scholarly journals Characterisation and grading of four selected timber species grown in Nigeria in accordance with Bs 5268

2021 ◽  
Vol 40 (4) ◽  
pp. 576-583
Author(s):  
U.N. Wilson ◽  
Y.N. Mohammad ◽  
I.S. Mohammed ◽  
F.O. Adeyemi
Keyword(s):  
Mechanical Properties ◽  
Laboratory Data ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Bending Test ◽  
Analysis Tool ◽  
Timber Species ◽  
Parkia Biglobosa ◽  
Distribution Models ◽  
Vitex Doniana

This study presents a development of strength classes for Vitex doniana, Diospyros mespliformis, Parkia biglobosa and Isoberlinia doka, northern Nigeria timber species in accordance with BS 5268-2 (2002) and NCP 2 (1973). The specimens for the experimental measurements were obtained from timber-sheds in Zaria, Kaduna - Northern part of Nigeria. The laboratory experiments were conducted to determine the physical and mechanical properties of the selected timber species. The specimens were prepared in accordance with BS 373 for small clear specimens for the determination of physical and mechanical properties. Flexural strength properties were determined using three point bending test. Adjustment was made on the mechanical properties at moisture content of 12% and 18% in conformity with BS 5268-2 (2002) and NCP2 (1973) respectively. The laboratory data were analyzed using data analysis tool pack in Microsoft excel 2019 to generate the mean, coefficients of variation and theoretical distribution models which form the uncertainty models. Basic and grade stresses were also computed using experimental failure stresses. The selected timber species were then classified using the grade bending stress, density and mean modulus of elasticity obtained. Vitex doniana, Diospyros mespliformis, Parkia biglobosa and Isoberlinia doka were assigned to strength classes D30, D40, C40 and D30 in accordance with BS 5268-2 (2002) respectively. Similarly, in accordance with the NCP 2 (1973), these species belong to N4, N3, N4 and N3 respectively. The results obtained show that Vitex doniana, Diospyros mespliformis and Isoberlinia doka are hardwoods whereas, only Parkia biglobosa is a softwood species.

scholarly journals Determination of Strength Classes of Selected Nigerian Timbers in Accordance with EN338 (2009)

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Idayat O Sholadoye ◽  
Idris Abubakar
Keyword(s):  
Mechanical Properties ◽  
Limit State ◽  
Physical And Mechanical Properties ◽  
Tectona Grandis ◽  
Bending Test ◽  
Timber Species ◽  
Gmelina Arborea ◽  
Permissible Stress ◽  
Four Point Bending ◽  
Four Point Bending Test

Wood has several unique, independent properties. The physical and mechanical properties of wood do vary from species to species and even within species due to environmental conditions during growth. In Nigeria, timber is been grade based on permissible stress (NCP) an upgrade to the limit state is required. A laboratory test was carried out to develop the physical and mechanical properties (four-point bending test) of the timber species in accordance with EN 13153-1, ASTM D143 and EN 408. The strength classification of selected timber was performed according to EN 338 using characteristic value of the material properties in accordance with EN384 from the generated physical and mechanical properties, after being adjusted to 12% (Eurocodes reference moisture content). The timber species considered were Tectona grandis and Gmelina arborea. The result showed Tectona grandis had a higher property than Gmelina arborea and the species were assigned to strength classes of D50 and D35 (hardwoods) respectively. The study shows that the selected timber species are suitable for structural purposes.Keywords: Strength classes, Nigerian timber, Four-point bending test, Tectona grandis, Gmelina arborea

scholarly journals RESEARCH OF PHYSICAL AND MECHANICAL PROPERTIES OF WOOD-FIBER MATERIALS

2020 ◽  
pp. 451-457
Author(s):  
Aleksandr Yur'yevich Vititnev ◽  
Yuriy Davydovich Alashkevich ◽  
Natal'ya Geral'dovna Chistova ◽  
Roman Aleksandrovich Marchenko ◽  
Venera Nurullovna Matygullina
Keyword(s):  
Mechanical Properties ◽  
Wood Fiber ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Production Method ◽  
Strength Properties ◽  
Grinding Process ◽  
Technological Parameters ◽  
Fiber Materials ◽  
Traditional Construction

This paper presents the results of experimental studies of the physical and mechanical properties of wood-fiber boards of the wet production method when regulating the design and technological parameters of the grinding process. This allowed us to determine the influence of the working clearance between the grinding discs and the concentration of fibre mass with the subject to of quality change wood fiber after defibrator using the developed construction of the disc fibrillation action on the physico-mechanical properties of boards. As a result of the experiment, regression models were obtained that adequately describe the studied grinding process and allow predicting the values of physical and mechanical properties of the finished product depending on the established  parameters process. A comparative analysis of the size and quality characteristics of the fiber semi-finished product and its fractional composition when using a developed construction the disc of refiner fibrillation action and a traditional design used in industry is carried out. The preferential efficiency of the grinding process under the fibrillating effect the disc of refiner in comparison with the traditional construction disc of refiner is established. As a result, there is a significant improvement in the quality indicators of the fiber semi-finished product and its composition due to the formation and predominance in the total mass of long and thin, respectively, flexible fibrillated fibers with high tile-forming properties, which allows to increase the strength properties of the product (by 20–25%), without using binding resins.

