an evaluation of the industrialization levels and main production systems of Brazilian timber housing producers. Two methods were used to investigate this understudied topic. Literature-based projection was carried out to identify the production system of each sampled company, from the construction technique(s) produced by the same. The second method consisted of face-to-face interviews to identify the current production system of each producer. For both methodologies, the timber housing sector presented a considerable level of industrial development in view of the greater popularity of prefabrication systems. Due to admissions to enable the system identification from the literature-based projections, a result contrast in artisanal production was verified between both methodologies. Despite the sampling difference, the two methods showed typical results for the industrial processes. Thus, few artisanal developers and the visible amount of industrial-based producers could regard this sector as industrial-featured. Research Group on Development of Lignocellulosic Products (LIGNO) São Paulo State University (UNESP), Campus of Itapeva, 519, Geraldo Alckmin Department of Timber Industrial Engineering São Paulo State University (UNESP), Campus of Itapeva, 519 Geraldo Alckmin Department of Forest Science University of São Paulo (USP) Luiz de Queiroz College of Agriculture, 11, Pádua Dias Avenue Research Group on Development of Lignocellulosic Products (LIGNO) São Paulo State University (UNESP), Campus of Itapeva, 519, Geraldo Alckmin Department of Timber Industrial Engineering São Paulo State University (UNESP), Campus of Itapeva, 519 Geraldo Alckmin

Reforestation wood is interesting for construction, due to its potential as material source for manufacturing. For this purpose, the Eucalyptus genus has resulted in a better characterization of the material properties. During the production process, wood is machined at some stage, which influences the wood gluing quality. This study considered the performance of Eucalyptus saligna wood joints bonded with four commercial polyvinyl-acetate-based resins with different physical characteristics and chemical compositions. The surfaces of samples were prepared and machined by an up-milling process, using a planer, with wood feed rates of 6 m/min, 11 m/min, 16 m/min, and 21 m/min, which had advances per tooth of 0.25 mm, 0.45 mm, 0.66 mm, and 0.87 mm, respectively. The samples were prepared for shear strength testing of the glue line. During the preparation, all pieces were randomly bonded with regards to the formation plans of wood growth rings. Shear strength values were statistically compared to analysis of variance and Tukey test. Only C4 adhesive reached good results at all feed rates as well as having the best shear strength compared to other resins. Commercial adhesives had distinct interactions on the adhesive-wood interface, which resulted in different adhesion strengths.

Made available in DSpace on 2020-12-12T01:31:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-05-01 A high-density particleboard composed of peanut shells (Arachis hypogaea L.), an agro-industrial residue, and bamboo wastes of the species Dendrocalamus giganteus (branches and apical part), bonded with a two-component polyurethane resin based on castor oil (Ricinus communis L.) in the proportion of 12% of the particleboard mass, was produced. Four types of specimens were prepared according to the percentage of peanut shells: 0%, 10%, 20%, and 30%. Mechanical characteristics were evaluated through the flexural strength tests for modulus of rupture, modulus of elasticity, perpendicular traction, and screw pull resistance. The particleboard reached an average density of 917.2 kg/m3, meaning that it could be classified as high-density particleboard. The results of the mechanical tests indicated that the specimens containing a mixture in the proportion of 90% bamboo and 10% peanut hull presented the best mechanical strength. The experiment produced particleboards with a satisfactory mechanical physical performance that met the standards ABNT NBR 14.810-2 and ANSI A208-1, supporting the use of the peanut shell residue in the manufacture of particleboards to be used in internal environments and allowing the applicability of this residue through additional value. Mechanical Engineering Department UNESP Unesp Univ Estadual Paulista, Avenida Luiz Edmundo Carrijo Coube Wood Industrial Engineering Department UNESP Univ Estadual Paulista, Rua Geraldo Alckmin Federal Institute of Paraná, Avenida Dr. Tito Mechanical Engineering Department UNESP Unesp Univ Estadual Paulista, Avenida Luiz Edmundo Carrijo Coube Wood Industrial Engineering Department UNESP Univ Estadual Paulista, Rua Geraldo Alckmin

