Academic literature on the topic 'Plywood – Mechanical properties'

The second part of the paper summarizes results of an institutional research aimed at the determination of physical and mechanical properties of different sets of plywood sheets pressed under different conditions. The first part dealt with the determination of compressibility or values of decreasing the thickness of pressed plywood sheets. In this second part, results are summarized of the analysis of physical and mechanical properties of the set of whole-beech plywood sheets of the nominal thickness of veneers amounting to 1.5 mm. The plywood sheets were manufactured as seven-ply and urea-formaldehyde resin DUKOL S was used for their production. The sheets were pressed using a pressure of 1.5 and 1.7 MPa. Following parameters were analyzed: moisture, density, bending strength, MOE in bending and shear strength.

This paper gives the results of ghora neem (Melia azedarach) plywood for assessing it as an alternative raw material for plywood industries. Five ply ghora neem plywood of 2400 mm×1200 mm×12 mm size was manufactured using urea formaldehyde adhesive. The important physical and mechanical properties were examined for assessing its quality. The results of physical and mechanical properties of ghora neem plywood were compared with the data obtained with existing market available plywood manufactured with shimul (Bombax ceiba). The density of ghora neem plywood and shimul plywood was 541.00 and 499.80 kg/m3 respectively. The MOR was 58.33 N/mm2 for ghora neem plywood while it was 32.52 N/mm2 for the shimul plywood. The MOE was found for ghora neem plywood 3950.01 N/mm2 and on the other hand, the shimul plywood showed 3224.15 N/mm2. The ghora neem plywood showed better performance for both physical and mechanical properties and it also follows the standard. DOI: http://dx.doi.org/10.3329/bjsir.v49i1.18855 Bangladesh J. Sci. Ind. Res. 49(1), 47-52, 2014

Bambusa distegia were used to make bamboo thread plywood by the process of producing thread, dipping thread into glue, assembling pattern and pressing. Influence of hot pressing pressure on mechanical properties of bambusa distegia thread plywood was investigated, which was 2.0MPa，2.5MPa，3.0MPa，3.5MPa and 4.0MPa respectively. The results indicate that the modulus of rupture(MOR), modulus of elasticity(MOE), compressive strength(CS), and horizontal shear strength(HSS) increase with the increasing of hot pressing pressure. Mechanical properties of the Bambusa distegia thread plywood are higher than the indices of plywood for concrete form and the indices of plywood for container flooring.

Impact of phenol film grammage on chosen mechanical properties of plywood. For the purpose of this research several plywood samples with a thickness of 15 mm were produced and coated, in industrial conditions, with 5 different variants of phenol films varying in terms of grammage (40/120 g/m2, 60/145 g/m2, 60/167 g/m2, 80/220 g/m2, 2 × 80/220 g/m2). Finished plywood was tested for abrasion resistance, MOR, MOE and density. It was concluded that higher grammage of phenol film increases wear resistance and final density of plywood. Plywood coated with two-layer phenol film with grammage of 80/220 g/m2 had 4 times higher rate of abrasion resistance in comparison with plywood coated with phenol film with surface density of 40/120 g/m2. Coating plywood surface with phenol films generally decreases MOR values, in comparison with uncoated plywood. In terms of MOE, there were no evidence of conclusive relation, despite statistically significant differences between each variant.

Impact of phenol film grammage on chosen mechanical properties of plywood. For the purpose of this research several plywood samples with a thickness of 15 mm were produced and coated, in industrial conditions, with 5 different variants of phenol films varying in terms of grammage (40/120 g/m2, 60/145 g/m2, 60/167 g/m2, 80/220 g/m2, 2 × 80/220 g/m2). Finished plywood was tested for abrasion resistance, MOR, MOE and density. It was concluded that higher grammage of phenol film increases wear resistance and final density of plywood. Plywood coated with two-layer phenol film with grammage of 80/220 g/m2 had 4 times higher rate of abrasion resistance in comparison with plywood coated with phenol film with surface density of 40/120 g/m2. Coating plywood surface with phenol films generally decreases MOR values, in comparison with uncoated plywood. In terms of MOE, there were no evidence of conclusive relation, despite statistically significant differences between each variant.

