Modulus Of Rupture In Bending Research Articles

Optimization of parameters for vacuum heat modification of Cupressus funebris wood

A full factorial experiment was conducted to analyze the main and interaction effects on the physical and mechanical properties of Cupressus funebris Endl. wood subjected to vacuum heat modification. The response variables evaluated were mass loss rate (ML, %), moisture resistance (MR, %), and modulus of rupture in bending (MOR, MPa). The results reveal significant variations in the effects of modification time, holding temperature, and vacuum pressure as independent factors, along with varying degrees of interaction effects among them. Simplifying the analysis model, a regression equation was derived to describe the relationship between the response variable (mass loss rate) and the factors: The model achieved an R-squared value of 96.0% and an R-squared (predicted) value of 73.7%, indicating good overall predictive performance. Optimal process parameters for mid-temperature vacuum heat modification of cypress were determined based on the mass loss rate and modulus of rupture (MOR), resulting in a modification temperature of 120 °C, holding time of 5 h, and a pressure intensity of 0.1. The reliability of the full factorial experiment was further confirmed through orthogonal testing.

Particleboards from Recycled Wood

The effective recovery of wood waste generated in wood processing and also at the end of wood product life is important from environmental and economic points of view. In a laboratory, 16 mm-thick three-layer urea–formaldehyde (UF)-bonded particleboards (PBs) were produced at 5.8 MPa and 240 °C and with an 8 s/mm pressing factor, using wood particles prepared from (1) fresh spruce wood (C), (2) a mixture of several recycled wood products (R1), and (3) recycled faulty PBs bonded with UF resin (R2). Particles from spruce wood were combined with particles from R1 or R2 recyclates in weight ratios of 100:0, 80:20, 50:50 and 0:100. In comparison to the control spruce PB, the PBs containing the R1 recyclate from old wood products were characterized by lower thickness swelling after 2 and 24 h (TS-2h and TS-24h), lower by 18 and 31%; water absorption after 2 and 24 h (WA-2h and WA-24h), lower by 33 and 28%; modulus of rupture in bending (MOR), lower by 28%; modulus of elasticity in bending (MOE), lower by 18%; internal bond (IB), lower by 33%; and resistance to decay determined by the mass loss under the action of the brown-rot fungus Coniophora puteana (Δm), lower by 32%. The PBs containing the R2 recyclate from faulty PBs were also characterized by a lower TS-2h and TS-24h, lower by 45% and 59%; WA-2h and WA-24h, lower by 61% and 51%; MOR, lower by 37%; MOE, lower by 17%; and IB, lower by 33%; however, their biological resistance to C. puteana was more effective, with a decreased Δm in the decay test, lower by 44%.

Characteristics of particleboard manufactured from bamboo shoot sheaths

This study emphasizes on the physical, mechanical, and thermal properties of single-layer particleboard manufactured from bamboo shoot sheaths. Particleboards were produced through the hot-pressed process and glued together by Diphenylmethane Diisocyanate (MDI) adhesive. This is in order for producing specified densities of boards as 400-kg, 600-kg, and 800-kg per m3. The raw material was sieved into four sizes: No.1-No.4 mesh. The particleboards were used to find board density, water absorption, thickness swelling, modulus of elasticity, modulus of rupture in bending, and internal bonding according to the JIS standard. Coefficients of thermal conductivity (k) of boards were discovered by a heat flow meter in steady-state conditions. The results showed that the particleboard performed outstandingly in terms of tensile strength perpendicular to the surface (internal bonding) and low thermal conductivity. However, there were some weaknesses found from their characteristics that were high water absorption and thickness of swelling, low modulus of elasticity and modulus of rupture comparing to standard criteria. The results also indicated that bamboo shoot sheaths, the agricultural residue, can be produced as particleboard, and are appropriate for an indoor heat insulator, but further investigation is required to improve the strength and durability of the particleboard.

