Ultrasonic determination of the elastic and shear modulus on aged wood

The wood elastic constants are of great importance in the design of structural elements. In particular, the elastic modulus in the longitudinal direction is often used for strength estimation and grading of wood. Ultrasonic techniques are commonly applied to determine elastic parameters in laboratory experiments and for condition assessment of existing wooden structures. In the present study, the elastic parameters (elastic modulus and shear modulus) for aged and un-aged Mexican pine (Pinus strobus) wood were measured by the ultrasonic emission-transmission technique. The experimental measurements were carried out using longitudinal and shear ultrasonic transducers with a central frequency of 1 MHz and 0.5 MHz respectively. Ultrasonic data and scanning electron microscopy (SEM) were performed, establishing a direct correlation with the measurements of the longitudinal and shear ultrasonic velocities and the elastic properties developed on the naturally aged and un-aged wood. Finally, the elastic and shear modulus of the wood before and after aging conditions were determinate. Therefore, the obtained experimental results not only contribute to the existing knowledge about aged wood but provide useful information about the possibilities of re-using wood as well.