The paper summarizes the results of institutional research aimed at new types of combined plywood materials. Under pilot plant conditions, three variants of combined plywood materials were pressed, namely with the layer of fibreglass, with a core cork layer and with a cork wear layer on one side of the plywood surface and a cork core. Tests of selected physical and mechanical properties were carried out on these materials including the basic statistical evaluation. Comparisons with plywood materials Multiplex 15 and 20 mm in thickness were also made.

The tensile mechanical properties of bamboo mat and curtain plywood（for short bamboo plywood）were studied through “electrometric method”. It was proved that in the range of elastic deformation，the Poisson′s ratio and the elastic modulus of the bamboo plywood were not constant. The Poisson′s ratio of the bamboo plywood decreased nonlinearly with the load increase that Poisson′s ratio decreased markedly when the load was less than 1kN，and decreased gently when more than 1kN.The tensile elastic modulus of the bamboo plywood also increased nonlinearly with the load increase that the tensile modulus of elasticity increased drastically when the load was less than 800N，and increased less when exceeded 800N. In the process of loading，the tensile deformation、the tensile stress and strain all increased linearly with the load increase，and the tensile stress and strain both were linearly relevant to tensile deformation.

The objective of this study was to determine the physical and mechanical properties of plywood made of punak (Tetramerista glabra Miq.), meranti bunga (Shorea teysmanniana Dyer ex Brandis), mempisang (Alphonsea spp.), suntai (Palaqium burckii H.J.L.), and pasak linggo (Aglaia argentea Blume). Liquid urea formaldehyde (UF) was used as an adhesive. Data analysis was carried out using a completely randomized design. Results showed that the moisture content and density of plywood produced in this study were around 10.4-10.95% and 0.65 to 0.93 g/cm3, respectively. The modulus of elasticity (MOE) and modulus of rupture (MOR) of plywood produced were between 63.371-123.548 kg/cm2 and 517-1.052 kg/cm2, respectively. It was also found that the tensile strength and bonding strength of the plywood produced were 461.6-1.095 kg/cm2 and 18.97-31.79 kg/cm2, respectively. It was recorded that moisture content and the bonding strength of the plywood produced met the Indonesian National Standard of Plywood. Among others, plywood produced from pasak linggo showed a superior quality. Referring to statistical analysis, it was confirmed that physical and mechanical properties of plywood were significantly affected by wood species, except moisture content. Keywords: mechanical properties, physical properties, plywood, Riau wood species

In this study, a wood-based X-type lattice sandwich structure was fabricated by an insertion glue method using medium density fiberboard (MDF) and plywood as panels. Birch was used for the core. The mechanical properties and failure modes of the wood-based X-type lattice sandwich structure were investigated by an out-of-plane compressive test, a short beam shear test, and their matching analytical models. The out-of-plane compressive test and the compression analytical model showed that the failure mode of the plywood and birch combination was mainly shear failure in the core. The cores were broken or had sliding surfaces, while the failure mode of the MDF and birch combination was mainly shear failure of the core at both ends. Although the compression properties of the MDF and birch combination were better, the specific strength and modulus of the plywood and birch combination was larger, which align with the characteristics of lightweight and strong strength. The failure mode of the plywood and birch combination was delamination at both ends of the panel or core breakage, which indicated that this combination had better short beam shear properties. The theoretical models of the compressive /short beam shear properties were in good agreement with experimental results obtained for the plywood and birch combination.

The effect of melamine content in melamine modified urea formaldehyde (MUF) resin on durable properties of plywood was investigated using ammonium chloride (NH4Cl) with different melamine/urea (M/U) ratios. The plywood specimens were exposed to laboratory accelerated aging and/or cyclic soak-dry (SD). The experiment results indicated that the melamine contents in MUF resin showed an unobservable effect on the durable properties of MUF resin bonded plywood. The mechanical properties of plywood decreased more severely after accelerated aging test in acidic condition. However, the influence of different curing catalyst contents on mechanical properties and formaldehyde emission of UF resin can be minimized by adding melamine to the resin.

