Experimentally it was observed that the dynamic modulus of elasticity calculated from the velocity of stress wave or ultrasonic wave and the density of wood in green condition increased with increasing moisture content. This statement disagrees with the physical meaning of data observed with static tests, namely the decreasing of all mechanical properties of wood with increasing moisture content. To elucidate this discrepancy a simulation procedure was developed to study the effect of free water, present in wood above the fiber saturation point on wave velocity. For this purpose the coefficient k, related to the mobility of free water was defined, as a ratio of free water vibrating simultaneously with water present in cellular wall (k = 0.6 for stress wave velocity and k = 0.7 for ultrasonic velocity). The simulation procedure using corrected values of velocity and density showed that the elastic moduli are relatively constant above the FSP, as all the mechanical parameters determined with static tests.
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