Experimental Study on Properties of Some Lesser Used Seasoned Timber Species in Myanmar

This study investigates the properties of four lesser used seasoned timber species in Myanmar: Inn (Dipterocarpus tuberculatus Roxb.), Kanyin (Dipterocarpus turbinatus), Thit-Sein (Terminalia bellirica Roxb.) and Yamane (Gmelina arborea Roxb.). The experiments are tested according to American Standard Methods of Testing Small Clear Specimens of Timber (ASTM D 143 moisture content is examined in the kiln dried condition. The mechanical properties are done t measure the bending strength, compressive strength parallel to grain, compressive strength perpendicular to grain, and tensile strength perpendicular to grain and shear strength of each species of timber. In addition, the density and moisture content of are also measured for physical properties. Total 600 specimens (30 specimens for each test and species) are measured in this study. The results from experiments are also adjusted to 12% moisture content.


I. INTRODUCTION
Myanmar is a country with a long history of scientific forest management and possessing valuable natural forest resources. Over half of the country is covered with natural forests. So, forest products are the big sources of foreign income.
Wood is different from other construction materials because it grows naturally. Its mechanical properties largely depend on the species, age, location, @ IJTSRD | Available Online @ www.ijtsrd.com | Volume -2 | Issue -5 | Jul-Aug 2018 Myanmar is a country with a long history of scientific forest management and possessing valuable natural country is covered with natural forests. So, forest products are the biggest Wood is different from other construction materials because it grows naturally. Its mechanical properties largely depend on the species, age, location, climate and humidity. Related to its physical properties, wood has different colors and odors. In addition, its unit weight, strength, density moisture content, and other characteristics are also different. The ability of wood to resist loads depends on including the type, direction, and duration of loading; ambient conditions of moisture content and temperature. The strength properties of wood are of importance in structural design. They are measure of the ability of wood to resist which tends to alter its shape, size or result in any other deformation. Mechanical properties determine the applicability of wood in structure as well as many other uses where resistance to bending, compression, tension, shear and other effect required.
In Myanmar, more than 100 wood species are available to the prospective user. Efficient use of our nation's timber resource is a vital concern. Markets must be developed for lesser known timber species. The use of lesser known timber species is equally appropriate in civil and structural applications. The utilization of lesser used timber species in Myanmar will solve the crisis of demand and supply of timber.
The objective of this experimental study is to investigate the strength properties of timbers selected from four lesser used seasoned timber species in Myanmar.

II. EXPERIMENTAL PROGRAMME A. Materials
In this study, four lesser used seasoned timber species are selected. They are Inn, Kanyin, Thit Yemane.

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Experimental Study on Properties of Some Lesser Used Seasoned g, Yangon Technology University and humidity. Related to its physical properties, wood has different colors and odors. In addition, its unit weight, strength, density moisture content, and other characteristics are also different. The ability of wood a number of factors, including the type, direction, and duration of loading; ambient conditions of moisture content and temperature. The strength properties of wood are of importance in structural design. They are measure of the ability of wood to resist externally applied force which tends to alter its shape, size or result in any other deformation. Mechanical properties determine the applicability of wood in structure as well as many other uses where resistance to bending, compression, other effect of external force is In Myanmar, more than 100 wood species are available to the prospective user. Efficient use of our nation's timber resource is a vital concern. Markets must be developed for lesser known timber species. of lesser known timber species is equally appropriate in civil and structural applications. The utilization of lesser used timber species in Myanmar of demand and supply of timber.  Compressive strength parallel to grain test In this test, the compressive strength is measured by applying the force parallel to the grain, as shown in Figure 3.

Tensile strength perpendicular to grain test
Tensile strength perpendicular to the grain is a measure of the resistance of wood to forces acting across the grain which then to cause splits or cleavage, as shown in Figure 5.

Shear parallel to grain test
This test is the measure of the total load required to shear the specimen in two. The shear strength is the ability to resist internal slipping of one part upon another along the grain or across the grain. Figure. 6 represents shear test.

III. TEST RESULTS AND DISCUSSIONS
In this study, the strength properties which are commonly used in design purposes are measured including bending, compression parallel and perpendicular to the grain, tension perpendicular to the grain, and shear parallel to the grain for four species. For each test and species 30 specimens were measured at 12%MC, according to ASTM D 143-09. Figure 7 and 8 represent the fibre stress in bending, modulus of rupture and modulus of elasticity, respectively. The compressive stresses parallel and perpendicular to grain were as shown in Figure.9 and 10, respectively. Figure.11 and 12 represent the tension and shear strength parallel to grain, respectively.  Table 2. The allowable strength of each property is obtained by multiplying the respective factor of safety given in Table 3 to the mean strength shown in Table 2. It is listed in Table 5 and as shown in Figure 13,14 and 15 respectively. The allowable density of each species is listed in Table 4.

IV. CONCLUSIONS
Based on results of this study, it can be concluded that: 1. The unit weight of lesser used seasoned timber species is different from one species to another. It can be observed that as the density increases, the various strength properties also increase. 2. For the density, Kanyin has greatest and Yemane has lowest. 3. Inn has greatest value and Yemane has lowest value for bending strength, compressive strength perpendicular to grain, and tensile strength parallel to grain. 4. In compressive strength parallel to grain, Thit-Sein has greatest and Yemane has lowest. 5. In shear strength, Kanyin has the highest and Yemane has the lowest.
6. Yemane has the lowest strength for all tests and therefore it should not be used among these four lesser used seasoned species. 7. Although Thit-Sein has the high strength for almost all tests, chemical treatment should be added to this species for usage due to its nature of likely to be attacked by insets.

V. ACKNOWLEDGEMENTS
The author is deeply grateful her student Pan Ei Phyu for her support and effort to writing this paper.