Une étude expérimentale a été menée afin de protéger des attaques biologiques des contreplaqués faits d'essences non durables (hêtre et peuplier), et ce, avec un faible impact environnemental. Des produits de protection à base de tannins et de bore, nouvellement développés afin de réduire le lessivage du bore, ont été sélectionnés pour ce but. Ce système a été utilisé pour protéger les contreplaqués selon deux approches : (1) au niveau de la colle pour remplacer les adhésives à base de formaldéhyde et coller les plis, (2) en traitement des plis avec des formulations plus diluées, les plis étant collés avec des adhésifs mélamine-urée-formaldéhyde. Les données expérimentales de cette thèse peuvent être classées en trois grands groupes : essais chimiques et thermomécaniques des colles tannin-bore, mesure des propriétés physiques et mécaniques, de la résistance biologique avant et après vieillissement des différents panneaux. Les essais chimiques sur les colles tannin/hexamine ont montré que l'addition de bore sous forme d'acide borique peut contribuer à plus de liaisons inter-flavonoids et à ouvrir les cycles pyranes ce qui accélère les réactions de polymérisation. Des analyses thermomécaniques sur les colles contenant des tannins de mimosa et de quebracho ont confirmé que l'addition d'acide borique (1) abaissait le temps et la température de prise, et (2) augmentait les valeurs du module d'élasticité de la colle. L'addition d'une quantité optimale d'acide borique dans la colle à base de tannin augmente les propriétés physiques et la résistance au cisaillement. Une charge excessive d'acide borique (10%) dans la colle est la cause de pertes de propriétés mécaniques et physiques. Bien qu'en faible quantité, l'introduction de l'acide borique dans la colle de tannin amène une protection efficace contre l'attaque fongique, même après un lessivage selon l'EN 1250-2. Les résultats des essais termites montrent que l'acide borique contenu dans la colle cause le plus faible taux de survie des insectes et de perte de masse, mais présentent un fort degré d'attaque selon une cotation visuelle. Aucune amélioration n'a été obtenue lors d'un essai de choix après lessivage. Les contreplaqués faits de plis traités par des solutions tannin-bore ont montré des résistances au cisaillement plus faibles, mais toujours dans les gammes requises pour des applications en atmosphère humide. Des résultats satisfaisants ont été obtenus par les réseaux polymères de tannins, même après une lessivage sévère, vis-à-vis de l'attaque fongique. Les contreplaqués faits de plis traités à l'acide borique seul ont présenté une sensibilité importante à l'attaque biologique après un lessivage. Les résultats des essais termites ont montré un faible taux de survie des insectes et de perte de masse, même après un lessivage sévère, pour les contreplaqués avec des plis traités par des systèmes tannin-bore. Les résultats d'un essai de choix a montré que les termites préféraient se nourrir des témoins quand l'alternative proposée était des échantillons traités avec des systèmes tannin-bore
An experimental investigation was conducted to protect plywood panels made of perishable wood species (beech and poplar) against biological attacks with low environmental impact. The newly developed tannin-boron preservative which was proposed to reduce the leaching of borates was selected for this purpose. This system was used to protect plywood with two approaches: (1) in the glue line to replace formaldehyde based adhesives and gluing wood veneers, (2) pretreatment of wood veneers with the diluted formulations and bonded with melamine-urea-formaldehyde resin The research data in this thesis were obtained from three main groups of experiments: chemicals and thermomechanical testing on the tannin-boron resin, measuring physical and mechanical properties, and different biological tests before and after leaching processes. The chemicals testing on the tannin/hexamine adhesive showed that the addition ofboron, in the form of boric acid, can contribute more inter-flavonoid linkages and the opening of pyran rings which leads to the acceleration of polymerization reactions. Thermomechanical analysis on the adhesives of mimosa and quebracheo tannins confirmed that the addition of boric acid (1) lowered time and temperature of hardening, (2) and increased modulus of elasticity values of the adhesive. The addition of optimal boric acid into the tannin adhesive upgraded physical properties and tensile shear strength. An excess loading of boric acid (10%) in the glue line caused imperfect physical and mechanical features. Despite the low uptake of boric acid but its addition into the tannin glue provided effective resistance against fungal attack even after mild leaching test according to the EN 1250-2. The results of termites test showed that increase in the boric acid content of the adhesive caused the lower survival rate and the weight loss but samples underwent the high level of attack. No improvement against termite attack was obtained after leaching by a choice feeding test. The plywoods made of pretreated veneers by tannin-boron solutions showed partially lower tensile shear strength but still in the range of standards requirements for the humid applications. The satisfactory results were obtained even after severe leaching test against fungal attack with a strong polymeric network of tannin. The control plywoods made of pretreated veneers with boric acid alone solutions presented significant sensitivity against biological attack after leaching test. The results of termite tests showed the lower survival rate and the weight loss even after severe leaching test for the plywoods made of pretreated veneers with tannin-boron systems. The results of choice feeding test showed that termites preferred feeding from the controls when alternative samples were treated with the tannin-boron system. In general the evidence from this study suggests that tannin-boron system can significantly slow down the leaching of boron and it rendered high potential to preserve plywood

