A New Three Dimensional Model for the Prediction of Ultrasonic Velocity in Orthotropic Wood Materials

This paper deals with a three-dimensional model capable of determining the propagation velocities of ultrasonic waves in wood material to predict its elasticity properties characterized by a cylindrical orthotropy. The model is based on the two-dimensional Hankinson's model proposed already used for the velocity characterization in each plane of orthotropy. The three-dimensional allows the consideration of the cylindrical orthotropy by correcting the ultrasonic wave propagation velocity crossing a line connecting transmitter and receiver according to its orientation and its projection in the main orthotropy reference frame which, locally, takes a spherical coordinate system form characterized by its latitude and its longitude . To determine these coordinates in the material, whose main directions are subject to the direction of the fibers and the growth rings, a finite element support allows the recalculation of the propagation velocities whatever the orientation of the propagation line. Finally, this work proposes an experimental validation and a determination process of the model parameters thru an inverse analysis algorithm.