Zusammenhang zwischen Schallgeschwindigkeit und morphologischen, physikalischen und mechanischen Eigenschaften von Holz

Summary

The sound velocity of pine, fir, beech, limba and oboto was determined according to the sonic vibration method with a frequency of 0,1 MHz. Their dependence from the density differs with the species. The density of springwood and summer-wood, fibre length and sound direction influence the rate of the velocity of sound. The value measured apparently corresponds to the velocity in the most sound-permeable zone of the wood. Calculations of the mean dynamic modulus of elasticity are, therefore, not possible. The test values show that the dynamic moduli of elasticity by 10 to 34% exceed the static ones measured. However, the procedure ist suited for the determination of the moduli of elasticity of springwood and summerwood. A satisfactory correlation between sound velocity and strength properties was not be proved. The wood moisture content influences the velocity of sound also beyond fibre saturation. With gamma-radiated wood, inspite remarkably reduced strength, no change in the sound velocity was to be observed. Branches have little influence on the sound velocity, but cause remarkable damping of the sound impulse.