International Journal of Farm Sciences 5(3) : 119-123, 2015 Studies on tensile strength property of commercial timber species of Solan district, Himachal Pradesh SEEMA BHATT, BUPENDER DUTT, RAJESH KUMAR MEENA and TASRUF AHMAD* Department of Forest Products and Utilization Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan 173230 HP, India *Forest Research Institute, Dehradun 248006 Uttarakhand, India Email for correspondence: seema_chail@yahoo.co.in ABSTRACT Investigations were carried out to study the tensile strength of some timber species commercially used in Solan market. Five timber species namely teak (Tectona grandis), Sal (Shorea robusta), dark red (Shorea sp), light red (Shorea sp) and yellow (Shorea sp) were tested for tensile strength. The test results revealed that teak and Sal showed the best performance in tension. Overall the indigenous Sal showed the maximum strength and light red was found to be the most vulnerable. Keywords: Timber; trees; tensile strength, stress INTRODUCTION Timber is the oldest natural resource and the diverse ways in which it has been fashioned over the centuries tell the story of civilization better than any other material. Timber has always held a significant place in the human economy. It has served man a structural material for his buildings, furnishings, tools, weapons etc and until recently as only readily available fuelwood. It remains a dominant and versatile raw material especially in construction, refurbishment, furniture packaging and temporary works (Bowyer et al 2003). The reason of being most popular engineering material for timber is its versatile properties like strength and durability comparing to other materials in similar approach. The properties of timber vary widely not only between species but also between pieces of the same species (Lavers 1969). In case of durability it is the property of timber to remain in sound condition for a long time when exposed to the forces of nature in an exposed or underground condition (Aziz 1995).
Bhatt et al In Solan market timber has versatile uses and plays a vital role in construction purposes. Throughout the market besides softwood timbers viz pine, Kail, deodar etc timbers are used for internal domestic works such as in making doors, windows, furniture, cabinet etc. is a trade name for group of species of Shorea in Malaysia, Sarawak, Brunei and Indonesia and corresponds to Seraya in north Borneo and Lauan in the Philippines. Shoreas of the Indian origin commonly known as Sal have been grouped under Balau group from Malay Peninsula. The genus consists of a large number of species belonging to family Dipterocarpaceae and is one of the most important sources of timber in southeast Asia. In India Sal wood being much sought after for construction purposes its demand is much more than its supply. Therefore wood is imported in bulk. All the wood imported to India is well suited to construction purposes and furniture particularly for interior framing as a cheaper alternative to Sal. Keeping in view the commercial importance of the species for construction purpose this study was aimed to investigate tensile strength and durability of some commercial timber species. MATERIAL and METHODS The species of timber were selected on the basis of the availability in the local markets and obviously the priority was given to the species which were being used significantly at various levels of its practice and having economic importance for commercial purposes. The selected species were teak (Tectona grandis), Sal (Shorea robusta), dark red (Shorea sp) light red (Shorea sp) and yellow (Shorea sp). The mechanical property studied was tensile strength using a Universal Testing Machine (100 KN). After physical measurements had been taken and recorded the specimen was placed in the grips and securely clamped with special care taken to have the longitudinal axis of the specimen and the grip coinciding so that the tensile forces were axial and generally uniformly distributed throughout the cross sections without flexure along its length. The load was applied at a constant rate for that maximum load was achieved until wood sample was broken and the load shown on the computer graph had dropped. For each species the tensile test of the 12 specimens was carried out. The tensile properties of the specimen were tested and the average values were reported. The specimens size used was 300 mm 10 mm 10 mm with 12 per cent moisture content. RESULTS and DISCUSSION The mean values of the tensile strength property as determined in air-dry conditions are presented in Table1 (Fig 1, Plate 1 and 2) along with the corresponding values for standard teak, Tectona grandis 120
Tensile strength of timber Table 1. Variation in ultimate stress in different species Species Ultimate stress (KN/mm 2 ) Sal 0.0781 Dark red 0.0641 Light red 0.0297 Yellow red 0.0414 Teak 0.1235 Mean 0.0908 CD 0.05 0.0053 SEm 0.0025 0.14 0.12 Ultimate stress 0.1 0.08 0.06 0.04 0.02 0 Sal Dark red Light Red Yellow Red Teak. Fig 1. Variation in ultimate stress in different species for the purpose of comparison. The maximum tensile strength was recorded in T grandis followed by Shorea robusta and minimum in light red followed by yellow. When the specimens failed in tension the line of the failure was observed to be zigzag type along the depth of the specimens. Similar type of results were obtained by Saravanan et al ( 2014) in Melia dubia with T grandis at different age gradation. Ahmad et al (2005) also reported same results in tropical hardwoods and Hossain et al (2012) in different trees species namely teak or Shegun (T grandis), Sal (S robusta), Sil Korai (Albizia procera), rain tree (Samanea saman), 121
Bhatt et al Plate 1. Samples before testing Plate 2. Samples after testing 122
Tensile strength of timber Jam (Syzygium sp), jackfruit or Kanthal (Artocarpus heterophylus) and mango (Mangifera indica). REFERENCES Ahmad Z, Bon YC and Abd Wahab ES 2005. Tensile strength properties of tropical hardwoods in structural size testing. International Journal of Basic and Applied Sciences 10(3): 1-6. Aziz MA 1995. A text book of engineering materials. Revised edn, Trans-World Book Company, Dhaka, Bangladesh. Bowyer JL, Shmulsky R and Haygreen J 2003. Forest products and wood science- an introduction. 4 th edn, Iowa State Press, Iowa, United States. Hossain MB and Abdul Awal ASM 2012.Mechanical properties and durability of some selected timber species. Malaysian Journal of Civil Engineering 24(1): 67-84. Lavers GM 1969. The strength properties of timbers. Forest Products Research, Bulletin # 50. Ministry of Technology, UK. Saravanan V, Parthiban KT, Thiruneraiselvan S, Kumar P, Vennila S and Kanna US 2014. Comparative study of wood physical and mechanical properties of Melia dubia with Tectona grandis at different age gradation. Research Journal of Recent Sciences 3: 256-263. Received: 24.2.2015 Accepted: 15.5.2015 123