Inter-and Intraspecific Differences in Physical and Mechanical Properties of Wood from Sclerocarya birrea and Anogeissus leiocarpus (original) (raw)
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Physical and strength properties of Sudanese Anogeisus leiocarpa (CD) Gill and Commiphora africana (A. Rich.) wood from North Darfur State were studied to determine their physical and mechanical properties as potential wood species for North Darfur State and Sudan. Moisture content, wood density (basic and oven-dry), Bark-to-wood ratio by volume and radial and tangential shrinkage were determined. Static bending strength, compression strength parallel to the grain, the modulus of elasticity (MOE), the modulus of rupture (MOR) and the maximum crushing strength for both wood species were determined. The obtained results have shown low values of moisture content for both wood species due to the relatively low humidity during summer when they were collected. A. leiocarpa has shown a higher average value for oven-dry density (861.0 kg/m) while Commiphora africana has shown a lower oven-dry density 3 (261.0 kg/m). The average bark-to-wood ratio was found to be higher for C. africana (10.23, %) than 3 A. leiocarpa (7.52%). They were all in the normal range for tropical hardwoods. The tangential shrinkage for both wood species was almost double the radial shrinkage. The ratio for tangential to radial shrinkage (T/R) was higher for A. leiocarpa (2.20) and lower for C. africana (1.58). Those properties, in addition to the highest maximum crushing strength make A. leiocarpa a suitable wood for structural works and furniture. C. africana was found to be very brittle during static bending and compression tests. Due to its strength properties it is not suitable for construction or any uses which need strength.
This study was conducted to determine the effect of wood species on physical and mechanical properties of some selected wood in the Tropical Rainforest Ecosystem, Ondo State, Nigeria. The experiment was laid out in Complete Block Design (CBD). . The wood species includes Meliceae excelsa, Khaya ivorensis, Triplochiton scleroxylon, Afzelia africana and Celtis mildbraedii. The wood were machined and trimmed to standard size of 20mm X 20mm X 60mm for the determination of physical properties and 10mm X 10mm X 300mm for mechanical properties. All the samples were replicated five times. The green weight was determined with a digital weighing balance; the longitudinal, radial and tangential axes were measured with a veneer caliper. All samples were oven dried at initial temperature of 70⁰C for 6 hours and thereafter increased to 100⁰ ± C to complete 24 hours. This procedure was repeated until a substantial constant weight was obtained and the physical properties calculated. The test for mechanical properties (modulus of rupture and elasticity-MOR and MOE) were performed on an Improvised Universal Testing Machine. The samples were subjected to three point bending test with varying load. At the point of failure, the force exerted that causes the failure was recorded and the MOR and MOE calculated. The results of this study shows a significant (P=.05) variation in wood density (Afzelia africana>Celtis mildbraedii>Meliceae excelsa>Khaya ivorensis>Triplochiton scleroxylon) The MOR (N/mm 2 ) and MOE (N/mm 2 ) of these wood species indicates that Celtis mildbraedii and Afzelia africana has the highest values (149.94/7088 and 136.71/6313), Khaya ivorensis, Meliceae excelsa and Triplochiton scleroxylon has relatively lower values. The test of selected wood species shows that strength of a timber depends on its species and hence different wood species have different strength characteristics. The results obtained in this study has provided quantitative information on the mechanical properties of selected wood species which can be used in determining the application of these wood for either heavy and for building, construction or for other purposes such as the manufacture of furniture.
Physical and Mechanical Properties of Cupressus lusitanica as a Potential Timber Tree for Sudan
Abstract— The wood of 20-year-old Cupressus lusitanica Mill. from Jebel Marra area Western Sudan was studied to determine its physical and mechanical properties as a potential exotic timber tree. Wood density as basic and on oven-dry density was determined. Bark-to- wood ratio by mass and by volume as well as radial and tangential shrinkage was determined. Static bending tests were carried out and the modulus of rupture MOR and modulus of elasticity MOE were calculated. Impact bending, compression strength parallel to grain, maximum crushing strength as well as shear stress were determined. The obtained results for the mechanical properties were compared with the values for the same cypress species from India and Costa Rica. The results showed that the average value for the oven-dry wood density (513 kg m-3) and the basic density (446.0 kg m-3) were medium but higher than the Indian (434kg m-3) and Costa Rican cypresses. The average bark-to-wood ratios (7.95%by mass and 5.12% by volume) were in the normal range for tropical softwoods. The MOR (693.0 kpa cm-2) was lower than that of the Indian cypress (763.0 kpa cm-2) but higher than for the Costa Rican cypress. The MOE (142.7 kg m-2) indicates good stiffness properties. The compressive strength was higher than for both the Indian and Costa Rican. The shear stress was lower than that of the Indian cypress but similar to Costa Rican. Due to the obtained results the wood of C. lusitanica studied could be considered as a medium density structural and general purpose wood.
Variation of wood density and mechanical properties of blackwood (Acacia melanoxylon R. Br.)
2014
The variation of wood density and mechanical properties with site, tree and within tree (longitudinal and radial) were studied for blackwood (Acacia melanoxylon R. Br.) grown in four sites in Portugal. Twenty trees were randomly selected (40 cm dbh class, 33-51 years of age), sampled at three stem height levels (5%, 35% and 65% of tree height) and three radial positions (10%, 50% and 90% of radius). They were further tested for air-dry density at 12% moisture content, bending strength (MOR), modulus of elasticity (MOE) and compression strength parallel to grain (CS), using ISO standards.