Le bois est un matériau naturel qui partage avec d’autres matériaux cellulaires la propriété de pouvoir subir par exemple de fortes déformations de compression avec un effort stable jusqu’à densification. Cette propriété est particulièrement recherchée dans le cas de structures devant subir des chocs. Le bois est ainsi utilisé dans la conception de conteneurs pour produits radioactifs, et dans la structure isolante de méthaniers. Dans ce dernier cas, il peut être soumis à de fortes déformations, à grande vitesse de déformation, et pour des températures ambiantes à cryogéniques. Pourtant, le comportement du bois et plus particulièrement dans le cas des méthaniers, le comportement du contre-plaqué, n’est que très peu étudié dans ces conditions extrêmes de température cryogéniques et de grande vitesse de déformation. De plus, l’influence de la teneur en humidité du bois sur son comportement en sollicitation sévère n’est que très peu connue. Ces sujets sont au coeur de ce travail de doctorat, avec d’abord l’étude du comportement en compression hors plan d’un contre-plaqué de bouleau de la température ambiante à cryogénique de 100K, pour des vitesses de déformation du régime quai-statique à plusieurs centaines par secondes, et pour des humidités du bois de 2 à 15% ; ensuite par des essais en cisaillement qui ont été effectués à grande vitesse de déformation pour une humidité de 8%. La réalisation de ces essais a nécessité le développement de nouveaux montages et la mise au point de protocoles dont les validations sont discutées à partir de comparaisons aux essais normalisés
The wood is a natural cellular material. Like other cellular materials, wood is able to carry a stable load under compression up to the densification. This is a key property for the use of cellular materials and wood based materials for cushioning and choc absorber design. Wood is for example used for radioactive material containers and plywood is involved in the insulation complex of LNG carriers. In this case, plywood may be submitted to high strain rate loads at cryogenic temperature. However, the behaviour of plywood under such extreme conditions is not well established in the literature, nor the influence of the moisture content on the mechanical behaviour in such conditions. In the present study, the out of plane compression behaviour of birch plywood is presented for ambient down to cryogenic temperatures, for strain rate from 0,001 up to 700/s and for moisture contents in the range 2-15%. Shear tests are also presented far various strain rates at ambient temperature and 8% moisture content. The apparatus specially designed and the test protocols are discussed, and the results compared to international standards when available

