Ultrasonic method for estimation of modulus of elasticity of <i>Eucalyptus grandis</i> wood

Abstract

This study aimed to verify the relation between the modulus of elasticity of Eucalyptus grandis W. Hill ex Maiden wood obtained from destructive testing of static bending and from non-destructive testing by ultrasound, both after thermal rectification. A total of 85 samples, with dimensions of 2.5 x 2.5 x 41.0 cm (thickness, width and length), were made from eucalyptus planks. These samples, as well as those without thermal rectification (control), were subjected to two heat treatments, called Combination and Kiln, and then evaluated. In the combination treatment, the wood was subjected to thermal treatment in an autoclave at 130 ± 3 °C and a pressure of 0.2 MPa for 3 h and, after a conditioning period, to heat in a kiln at 160 ± 1 °C for the same length of time, whereas the other treatment consisted of only thermal rectification in a kiln. The main results showed a moderate relation between destructive and non-destructive methods, with the best results recorded in the samples without thermal rectification. With the continuous improvement of the non-destructive techniques, the ultrasound is confirmed as a viable method to obtain values of the modulus of elasticity as a function of the dynamic modulus of elasticity.