Effect of laminated structure design on physical and mechanical properties of laminated bamboo sliver lumber

Laminated structure design is one of the significant factors that affect the physical and mechanical properties of laminated bamboo sliver lumber (LBSL). Eight patterns of assembly for 5-ply LBSL (LLLLL, LLVLL, LVLVL, LVVVL, LLV’LL, LV’LV’L, LVV’VL, and LV’VV’L) were prepared in this study; L represents one horizontal layer of the bamboo-sliver veneer, V represents the layer that is vertical to L, and V’ represents the layer at an angle of 45 ° to the L (or V). The objective of this study was to investigate the exclusive effect of the laminated structure design on the performance of the LBSL, rather than the multiple effect of the number of plies, chemical components, matter content, etc. The results indicated that the bending modulus of elasticity (MOE), bending modulus of rupture (MOR), impact strength, tensile strength, and compressive strength decreased with the decrease in number of layers of ply, for the following levels of L-ply: 5-L-ply (LLLLL), 4-L-ply (LLVLL, and LLV’LL), 3-L-ply (LVLVL, and LV’LV’L), and 2-L-ply (LVVVL, LVV’VL, and LV’VV’L). For the LBSL with the same number of L layers, those which had more V’ layers possessed better properties, due to the action of the parallel component of the force of the V’ layer. The values of absorption swelling rate, breaking strength, and displacement indicated that the LBSL with higher structural complexity achieved poorer underwater dimensional stability, but better single-bolted connection performance.

Influence of thermo-vacuum treatment on bending properties of poplar rotary-cut veneer

The present paper investigates the influence of thermo-vacuum treatment at 170, 190 and 210 °C on the mechanical and physical properties of poplar wood rotary-cut veneers obtained from two different poplar clones (’I-214’ and ’Lena’). The modulus of rupture in bending was determined according to a method derived from European Standard EN-310 and previously validated by the authors, while the density was determined on the basis of EN-323. With both clones no significant decrease was recorded either in bending strength or in density with treatment temperatures up to 190 °C. On the contrary, at 210 °C a highly significant decrease in modulus of rupture (’I-214’: -18%; ’Lena’: -15%) was recorded; the density showed a similar, though lower, trend (’I-214’: -5 %; ’Lena’: -8.5 %).

Effects of log position in the stem and commercial thinning on jack pine chip dimensions produced by a chipper-canter

Fifteen stems of jack pine (Pinus banksiana Lamb.) coming from three commercial thinned (CT) plots (control, moderate, and intensive thinning) in the Abitibi-Temiscamingue region, Canada, were cross-cut into three 2.4 m length sections: bottom, middle, and top logs. Logs were processed with a chipper-canter at three cutting widths (CW 12.7, 19.1, and 25.4 mm), producing chips and a three faced cant. Chips were assessed by thickness, width, and length. Knot characteristics [total knot number (TKN) and area (TKA)] were assessed in the three cant faces. Growth ring attributes [earlywood density, latewood density (LWD), ring density (RD), earlywood proportion (EWP), ring width, and rings per mm], mechanical properties (shear, splitting, modulus of elasticity and modulus of rupture in bending), and basic density were evaluated on samples obtained within each CW area. The weighted mean chip thickness (WCT) was significantly affected by the log position in the stem (LPS) and CW. WCT increased as CW increased. Jack pine produce thicker chips than black spruce, when processed under the same cutting parameters. Thickness of chips coming from bottom and middle logs was similar due to a greater taper of the bottom log, which slightly increased this dimension. Thickest chips were produced in the top log due to a higher TKA and TKN towards the top of the stem. Multiple linear regressions showed that TKA, CW, and RD were significant predictors of WCT. Chip size distributions were significantly affected by the CT, LPS, and CW. Thinned stands logs appeared to produce smaller chips than natural stand logs. Moreover, chip thickness distribution was affected primarily by TKA and EWP, while the width and length distribution was mainly affected by EWP, LWD, and TKN. Chip size in jack pine is to some degree determined by knot attributes, growth ring characteristics, and wood density of the raw material. These results suggest the potential advantage of sorting logs prior to chipping, either by species, LPS and/or provenance (thinned or natural stands).