Tese (doutorado) - Universidade de São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, 2015.
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O presente estudo teve por objetivo determinar as propriedades tecnológicas da madeira de paricá, obtida de árvores de Schizolobium amazonicum Huber ex Ducke aos 14 anos provenientes de duas diferentes áreas de florestas plantadas no estado de Rondônia. Foi amostrado a campo um total de oito árvores, sendo quatro de cada um dos plantios, nos municípios de Rolim de Moura e Parecis. De cada árvore foram obtidas duas toras subsequentes com comprimento de 2,0 m, definidas após a extração de discos removidos ao longo de três posições longitudinais, que foram empregados na determinação da variação radial das características de fibras e vasos e composição química da madeira, e na variação longitudinal da densidade básica e na massa específica aparente, esta última por meio da densitometria de raios x. Da primeira tora foi determinado o rendimento em laminação e das lâminas geradas, produzidos painéis compensados que foram avaliados quanto ao desempenho físico-mecânico. Da segunda tora amostrada, foram confeccionados corpos de prova das porções próximas à medula e casca para a caracterização mecânica da madeira sólida. Os resultados obtidos mostraram que tanto o comprimento das fibras como a espessura de parede celular tenderam a um aumento gradativo, com estabilização na posição a 75% do raio em ambos os plantios amostrados. Ao longo da distância radial a madeira proveniente da área de solo de textura argilosa (Rolim de Moura) tendeu sempre a apresentar valores mais elevados de diâmetro de vasos e área ocupada em relação à madeira da área de solo de textura média e de maior compactação (Parecis), resultando em efeito da proveniência. O teor de cinzas diferiu-se entre as duas áreas, sendo maior na madeira proveniente de Parecis. A densidade básica e massa específica aparente não sofreram influência da proveniência, e mostraram tendência de redução ao longo da porção longitudinal avaliada. Houve influência somente da posição radial nas propriedades mecânicas da madeira, com a maior diferença para o MOE em flexão estática. O rendimento efetivo da laminação das toras foi próximo de 72%, e as propriedades mecânicas dos painéis compensados produzidos tornam os mesmos aptos para aplicação estrutural e naval, segundo normatização relativa a este tipo de produto. Tomando-se por base a variação radial dos parâmetros de comprimento e espessura de parede das fibras, já se observa a presença de madeira adulta no S. amazonicum aos 14 anos nas condições de crescimento avaliadas. Embora os coeficientes indicativos de qualidade das fibras comprovem o potencial da espécie na produção de polpa e papel na idade considerada, o elevado teor de extrativos deve ser considerado nos programas de melhoramento genético. Com exceção da resistência ao cisalhamento, a madeira de paricá aos 14 anos apresentou um incremento nos valores de propriedades mecânicas em relação a outros estudos com esta espécie, principalmente no que se refere à rigidez de sua madeira ao esforço de flexão estática. O rendimento encontrado na laminação e as propriedades dos painéis confirmam a aptidão da espécie na manufatura de compensados.

Abstract : This research aimed to determine the technological properties of the paricá wood obtained from Schizolobium amazonicum Huber ex Ducke trees at age 14 from two different areas of planted forests in Rondônia, Brasil. It was sampled in field a total of eight trees, being four of each one of the plantations in the cities of Rolim de Moura and Parecis. Two subsequent logs with a length of 2.0 m were obtained from each tree defined after the extraction of the disks removed along of three longitudinal positions, which were used for determining the radial variation characteristics of the fibers and vessels and chemical composition of the wood, in the longitudinal variation of the basic density and in the apparent specific mass, being this one by an x-ray densitometry. The first log was determined the yield generated in the peeling process and veneers, producing plywood panels that were evaluated for physical and mechanical performance. From the second log sampled, test pieces of the portions near the cord and bark were made for the mechanical characterization of the solid wood. The obtained results show that both the length of the fiber as the cell wall thickness tended to a gradual increase with stabilization at 75% from the radius in both sampled plantations. Along the radial distance, the wood from the clay ground area (Rolim de Moura) has always tended to show higher values of diameter of vessels and occupied area in relation to the wood ground area of medium texture and higher compaction (Parecis), resulting in effect of the origin. The ash content was granted in two areas, being higher in the wood from Parecis. The density and specific gravity were not affected by the origin of wood, and tended to decrease along the longitudinal portion. There was only influence of the radial position on the mechanical properties of wood, only, with the biggest difference for the MOE in bending. The actual yield of the logs lamination was around 72%, and the mechanical properties of plywood produced make them them suitable for structural and marine applications, according to standardization concerning this type of product. Based on the radial variation of the parameters of length and wall thickness of the fibers, it is observed the presence of mature wood in S. amazonicum at age 14 in the evaluated growing conditions. Though the indicative coefficients of the quality of the fibers demonstrate the potential of the species in the production of pulp and paper at the age considered, the high content of extractives should be considered in breeding programs. Except for the shear strength wood paricá at age 14 showed an increase in the values of mechanical properties relative to other studies of this species, particularly in regard to the rigidity of its wood to bending stress. The yield found in the lamination and properties of panels confirm the suitability of the species in the manufacturing of plywood.

