THE USE OF ULTRASONIC METHOD FOR ESTIMATING WOOD ELASTIC CONSTANTS

Abstract

The objective of this work was to estimate wood elastic constants, applying utrasonic non destructive tests. Wood from: Fava Amargosa (Vataireopsis speciosa), Jequitiba Rosa (Cariniana micrantha), Peroba d'Agua (Rauwolfia paraensis) e Peroba Mico (Aspidosperma macrocarpum) was used. The main wood elastic constants were estimated by means of the determination of the velocities of ultrassonic propagation, based on the equation : V² =Ei / p ; were: V – wave propagation velocity; Ei – modulus of the wood elasticity in relation to the axis (longitudinal, radial or tangential ); p – volumetric mass. Mean values obtained for ultrasonic velocity in the three wood perpendicular directions (longitudinal, radial or tangential) showed always a statiscally significant difference for the species studied, at 1% level of probability (F test). These differences in the ultrassonic waves propagation, in relation to the wood axe, are explained by the anatomic structure of the material. The ultra sonic non-destructive methodology showed to be an alternative for studying wood mechanical properties, mainly on the elastic constants determination.