Caracterização de argilas calcárias utilizadas na produção de revestimentos cerâmicos no Estado de Sergipe - Brasil

Resumo O presente trabalho tem por objetivo caracterizar quatro argilas diferentes utilizadas na produção de revestimento cerâmico do tipo BIIb no Estado de Sergipe, Brasil. As argilas foram caracterizadas por difração de raios X, fluorescência de raios X, análise termogravimétrica, análise térmica diferencial, distribuição de tamanho de partículas, limites de Atterberg e dilatometria. A partir dos resultados obtidos foi possível detectar concentrações de calcita entre 1,1 e 13,7%, a depender da origem da argila. Esta informação é determinante para ajustes no ciclo de queima e previsão da energia mínima para que a sinterização ocorra. Foram produzidos corpos de prova por prensagem uniaxial em matriz retangular de 120 mm x 56 mm x 6 mm a uma pressão de 28 MPa, os quais foram queimados a 1130 oC com ciclo de queima de 23 min e patamar de 3 min. Os corpos de prova foram caracterizados quanto à absorção de água e módulo de ruptura à flexão, e sua microestrutura foi investigada por microscopia eletrônica de varredura. Através dos resultados, foi possível confirmar a correlação entre a formação de fase líquida e redução de porosidade nos corpos cerâmicos sinterizados a 1150 oC. As energias de ativação para o processo de sinterização foram determinadas a partir dos ensaios dilatométricos e os resultados mostraram que, à medida que se diminui o teor de calcário combinado com o aumento do teor de materiais fundentes, a sinterização ocorre em temperaturas mais baixas, resultando em menores gastos energéticos no processo de produção.

The Effect of Joint Form and Parameter Values on Mechanical Properties of Bamboo-Bundle Laminated Veneer Lumber (BLVL)

Bamboo-bundle laminated veneer lumber (BLVL) was produced by joint lengthening technology. The objective of this study was to evaluate the effect of joint form and the values of key parameters on mechanical properties of BLVL. Two joint forms, i.e., finger joint and scarf joint, and two corresponding joint parameters, i.e., finger length and scarf angle, were investigated in laminates. The results indicated that the mechanical properties of jointed BLVL were reduced in comparison to those of BLVL without joints. For finger-joint form, the BLVL member with 14 mm fingers achieved better compressive strength, bending modulus of rupture (MOR), and tensile strength than 19 and 25 mm ones. For scarf-joint form, the 30° scarf-jointed member exhibited the highest bending modulus and tensile modulus of rupture (MOR) in this study, then followed the 45° and 60° ones. The 60° scarf-jointed BLVLs were better than 30° and 45° groups in compression strength. Synthesis of the testing results revealed that finger-jointed BLVLs achieved better bending modulus of rupture than scarf-jointed ones.

Feasibility Study on the Production of Particleboard from Maize Cobs, Rice Husks, and Groundnut Shells Using Acacia Mimosa Tannin Extract as the Bonding Adhesive

AbstractIn recent years, depleted resources and environmental concerns have stimulated research in renewable and recyclable materials for particleboard production. This paper presents the research work on the production of particleboards using maize (Zea mays) cobs, rice (Oryza glaberrima) husks, and groundnut (Arachis hypogaea) shells, which are abundantly available as agricultural residues. The goal of this project was to study the feasibility of medium-density particleboard panels made of agricultural residues for use as internal partition wall cladding in residential buildings. The panels of densities between 600 and 900 kg/m3 were produced using a natural-based adhesive from acacia mimosa tannin extract and hexamine. Some other parameters like the moisture content (after adhesive application) and the press temperature were varied during the production so as to investigate their effect on some mechanical and physical properties like internal bond strength, bending modulus of rupture, swelling, and har...

Development of structural laminated veneer lumber from stress graded short-rotation hem-fir veneer

The key objective of this work was to investigate the feasibility of using short-rotation western hemlock (Tsuga heterophylla (Raf.) Sarg) and amabilis fir (Abies amabilis (Dougl.) Forbes) from coastal Britich Columbia, Canada for manufacturing structural laminated veneer lumber (LVL). Fourteen hem-fir logs were sampled, bucked and conditioned. Hem-fir veneer was then peeled, clipped, dried and visually graded. Combined hem-fir veneer was further segregated into three E grades based on dynamic modulus of elasticity (MOE). LVL billets were manufactured from each E grade and from two grade mixes, and evaluated for flatwise and edgewise bending MOE and modulus of rupture (MOR), and longitudinal shear strength. The results demonstrated that hem-fir veneer visual grade yield was about 15% B with the remainder C. No correlation existed between hem-fir veneer visual grades and E grades. Hem-fir LVL made from high E1 grade, medium E2 grade and low E3 grade could meet 2.2E, 1.8E and 1.5E product market requirements, respectively. Higher E grade veneer yielded higher LVL bending MOE, but not necessarily higher LVL shear strength. A good correlation was found between the LVL bending MOE and veneer mean MOE, and between the LVL bending MOR and MOE. Thus, the bending performance of the hem-fir LVL can be predicted based on veneer E grade and product lay-up. Pressing time changed clearly with the LVL lay-up with higher E grade requiring longer pressing time. Pressing time of mixed grade LVL fell within the times required for the two single grade lay-ups. Mixed grade LVL had a greater enhancement in flatwise than in edgewise, and was therefore more suitable for fabricating flanges of I-joists. Using a grade mix in the product lay-up allows low E grade veneer to be fully utilized for increased value recovery. The results of this study implied that without species segregation, the combined short-rotation hem-fir veneer can be successfully stress graded to manufacture structural LVL for building applications.

