Eighth International Conference on Advances in Civil, Structural and Mechanical Engineering CSM
Author(s) : Ezeagu C.A, Onwunduba S.J
This work analyzed the plastic and elastic properties of some Nigerian timber as a structural material. Charpy impact test method was used to determine the impact energy/toughness of twenty locally available timber species, comprising of ten hardwoods and ten softwoods. Three sets of specimen (having dimension 125 mm by 12.5 mm by 12.5 mm)were obtained from each of the timber species.The first set had grain angle parallel to the longitudinal axis of the specimen, the second set had grain perpendicular to the longitudinal axis of the specimen and the third had grain at an angle of 45 degree to the longitudinal axis of the specimen. The toughness energies of the materials were observed to vary as the angle of the grain varied. The toughness energies of the materials were observed to vary as the angle of the grain varied, with the maximum strength obtained when the grain orientation was parallel to the axis of the tree trunk. The toughness energy obtained for the different softwood species was 1.49Kgfm/cm2 for Obia, 2.89Kgfm/cm2 for Okwe, 1.08Kgfm/cm2 for Avu, 2.2Kgfm/cm2 for Akpu, 2.4Kgfm/cm2 for Anyasualo, 2.26Kgfm/cm2 for Egba, 1.6Kgfm/cm2 for Owen, 1.23Kgfm/cm2 for Ojoo, 1.08Kgfm/cm2 for Yellow man, 1.4Kgfm/cm2 for Marima. While for the hardwood specimen, the following range of result was obtained; 2.22Kgfm/cm2 for UghiMmanu, 2.4Kgfm/cm2 for Ukpi, 2.62Kgfm/cm2 for UburuMmiri, 1.85Kgfm/cm2 for Iroko, 1.08Kgfm/cm2 for Oha,1.6Kgfm/cm2 for Mango nkiti, 1.42Kgfm/cm2 for Egbu, 1.46Kgfm/cm2 for Meligna, 2.0Kgfm/cm2 for Obala and 1.6Kgfm/cm21 for Mahogany. A comparison of the toughness energy of the twenty timber specimen was made, which showed that Cordiamillenii (Okwe) possessed the highest impact energy/toughness which occurred when the grain orientation was parallel to the longitudinal axis of the specimen. Further comparison of the results with that of established steel showed a 59.3% drop in the toughness energy of Cordiamillenii with respect to that of an established X100 steel.