Mechanical Properties of four Lesser-Known Ghanaian Timber Species
2019
The exploitation of timber in Ghana and many parts of tropical Africa is limited to very few of the over 800 known species whose mechanical properties for structural use are unknown. The global demand for these few species with excellent properties in terms of their strength and quality of finishes has led to their over-exploitation and destruction of other less accepted species during logging operations. The structural use of timber is very limited in tropical Africa in spite of its abundance in the forests and its sustainability by cultivation. Considerable discussion has been held about the fuller utilization of tropical forests with particular reference to lesser-known species (LKS), but the problem has remained intractable and very little has been done. One main problem in promoting the LKS is lack of information on their realistic mechanical properties based on structural size dimensions. This paper reports results of research on the mechanical properties of four lesser-known ...
International Journal of Engineering & Technology
Wood is a material used in construction, in instrument making, etc. In Benin, for heavy construction and construction on wetland, species with high technological characteristics are imported. But the performance of these imported species compared to local indigenous or exotic species remains to be verified. Thus, it is necessary to determine the basic technological properties of these species. It is within this framework that we have, on 500mm×20mm×20mm prismatic wood specimens of Anogeissus leiocarpus, Manilkara multinervis and Cylicodiscus gabunensis, used the acoustic method BING (Beam Identification by Non-destructive Grading) of CIRAD-Forest to determine the density Ï, the moduli of Young's modulus E, shear modulus G and the internal friction tan𛿠and then evaluated the modulus of specific stiffness E/Ï. On other 20 mm edge cubic specimens, we evaluated the reference physical properties of density, infradensity, total shrinkage, radial shrinkage, tangential shrinkage...
African Journal of Plant Science
The current study examines the physical and mechanical properties of branch wood from Holarrhena floribunda and Nesogordonia papaverifera, two of Ghana's least researched deciduous species. At an equilibrium moisture content of 12±2%, H. floribunda and N. papaverifera specimens had average density values of 467.53 and 720.80 kgm-3 , respectively. The overall tangential and radial shrinkage was 3.8 and 3.2%, respectively, while the radial shrinkage was 2.8 and 1.8%. For H. floribunda and N. papaverifera, the modulus of rupture was 80.2 and 122.3 N/mm 2 , respectively, whereas the static modulus of elasticity was 8213.8 and 12902.8 N/mm 2. Shear strength parallel to grain was around 11.9 and 16.5 N/mm 2 , whereas compression strength parallel to grain was approximately 36.6 and 52.3 N/mm 2. H. floribunda and N. papaverifera have Janka hardness values of 6.2 and 10.3 N/mm 2 tangentially, and 4.3 and 8.9 N/mm 2 radially, respectively. The qualities of the branch wood of H. floribunda and N. papaverifera were equivalent to those of their stem wood and other known wood species, indicating that they might be used in a variety of wood-related applications.
Mechanical properties of some Indian woods
The paper reports a study of mechanical properties of Indian woods of different species belonging to different botanical families. Tensile strength and compression strengths were measured at normal dried condition. A significant variation in mechanical properties is observed with respect to each species as well as same species of same botanical family. Macro and micro structured variations in wood have been analyzed on the basis of variation in above parameters.
This study was carried out to determine some physical properties of Cola nitida and Funtumia elastica two lesser-known timber species in Ghana that are not used for commercial timber purposes. The basic properties were determined based on British Standard 373 (1957). The main statistical tools used were Descriptive Statistics and Analysis of Variance (ANOVA). Variation in physical properties was analyzed within the trees of the two species. Three trees each per species were used in the study. Results of the study showed that initial moisture content were 66.6% and 79.4% for Cola nitida and Funtumia elastica respectively. The basic density of Cola nitida was 623.8 kg/m 3 and 499.6 kg/m 3 for Funtumia elastica. According to TEDB (1994), Cola nitida is a Medium-Heavy species and Funtumia elastica a Medium Weight species. Mean total tangential shrinkage from green to oven-dry was 7.25 and 6.78% for Cola nitida and Funtumia elastica, respectively. Mean partial tangential shrinkage from g...
Representativeness of wood biomechanical properties measured after storage in different conditions
Trees, 2012
Obtaining representative values of green wood properties is essential for studies investigating the biomechanical aspects of tree development and ecology. Here we compare the biomechanical properties of wood stored in various conditions between their collection in the field and their measurement. The study was performed on a large sample of wood specimens from different tropical species and different location in the trees, representing a wide diversity in wood structures. Elastic and viscoelastic properties are measured on green wood, and measured again after storage in different conditions: immersion in cold water during various durations, storage in an ethanol solution with or without washing in water, and air-drying with or without re-hydration. The systematic and random errors induced by these storage methods are quantified. Storage in cold water is the best way to preserve wood native properties. Soaking in ethanol is a fair alternative regarding elastic properties, but induces a significant change in viscoelastic properties. Air-drying causes important and partly irreversible changes in mechanical properties. However, regarding elastic properties, this change is a systematic bias so that the airdried elastic modulus provides a good basis for comparative studies of green wood stiffness.