Nondestructive evaluation of dynamic properties in beach wood using free vibration method on free- free bar

In this study effect of different NDT methods on dynamic properties in beech wood (flexural vibration and longitudinal vibration method) were evaluated. 29 clear samples with nominal dimension of 2×4×36 cm selected and bending vibration in free-free beams and longitudinal vibration tests was performed on them. Results shows strong correlation between dynamic Young''s modulus and acoustic coefficient measured with both Longitudinal vibration and flexural vibration method. Measuring damping factor values was significantly higher in flexural vibration compared to longitudinal vibration method، While the acoustic converting efficiency values from flexural vibration was smaller than values of this factor in longitudinal vibration method. There was good correlation between dynamic shear modulus of elasticity from flexural vibrations and dynamic modulus of elasticity in both methods، that it provides possibility of estimate the shear modulus of elasticity values according to dynamic Young''s modulus of elasticity values from longitudinal vibration test. The results also indicated was a good correlation between the phase velocity in first to third modes from the bending vibration. In addition there was good correlation between sound velocity from longitudinal vibration and the phase velocity in first to third modes from the bending vibration.