Elastic constants of particleboard with ultrasonic technique

Ultrasonic technique was used for the mechanical characterization of two types of commercial particleboards. The elastic constants were calculated in the hypothesis of orthotropic symmetry. The specimens were prepared in parallel (direction 1) and perpendicular (direction 2) versus the technological direction of the board production and 45° in planes 12, 13 and 23 (where direction 3 is thickness). All of the nine terms of the stiffness matrix were calculated with ultrasonic wave velocity method using longitudinal and shear waves. The corresponding technical constants (Young's modulus, shear modulus and Poisson's ratios) were calculated from the stiffness matrix. For the Young's modulus, comparison was made with conventional four point bending test. Negative Poisson's ratios were calculated from ultrasonic data. The anisotropy of particleboard was determined with ultrasonic velocities data.