Study on effects of wood fiber content on physical, mechanical, and acoustical properties of wood-fiber-filled gypsum composites

The Acoustical model of wood-fiber-filled gypsum composites panel is presented. The transmission loss coefficients of the composite structures were calculated by an approximated approach. However, the physical and mechanical properties of board specimens including; water absorption, thickness swelling, bending modulus of elasticity, bending modulus of rupture, internal bond, and compression parallel to the surface obtained experimentally. Finally, the effects of wood fibers to gypsum mixing ratios on physical, mechanical and acoustical properties of composite flat structures were investigated and data analysis was done by use of statistical methods.

Reactive maleic anhydride polyolefins (MAPOs) in oriented strand board. Part 2: Influence on physical and mechanical properties

Abstract The use of reactive polyolefin and phenol formaldehyde (PF) resin blends to improve the moisture durability of oriented strand composite (OSC) panels was investigated. Test panels were hot pressed with adhesive blends consisting of varying proportions of PF and maleic anhydride polypropylene (MAPP) anionic emulsion, and their physical and mechanical properties were evaluated. The addition of MAPP did not significantly affect the modulus of elasticity (MOE) of the panels, but reduced the modulus of rupture in bending (MOR) for 12% moisture content (MC) and 24-h soak specimens. An increase in PF content significantly improved the MOE and MOR of specimens subjected to the environment. Adding MAPP reduced internal bond strength, particularly at higher PF levels. The addition of MAPP and raising PF levels significantly reduced water absorption and thickness swelling of the panels. At higher MAPP levels, the water vapor transmission in OSC as well as the permeance of the material, was reduced. Composite board equilibrated to lower MC with increasing MAPP content in the resin blend. The results indicate that increasing the PF content is the most effective method of improving both moisture resistance and the mechanical properties of OSC; addition of MAPP improves the moisture resistance of the panels, but significantly reduces their mechanical properties.

INFLUENCE OF AGE AND HEIGHT POSITION ON COLOMBIAN GUADUA ANGUSTIFOLIA BAMBOO MECHANICAL PROPERTIES

The age of bamboo is a key factor that affects its mechanical properties. Bamboo Guadua angustifolia kunt (Guadua a.k.) has been used as a construction material in America, but the influence of the age and height position of the culm on the mechanical properties has not been studied in detail. In this study, selected mechanical properties of Guadua a.k from 2 to 5 year old culms, located at different heights, were investigated using international standard test procedures (ISO 22157). Based on the experimental results, it was found that the top portion (sobrebasa) showed the maximum strength and modulus of elasticity compared to the other portions, since this portion of bamboo has higher density. More over, density of Guadua a.k. culm has more influence in modulus of rupture in bending, than in any of the other studied mechanical properties. Regardless of the culm height, it seems that the mature age of Guadua angustifolia kunt is reached between 3 and 4 years old, because the mechanical properties at those ages were the highest and remained almost constant, whereas the mechanical properties of the culms at the age of 5 were the lowest.

