Preliminary study on quality assessment of Eucalyptus spp.by ultrasonic method

摘要

In this paper, measurements have been made for determining ultrasonic velocity along the multiple transverse direction of eucalyptus disc for assessing defect (hollowness) at their centre. Measurements have also been made for determining ultrasonic velocity along the longitudinal direction of samples by using ultrasonic transmission technique, subsequently strength properties (modulus of elasticity and modulus of rupture) of these samples determined under static bending test as per conventional testprocedure. The results indicate that ultrasonic velocity along multiple transverse directions decreases in a particular path that is passes through the centre in round timber due to the presence of defects. The results also reveal that drop (%) of ultrasonic velocity increases with increasing magnitude of defect size in timber. Regression equation of ultrasonic velocity (V) with each modulus of elasticity (MOE) & modulus of rupture (MoR) and between (MoR) & (MoE) are fitted of the type: y = A x +B, where: A & B are constants. The results indicate^ that ultrasonic velocity increases with increasing modulus of elasticity as well as with increasing modulus of rupture in timber within the study range of moisture content. A linear relationship between modulus of rupture and modulus of elasticity have also been fitted (co-relatipn coeff.= 0.708). These finding may be useful for the quality assessment of timber at the inspection site by nondestructive test way.