Prediction of Compression Properties in Three Orthotropic Directions for Some Important Turkish Wood Species Using Ultrasound

Compression properties in three orthotropic directions for some important Turkish wood species, including Calabrian pine (Pinus brutia Ten.), Taurus cedar (Cedrus libani), Oriental beech (Fagus orientalis), and sessile oak (Quercus petraea), were studied using non-destructive and destructive techniques. The materials used in the study consisted of 720 small clear specimens of nominal dimensions of 20 x 20 x 60 mm. The influence of equilibrium moisture content (EMC) was studied over four batches of 15 specimens each, conditioned for six to eight weeks before testing at a temperature of 20 ± 2 °C and at four different relative humidity conditions (50%, 65%, 85%, and 95%). Time of flight values were measured with a commercial ultrasonic tester. Using the time results from the ultrasound device, the wave velocities (length/time) and Edyn values were calculated. Samples were also tested in uniaxial compression to determine the Young’s modulus and compression strength values in three orthotropic directions. The Edyn correlated well with the Young’s modulus and compression strength of the specimens; coefficients of determination ranged between 0.75 and 0.96. Moisture content seems to have more influence than density on sound velocities. Results showed that there is a weak and mostly negative correlation between the density of the specimens and the sound velocity values