MANUFACTURING OF WOOD FROM RICE STRAW

Rice straw was used as an alternative raw material to obtain cellulosic's pulps. Pulping was done by using classics reagents as soda (with anthraquinone and parabenzoquinone as additives), potassium hydroxide and Kraft process. The holocellulose, α-cellulose and lignin contents of rice straw (60.7, 41.2 and 21.9 wt%, respectively) are similar to those of some woody raw materials such as pine and eucalyptus, and various non-wood materials including olive tree pruning, wheat straw and sunflower stalks. In this paper, rice straw composite boards were manufactured as using the method used in the wood-based panel industry. The raw material, rice straw, was chosen because of its availability. The manufacturing parameters were: a specific pressure of 15, 20, 30,40, and 50 bar, and a rice straw content (15/100, 20/100, 30/70,40/100, and 50/100 by weight of UF/ rice straw) A commercial urea–formaldehyde adhesive was used as the composite binder. The composite boards made from a random cutting of rice straw. The experimental investigation indicated that the optimum particleboard properties are obtained with a mixture ratio of 350 gm UF(Urea-Formaldehyde), pressure 40 bar, 12 mm thickness, the bending modulus of rupture (MOR) of the rice straw composite is 240 kg/cm2 and a density of 1250 kg/m3.When the intended use of these particleboards is as wood panels.

Models for predicting lumber bending MOR and MOE based on tree and stand characteristics in black spruce

In this study, a stepwise method was introduced to identify the best variables for predicting lumber static bending modulus of elasticity (MOE) and modulus of rupture (MOR) based on stand and tree characteristics in black spruce (Picea mariana). In the initial development of the technique, the two equations were fitted independently using ordinary least squares (OLS). A test for cross-equation correlation using black spruce data showed highly significant correlation between the two equations. Since the cross-equation correlation exists between the two equations, more efficient parameter estimation can be achieved through joint-generalized least squares, better known as seemingly unrelated regression (SUR). A simultaneous system of two equations was derived for black spruce. The two methods were evaluated and compared for some statistical parameters. The results indicated that there is a small difference between the two methods, but parameter estimates from seemingly unrelated regression estimation had smaller standard errors in all cases as compared to those from ordinary least squares estimates. Therefore, the system estimation methods theoretically perform better for simultaneously interdependent systems of equations and the appropriate system estimation approaches are recommended for estimating coefficients in simultaneously interdependent systems of forestry equations.

Rice straw-wood particle composite for sound absorbing wooden construction materials.

In this study, rice straw-wood particle composite boards were manufactured as insulation boards using the method used in the wood-based panel industry. The raw material, rice straw, was chosen because of its availability. The manufacturing parameters were: a specific gravity of 0.4, 0.6, and 0.8, and a rice straw content (10/90, 20/80, and 30/70 weight of rice straw/wood particle) of 10, 20, and 30 wt.%. A commercial urea-formaldehyde adhesive was used as the composite binder, to achieve 140-290 psi of bending modulus of rupture (MOR) with 0.4 specific gravity, 700-900 psi of bending MOR with 0.6 specific gravity, and 1400-2900 psi of bending MOR with a 0.8 specific gravity. All of the composite boards were superior to insulation board in strength. Width and length of the rice straw particle did not affect the bending MOR. The composite boards made from a random cutting of rice straw and wood particles were the best and recommended for manufacturing processes. Sound absorption coefficients of the 0.4 and 0.6 specific gravity boards were higher than the other wood-based materials. The recommended properties of the rice straw-wood particle composite boards are described, to absorb noises, preserve the temperature of indoor living spaces, and to be able to partially or completely substitute for wood particleboard and insulation board in wooden constructions.