O presente trabalho teve como objetivo avaliar o potencial de utilização da madeira do híbrido Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis para a produção de lâminas e manufatura de painéis compensados. Para realização do estudo foram utilizadas 10 toras de 1,30 m de comprimento, provenientes de 5 árvores coletadas aos 7 anos e 10 meses de idade nos plantios da empresa Pinus Brasil, localizada em Buri - SP. O rendimento do processo de laminação das toras e a qualidade das lâminas produzidas foram avaliados. O delineamento para a produção experimental e avaliação dos painéis compensados constituiu-se de 8 tratamentos arranjados em esquema fatorial, através dos quais foram analisados os efeitos de duas posições de retirada da tora no tronco (A e B), duas gramaturas de adesivo (380 e 420g/m²) e dois tempos de prensagem (8 e 12 minutos). Para cada tratamento foram produzidos 3 painéis compensados, cada qual com 5 lâminas coladas entre si com adesivo à base de fenol-formaldeído. O rendimento médio do processo de laminação das toras, sem casca, foi de aproximadamente 53%, podendo ser considerado bom e compatível com outros resultados encontrados na literatura. As toras A, mais próximas da base das árvores, produziram maior número de lâminas, no entanto, de qualidade inferior em relação às lâminas das toras (B). A massa específica aparente dos painéis estudados foi relativamente baixa em comparação a outros compensados de Pinus, cuja propriedade apresentou valor médio estatisticamente superior para os compensados confeccionados com lâminas das toras A. Os painéis apresentaram boa estabilidade dimensional, sendo que o tempo de prensagem de 12 minutos para a produção dos compensados resultou em diminuição estatisticamente significativa do inchamento em espessura. O tempo de prensagem, gramatura de adesivo e posição da tora influenciaram os valores de resistência da colagem dos painéis, sendo que os maiores valores foram observados para os painéis produzidos com lâminas das toras B, tempo de prensagem de 12 minutos e gramatura de 420g/m². Os valores médios do módulo de ruptura (MOR) e do módulo de elasticidade (MOE) à flexão estática dos painéis foram, respectivamente, compatíveis e inferiores quando comparados com os do Catálogo Técnico n°1 Compensados de Pinus (ABIMCI, 2002). Houve efeito do fator posição da tora no MOR paralelo dos painéis e o maior valor médio foi observado para os compensados confeccionados com lâminas das toras da posição A. Houve interação entre os fatores posição da tora e tempo de prensagem para o MOR e MOE perpendiculares, sendo que, de modo geral, os menores valores foram observados para os compensados confeccionados com lâminas das toras B e prensados no tempo de 12 minutos. Conclui-se que a madeira do híbrido estudado apresenta bom potencial para a produção de lâminas e manufatura de compensados. Porém, o emprego desses painéis em produtos que requeiram elevados valores do MOR e do MOE, por exemplo, em formas de concreto, não é aconselhável, porque esses painéis não satisfariam tais requisitos.
The main objective of this work was to evaluate the potential of wood utilization from Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis hybrid for veneer production and plywood manufacturing. This study used 10 logs measuring 1.30m in length, obtained from 05 trees, 07 years and 10 months of age, from plantations located in Buri SP, Brazil. Peeling process yield and quality of veneers produced were evaluated. The experimental design consisted of eight treatments, arranged in a factorial way, being the effects of two log positions (A and B) on the trunk, two adhesive spread rates (380 and 420g/m²) and two press times (8 and 12 minutes). Three plywood panels were produced for each treatment and each panel was constituted of 05 veneers glued with an adhesive based on phenol-formaldehyde. The peeling process yield was approximately 53%, based on logs without bark, and can be considered good and compatible with other results found in the literature. The logs A, closer to the base of the tree, produced a greater number of veneers, but of inferior quality compared to the logs B veneers. The apparent specific mass of the plywood panels was relatively low, compared to other Pines plywood available in the literature, with a superior mean value for the plywood made with veneers of logs A comparing to logs B. The plywood panels showed good dimensional stability. The press time of 12 minutes resulted in significant thickness swelling decrease and the press time, adhesive spread rate and log position, influenced the bonding line strength. The best results of bonding line strength were obtained for the plywood produced with logs B veneers, press time of 12 minutes and spread rate of 420g/m². The static bending properties of the plywood panels studied, modulus of rupture (MOR) and modulus of elasticity (MOE),were compatible and inferior, respectively, compared to other Brazilian-pines plywood. There was an effect of the log position factor on the MOR-parallel-to-grain with best results obtained for plywood panels produced with veneers of logs A. There was interaction between the log position and press time factors on the MOR and MOE, both perpendicular-to-grain, with the lowest values observed for plywood panels produced with log B veneers and press time of 12 minutes. The hybrid pine wood studied has good potential for veneer production and plywood manufacturing. However, the use of these panels in products that require high values of MOR and MOE, for example, in formwork is not advisable, because these panels do not satisfy these requirements.