RESUMO Este trabalho teve como objetivo analisar o desempenho de juntas coladas de madeiras da espécie Pinus elliottii com a utilização de dois adesivos comerciais à base de poliacetato de vinila (PVAc), com diferentes características físicas e composição química, ambos testados nas formas diluída em água e não diluída. As superfícies dos corpos de prova de madeira foram usinadas em processo de fresamento discordante. Uma plaina desengrossadeira de madeira com cabeçote de quatro facas afiadas de aço carbono semi-rápido à base de Cr-Ni-V foi utilizada. Essa máquina foi preparada para atuar com velocidade de corte (Vc) de 30,18 m.s-1 e velocidade de avanço da madeira (Vf) de 11,75 m.min-1, resultando num avanço por dente (fz) de 0,56 mm. Os corpos de prova foram confeccionados para ensaios de resistência a ruptura na linha de cola por esforços solicitantes ao cisalhamento de acordo com a ABNT NBR 7190:1997. Para a confecção dos corpos de prova, as peças foram coladas de maneira aleatória em relação aos planos de formação dos anéis de crescimento da madeira. Os seguintes valores médios de resistência ao cisalhamento na linha de cola (fv0), na forma diluída e não diluída foram, respectivamente, PVAc-M: 6,52 e 6,49 MPa; PVAc-H: 5,86 e 5,15 MPa. Em relação à resistência ao cisalhamento na linha de cola, concluiu-se que ambos adesivos na forma diluída com 33,33 % de água resultaram em maior adesão em relação à formulação original, sendo que o adesivo diluído do tipo M proporcionou um aumento de 21,01% na resistência à ruptura em relação ao adesivo não diluido do tipo “H”. ABSTRACT This study aimed to analyze the performance of bonded joints of the Pinus elliottii wood species with the use of two commercial adhesives based on vinyl polyacetate (PVAc) with different physical characteristics and chemical composition, both tested on water diluted and undiluted modes. The surfaces of wood specimens were machined in discordant milling process. A wood thickness planer with headstock of four semi-fast carbon steel sharpened knives based on Cr-Ni-V was used. This machine was prepared to operate with cutting speed (Vc) of 30.18 ms-1 and feed rate of wood (Vf) of 11.75 m.min-1, resulting in an feed rate per tooth (fz) of 0.56 mm. The specimens were prepared for tests of resistance to rupture in the glue line by the shear stress efforts according to the ABNT NBR 7190:1997 standard. In order to specimen preparation, the parts were randomly glued in relation to the formation plans of the wood growth rings. The following average values of shear strength in the glue line (fv0) obtained in diluted and undiluted forms were, respectively, PVAc -M: 6.52 and 6.49 MPa; PVAc -H: 5.86 and 5.15 MPa. In relation to the shear stress at the glue line, it was concluded that both adhesives in diluted form with 33.33% of water resulted in higher adhesion strength in comparison to the original formulation, whereas the diluted adhesive type M provided an increasing of 21.01% regarding the undiluted adhesive of type H.

In the current competitive market, production efficiency and product quality are prioritized by the whole industry. Machinery characterization is an understudied topic, particularly in those sectors focused on basic raw material production, processing, and/or heavy industrialization. For this reason, the wooden housing sector requires evaluation to identify its mechanical potential and support future policies dealing with industrial development. This study aimed to identify the equipment and machinery from Brazilian timber housing producers. Such a sectoral study involved individual personal data collection by way of face-to-face interviews. Sampled producers were asked about equipment/machinery size, drying process availability, and the range of overall obsolescence from these devices. Thus, tools, portable machines, and medium-sized machinery exhibited the highest popularities, revealing a lower industrial level. Most of these producers do not have machined drying processes because of the demand for static infrastructures. The low obsolescence was a result of the greater utilization of compact equipment, which is easier to replace because of its low cost. Lower-cost machinery could also stimulate in the creation of new businesses for this sector.

Wood is a natural material with great variability in its mechanical properties. This study analyzed the effectiveness of the impulse excitation technique (IET) to characterize the stiffness of 10-year-old Eucalyptus grandis wood at three different heights of 3 m, 6 m, and 9 m from the bottom (height A, B, and C, respectively). A nondestructive testing method—excitation impulse, using Sonelastic® PC-based technology—and a destructive static bending test were used. The mean value for the modulus of elasticity (MOE) in bending was 16.4 GPa and in IET the value was 16.6 GPa. The average values for MOE in static bending were 14.8 GPa at height A, 17.9 GPa at height B, and 17.0 GPa at height C, demonstrating that the greater the height in the trunk of the tree the greater its modulus of elasticity. The correlation equation between static MOE and dynamic MOE was MOESTAT = 0.743.MOEDYN + 4.0983, with the coefficient of determination of R² = 0.85.