EFFECT OF DENSITY ON ULTRASONIC VELOCITY IN WOOD

The effect of density on the ultrasonic velocity in wood, and the corr elation between the ultrasonic velocity in tangential, radial, and lon gitudinal directions were examined on seven softwoods and 12 hardwoods . Ultrasonic velocity in the tangential and radial directions increase d with increased density on the whole, but when balsa (Ochroma pyramid ale) and lignum-vitae (Guaiacum sanctum) eliminated, the ultrasonic ve locities were independent of densities. Although ultrasonic velocity i n the longitudinal direction was independent of density on the whole, it could be classified into three groups. In these three cases, the re lationships between ultrasonic velocity, Young's modulus, and density are discussed. On the correlation between ultrasonic velocities in the longitudinal, radial, and tangential directions, ultrasonic velocity in the radial direction tended to increase with that in the tangential direction, and there was no relationship between ultrasonic velocitie s in the longitudinal and radial directions. Ultrasonic velocity in th e longitudinal direction was independent of that in the tangential dir ection on the whole, and it could be divided into two groups. The rati os of longitudinal to tangential directions (V-L/V-T) and of radial to tangential directions (V-R/V-T) in ultrasonic velocities tended to de crease with increased density.