Orientador: Cristiane Inácio de Campos
Resumo: Nos últimos anos, o estudo do tratamento térmico na indústria madeireira vem chamando a atenção dos pesquisadores por ser mostrar como uma proposta de preservação sustentável em comparação aos tratamentos químicos tradicionalmente realizados. Com base nisto, este trabalho teve por objetivo avaliar o desempenho do painel compensado produzido com lâminas termorretificadas e coladas com a resina poliuretana à base de óleo de mamona, uma alternativa para substituição do adesivo fenol-formaldeído, que possui a vantagem de ser de origem natural e de não liberar substâncias nocivas ao homem e ao meio ambiente. O processo de termorretificação foi realizado em três diferentes temperaturas (160, 180 e 200°C) e para duas formas de tratamento (prensa e estufa). As alterações ocorridas nas lâminas, após o tratamento, foram avaliadas por meio de testes de rugosidade, utilizando um perfilômetro, e de molhabilidade pelo método de gota, utilizando um goniômetro, os quais mostraram que com o aumento da temperatura as lâminas ficaram menos rugosas e molháveis. O método prensa se mostrou mais efetivo para realizar a termodegradação da madeira na análise do teor de extrativos totais realizado seguindo a norma TAPPI T-257:2012. As alterações verificadas na lâmina impactaram as propriedades físico-mecânicos do painel acabado que foram avaliadas por meio de ensaios recomendados por documentos normativos brasileiros: massa específica aparente (ABNT NBR 9485:2011), inchamento em espessura (ABNT NBR 95... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In recent years, the study of heat treatment in the wood industry has been attracting the attention of researchers as a proposal for sustainable use compared to the traditionally performed chemical methods. Based on this, this work aimed to evaluate the performance of plywood panel produced with heat-treated veneers and glued with a castor oil-based polyurethane resin, an alternative to replace the phenol-formaldehyde adhesive. The advantage of using polyurethane resin is its natural origin and do not release harmful substances to man and the environment. The heat treatment process was carried out at three different temperatures (160, 180 and 200 ° C) and for two forms of treatment. The changes occurred in the veneers, after treatment, were evaluated by roughness tests and wettability, using a goniometer. As the temperature increased, the veneers became less rough and wettable. The press method proved to be more effective to perform the thermo-degradation of wood in the analysis of the total extractive content carried based a TAPPI T-257: 2012 norm. The changes verified in the veneer impacted the physical-mechanical properties of the finished panel, which were evaluated through tests recommended by Brazilian normative documents: density (ABNT NBR 9485: 2011), thickness swelling (ABNT NBR 9535: 2011), moisture (ABNT NBR 9484: 2011), water absorption (ABNT NBR 9486: 2011 ), static bending test (ABNT NBR 9533: 2013) and glue shear strength (ABNT NBR ISO 12466-1: 2012). It was fo... (Complete abstract click electronic access below)
Mestre