Thermo Mechanical behaviour of Phenol Novolac Resin and Unsaturated Polyester Toughened Epoxy using nano Bentonite and Silica Nanoparticles

2020 ◽  
Vol 1 (3) ◽  
pp. 77-83
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Silica Nanoparticles ◽  
Moisture Absorption ◽  
Unsaturated Polyester ◽  
Physical And Mechanical Properties ◽  
Bending Test ◽  
Mechanical And Thermal Properties ◽  
Novolac Epoxy ◽  
Industrial Needs

Phenol novolac epoxy resin is a polymer matter which its properties can be modified for industrial needs. In this research, nanocomposites of phenol novolac epoxy resin and unsaturated polyester are made nano Bentonite and silica nanoparticles as filler. For this purpose, effect of nanoparticles percent on nanocomposite formation is studied and their physical, mechanical and thermal properties are obtained. The presence of unsaturated polyester in this process forms a cross-link capable of improving the physical and mechanical properties of epoxy resin. Fracture behavior was determined by a SEM device. Moreover, TGA, DSC, impact tests and bending test were applied for data analysis. When process ability is growing, moisture absorption decreases. Fracture toughness was also evaluated in a stoichiometric network. Physical and mechanical properties improve significantly with increasing nanoparticles. The most important reason for using this nanocomposite is its high resistance to corrosion.

scholarly journals Composites of Rigid Polyurethane Foams Reinforced with POSS

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 336 ◽  
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Krzysztof Strzelec ◽  
Agnieszka Adamus-Włodarczyk ◽  
Agnė Kairytė ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Water Absorption ◽  
Viscoelastic Behavior ◽  
Physical And Mechanical Properties ◽  
Polyurethane Foams ◽  
Bending Test ◽  
Mechanical And Thermal Properties ◽  
Rigid Polyurethane Foams ◽  
Cell Shapes

Rigid polyurethane foams (RPUFs) were successfully modified with different weight ratios (0.5 wt%, 1.5 wt% and 5 wt%) of APIB-POSS and AEAPIB-POSS. The resulting foams were evaluated by their processing parameters, morphology (Scanning Electron Microscopy analysis, SEM), mechanical properties (compressive test, three-point bending test and impact strength), viscoelastic behavior (Dynamic Mechanical Analysis, DMA), thermal properties (Thermogravimetric Analysis, TGA, and thermal conductivity) and application properties (contact angle, water absorption and dimensional analysis). The results showed that the morphology of modified foams is significantly affected by the type of the filler and filler content, which resulted in inhomogeneous, irregular, large cell shapes and further affected the physical and mechanical properties of resulting materials. RPUFs modified with APIB-POSS represent better mechanical and thermal properties compared to the RPUFs modified with AEAPIB-POSS. The results showed that the best results were obtained for RPUFs modified with 0.5 wt% of APIB-POSS. For example, in comparison with unfilled foam, compositions modified with 0.5 wt% of APIB-POSS provide greater compression strength, better flexural strength and lower water absorption.

scholarly journals Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins

2009 ◽  
Vol 20 (2) ◽  
pp. 132-137 ◽  
Author(s):  
Rafael Leonardo Xediek Consani ◽  
Douglas Duenhas de Azevedo ◽  
Marcelo Ferraz Mesquita ◽  
Wilson Batista Mendes ◽  
Paulo César Saquy
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
Knoop Hardness ◽  
Microwave Energy ◽  
Bending Test ◽  
Denture Base ◽  
Acrylic Resins ◽  
The Impact

The present study evaluated the effect of repeated simulated microwave disinfection on physical and mechanical properties of Clássico, Onda-Cryl and QC-20 denture base acrylic resins. Aluminum patterns were included in metallic or plastic flasks with dental stone following the traditional packing method. The powder/liquid mixing ratio was established according to the manufacturer's instructions. After water-bath polymerization at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling and finished. Each specimen was immersed in 150 mL of distilled water and underwent 5 disinfection cycles in a microwave oven set at 650 W for 3 min. Non-disinfected and disinfected specimens were subjected to the following tets: Knoop hardness test was performed with 25 g load for 10 s, impact strength test was done using the Charpy system with 40 kpcm, and 3-point bending test (flexural strength) was performed at a crosshead speed of 0.5 mm/min until fracture. Data were analyzed statistically by ANOVA and Tukey's test (α= 0.05%). Repeated simulated microwave disinfections decreased the Knoop hardness of Clássico and Onda-Cryl resins and had no effect on the impact strength of QC-20. The flexural strength was similar for all tested resins.