Development of Low-Cost Wheat-Straw Insulation Board

Insulation boards suitable for buildings with solid masonry walls that lack cavities necessary for loose-fill insulation have been fabricated and tested for use in developing countries. The boards were made at low density, 80 to 160 kg/m3 (5 to 10 lb/ft3), and have suitable thermal properties for an air-based insulation, with a thermal resistivity of 21 to 28 m·K/W [R3 to R4 per inch (h·ft2·° F/ Btu·in)]. The initial effort focused on straw insulation boards suitable for use in buildings with solid masonry walls that lack cavities necessary for loose-fill insulation. The possible methods of fabrication initially evaluated were (1) containing the straw in panels with wire and battens, (2) pulping the straw, and (3) binding with adhesive. Starch, polyvinyl acetate (PVA,) and sodium silicate were evaluated as adhesives for both uncut and shredded straw. Methods of application included spraying, foaming, and dipping, at various adhesive-loading rates. Small samples were formed at a range of densities and tested for structural and thermal properties. All three approaches can succeed structurally and thermally, but are unable to compete economically with existing insulation board. A final batch of boards was made by spraying methane di-isocyanate (MDI), a synthetic resin, into a rotating tumbler that contained shredded straw. The boards, made over a range of densities and resin contents, and using straw with and without the fine particles, were tested thermally and structurally. Good mechanical properties were obtained at resin contents as low as 2% by mass. At densities of 128 and 160 kg/m3 (8 and 10 lb/ft3), the boards had thermal resistivities of 24 to 26 m2·K/W (3.45 to 3.7 h·ft2·°F/ Btu·in). The pressure required to compress the 160 kg/m3 (10 lb/ft3) boards to 10% of their original thickness was approximately 100 kPa (15 psi), and the modulus of rupture in bending was about 340 kPa (50 psi). Removing the fine particles from the straw improved board strength markedly. The final boards at a density of 160 kg/m3 (10 lb/ft3) and 2 to 4% resin content have an estimated materials cost of $1.22 per unit of thermal resistance (m2·K/W) per square metre of area (2¢ per R per ft2). This cost is substantially less than either the cost of the expanded polystyrene available in Pakistan or the retail cost of any rigid board insulation sold in North America.

Effect of growth rate on the anatomy, specific gravity, and bending properties of wood from 7-year-old red alder (Alnus rubra)

Understanding the association between growth rate and wood properties is of practical importance to maximizing and sustaining wood and fiber production. Anatomical characteristics, specific gravity, and bending properties were determined at breast height for thirty 7-year-old trees with varying growth rates, from a red alder (Alnus rubra Bong.) plantation. Wood was sampled from the growth ring with a cambial age of 5 years. Growth varied from 2.0 to 9.3 mm/year (ring width), or 264 to 3350 mm 2 /year (ring area). We analyzed the relationship between growth rate, in terms of both annual ring width and area, and each wood property. Because both measures of growth rate yielded the same qualitative results, we only used ring width in our analyses. Regression analysis showed that growth rate had no effect on specific gravity, the modulus of elasticity in bending, the modulus of rupture in bending, fiber diameter, or the proportion of growth ring that was fiber or vessel. Fiber length, vessel diameter, and ray proportion, however, were positively correlated with growth rate. Fiber-wall thickness and axial parenchyma proportion decreased slightly with growth rate. The results indicate that the growth rate of A. rubra trees can be increased through silvicultural practices with few negative effects on wood and fiber quality, at least in the juvenile wood zone of the stem.

Potential of plantation-grown eucalypts for structural sawn products. II.Eucalyptus nitens(Dean & Maiden) Maiden andE. regnansF. MuelL

Summary Plantation-grown 15- to 29-year-old Eucalyptus nitens (Dean & Maiden) Maiden and 15- to 30-year-old E. regnans F. Muell. from Tasmania and Victoria were tested as a resource for structural sawn products. Back-sawn products were dried, dressed, visually stress graded, and subjected to a four-point bending test, and small clear specimens were tested under central point loading. Knots in both species were more frequent and larger than in material from natural forests, and significantly decreased the modulus of rupture in bending (MOR) and modulus of elasticity (MOE) in most cases, determining the structural grades of 2400 mm boards. There was a marked incidence of decay in E. regnans trees. Satisfactory drying of 2400 mm boards was achieved and most internal checking did not significantly affect MOR and MOE. Strength groupings suggested SD6 for E. nitens and SD5 for E. regnans. The in-grade testing allocated F5 for E. nitens and F7 for E. regnans. The stress grades derived from the ingrade testing ag...

Some Anisotropic Properties on the Strength of the Plywood

The calculation formulae ralating the stress in bending of the laminated wood-beam were checked by tests and verified their appricability to the plywood.The anisotropic properties of strength of the plywood can be represented by the ratios of AE=E90/E0, BE=EB90/EB0 and NR=R90/R0 where E0, EB0 and R0 denote respectively the elastic moduli in edgewise tension or compression, the elastic moduli in bending and modulus of rupture in bending of plywood parallel to the face grain, and E90, EB90 and R90 denote those values of plywood perpendicular to the face grain. These values in the cases of 3-ply, 5-ply and 7-ply plywood of LAUAN which are constructed from single species and have symmetetrical construction to their core are evaluated by the computed results using the basic strength of veneer, and the anisotropic properties of them are discussed.