Expanding on the theme of bulk waves from the previous chapters, we will examine the problem of plane wave sound propagation in layered media. We assume we have an finite stack of planar layers with perfect, rigidly bonded planar interfaces, but infinite in their lateral extent. The problem has significant industrial interest. Most practical composite laminates are composed of layers of uniaxial fibers and plastic, i.e., plies, whose fiber orientation directions vary from ply to ply through the thickness of the laminate. The mechanical purpose of this directional variation is to render the product stiff and strong in all in-plane directions, much as plywood is layered in cross-grain fashion. Almost no practical composite would be fabricated as a uniaxial product, because of the low bending strength normal to the fiber direction. Instead, various types of layering have been devised to give either tailored stiffness for a specific purpose or approximate in-plane isotropy, also known colloquially as a “quasi-isotropic” laminate. In fact, the approximate isotropy is achieved only in the plane of the plies, because the out-of-plane direction still has significant and unavoidable stiffness differences, since it contains no fibers. The scale of the layering is also important. When the laminations are fine, i.e., when each directional lamina is no thicker than an individual ply as we go through the thickness, only acoustic waves of relatively short wavelength will be able to discern the effect of the layering. At longer wavelengths, the laminate may behave more like an effective medium, still anisotropic, but with averaged elastic properties. On the other hand, if each lamina contains multiple numbers of individual 1/8-mm plies, then the frequency at which an acoustic wavelength approaches the layer thickness will be proportionately lower. This is an important distinction, because it suggests the point at which the layering must be treated as a discrete substructure in order to develop an accurate description of waves in a layered medium. The situation is illustrated schematically in Fig. 6.1. The figure illustrates laminations for a quasi-isotropic composite.

The present study belongs to a broader investigation aiming to reduce noise emissions in nail guns. This noise reduction objective may be achieved by nail gun concept design improvements. However, modifying the tool design requires precise understanding of it dynamics. Therefore a dynamic model of the system including accurate predictions of the tribo-dynamic interactions at the wood-nail interface generating the penetration resistance forces (PRF) appears to be essential. Since different wood products possess different structural/material properties, PRF is first evaluated for various types of wood product individually. Ref. [1] develops the PRF modeling strategy and examines the nail penetration process for plywood samples. The present paper proposes an empirical model predicting PRF imposed on nails when penetrating particle board (PB) at quasi-static velocities (20–500 mm/min range). A universal testing machine (MTS) is used to drive the nails into the wood samples. Each wood sample is composed of five panels PB screwed together. The sample size is chosen to reduce the boundary influence on the penetration process and to avoid the complete perforation of the sample. To eliminate the possible acceleration influence, the penetration speed is maintained at constant amplitudes. The MTS machine measured PRF as a function of the position. The objective is to prepare a formulation predicting PRF as a function of nail position. In order to extend the prediction formula application range, the analysis reduces the studied factors to dimensionless parameters. The analysis shows that the PB fabrication process results in panels presenting three regions of different hardness modulus. As a result, at the region transitions the PRF curves show large amplitude fluctuations. This layered heterogeneity makes the development of a high precision prediction model representing various nail sizes very difficult. Nevertheless, the final model produces PRF evaluations with overall precision greater than 88% for most of the nail penetration.

As LNG carriers become larger and new operating conditions are being designed, it is essential to develop a new procedure for the strength evaluation of a membrane-type LNG containment system under sloshing loads. The conventional comparative method based on existing service experiences and previous damage cases is currently used in most cases, but this method is only valid for designing new LNG carriers with similar size and type of existing ones. In this study, an analytical solution of acoustic-solid interaction has been derived and a simple 2D coupled acoustic-solid model has been simulated to investigate hydro-elastic effects for the verification purpose. After validation of FE modeling, a coupled model considering the fluid-structure interaction between LNG and containment system has been developed for structural analysis of LNG Mark III containment system. For LNG Mark III containment system, nonlinear dynamic FE analysis under sloshing impact pressure has been conducted using the fluid-structure coupling model. In FE simulations, the hydro-elastic effect in structural response has been studied through considering LNG as an acoustic medium, foam as a visco-elastic material, plywood as an orthotropic material, and mastic as an isotropic material. Parametric study has also been done to investigate the effects of material properties and loading patterns on hydro-elastic response in the coupled fluid-structure model. Based on FE results and experimental data, the strength of LNG Mark III containment system has been evaluated in terms of acceptance criteria. Finally, the new procedure has been developed for the strength evaluation of membrane-type LNG containment systems.