scholarly journals INFLUENCE OF DRYING ON THE PHYSICAL AND MECHANICAL PROPERTIES OF WOOD FROM TREES GROWN IN AN AGROFORESTRY SYSTEM

2020 ◽  
Vol 44 ◽  
Author(s):  
Elder Eloy ◽  
Eduarda Bandera ◽  
Tauana Mangini ◽  
Laura da Silva Zanchetta ◽  
Rômulo Trevisan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Eucalyptus Grandis ◽  
Physical And Mechanical Properties ◽  
Agroforestry System ◽  
Bending Test ◽  
Schizolobium Parahyba ◽  
Standard Specimens ◽  
Forced Air ◽  
Air Circulation

ABSTRACT The cultivation of native and exotic species intercropped in an agroforestry system raises the interest for information on the properties of wood. Therefore, different methods are being tested to improve the technological properties of this material, including drying, which causes changes in the physical and mechanical properties of the wood. The present study investigated the influence of drying on the physical and mechanical properties of wood from tree species grown in an agroforestry system. Parapiptadenia rigida (Benth.) Brenan, Peltophorum dubium (Spreng.) Taub., Eucalyptus grandis W. Hill × Eucalyptus urophylla S.T. Blake (hybrid), and Schizolobium parahyba (Vell.) S.F.Blake were the species selected for the study. Three 9-year-old individuals of each of the species were obtained from an agroforestry system. Thirty wood samples (2.5 × 2.5 × 41 cm) were extracted from each species. The wood samples were divided between temperature treatments; 6 samples were used for each heat treatment (control, 120, 150, 180, and 210 °C), which were then dried for two hours in an oven (with forced air circulation). Following the heat treatment, the mechanical properties of wood samples were evaluated to determine the modulus of elasticity and rupture, the tension in the proportional limit, and maximum force according to the ASTM D-143-94 (2000) standard. Finally, the physical properties of the retractability of the wood samples were evaluated according to the NBR 7190 (ABNT, 1997) standard. Specimens used to analyze this variable came from sections of the wood (sample dimensions: 2.5 × 2.5 × 5 cm) not affected by the static bending test. Our findings indicate that, for all species investigated in this study, drying alters the physical and mechanical properties of the wood, with the most significant changes occurring at temperatures between 120 and 180 °C.

scholarly journals Physical and mechanical properties of (Acacia auriculiformis x A mangium) hybrid Acacia

1970 ◽  
Vol 34 (2) ◽  
pp. 181-187 ◽  
Author(s):  
UK Rokeya ◽  
M Akter Hossain ◽  
M Rowson Ali ◽  
SP Paul
Keyword(s):  
Mechanical Properties ◽  
Specific Gravity ◽  
Acacia Mangium ◽  
Physical And Mechanical Properties ◽  
Tectona Grandis ◽  
Acacia Auriculiformis ◽  
Timber Species ◽  
Green Condition ◽  
Natural Crossing ◽  
Academy Of Sciences

The physical and mechanical properties of hybrid Acacia, produced from natural crossing between two introduced timber species (Acacia auriculiformis and Acacia mangium) were studied. The timber hybrid Acacia is of medium dense having specific gravity 0.56 at green condition which is less than that of teak (Tectona grandis). The volumetric shrinkage of hybrid Acacia wood was found greater than that of teak but the specific gravity was found less than that of teak. From the study of physical and mechanical properties it is evident that the species is moderately strong. The species is suitable for making furniture and other household articles. Key words: Hybrid Acacia; Specific gravity; Physical properties; Mechanical properties DOI: 10.3329/jbas.v34i2.6864Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 181-187, 2010

scholarly journals Effects of nano and micro size of clay particles on the compressive and tensile strength properties of self-consolidating concrete

2018 ◽  
Vol 162 ◽  
pp. 02030 ◽  
Author(s):  
Baydaa Alrashedi ◽  
Maan Hassan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Pozzolanic Activity ◽  
Chemical Compositions ◽  
Particle Sizes ◽  
Self Consolidating Concrete ◽  
Clay Particles

Many past studies concerned about using of nanoclay (nC) particles as an active pozzolan to concrete and their influence on the physical and mechanical properties. In this study, the effects of various nanoclay particle sizes and dosages on the compressive and flexural tensile strengths of SCCs were investigated. Progressive nC percentages of 2%, 5% and 8% were replaced with cements and the produced SCCs were evaluated and compared with similar replacement levels of the metakaolin MK which have comparable chemical compositions. The produced SCCs were tested for compressive, flexural tensile and splitting tensile strengths in 28 and 90 days. Results indicated that nC replacement harmed all the studied mechanical properties at 28 days age. After 90 days, however, both compressive and tensile strengths of nC concretes show superior strengths than control concrete and also exceeded MK concretes made of equivalent replacement levels. This behavior demonstrates the pozzolanic activity of the nC particles at later ages and proved to be significantly more effective than early ages.

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