Relationship among the dynamic and static elastic properties of air-dry Eucalyptus delegatensis R.!Baker

Nondestructive impact-induced resonance vibrations and spectral analysis were used to determine the relationships among dynamic longitudinal elastic modulus (E-L), wave velocity (V-L) in the fibre direction, dynamic flexural elastic modulus (E-F), logarithmic decrement (LD) in air-dry specimens of Eucalyptus delegatensis R. Baker, measuring 20 x 20 mm transversely and 300 mm long. The dynamic properties were compared with the static elastic modulus (MOE) and the modulus of rupture (MOR) obtained from three point bending tests. E-L was very highly related to EF, MOE, MOR and air-dry density, whereas the relationship between V-L and static moduli was highly significant, but less strong. V-L was related positively to air-dry density, and negatively to static shear modulus (Longitudinal-Tangential and Longitudinal-Radial planes). EF was the single best predictor of both MOE and MOR. LD was negatively related to MOE and MOR, The association between the dynamic (G(F)) and static (G(ST)) shear modulus values was only moderately good. The mean dynamic modulus was 3.4 times greater than the mean static value. E-L may be used to estimate the true Young's modulus in specimens in which shear contributes significantly to bending.