Damping Factor of Pinus Silvestris Timbers in Longitudinal, Transverse and torsional free vibrations

The effect of vibration kind and direction on damping properties of wood has been studied, taking into account the specimen width in rectangular wooden beams of Silvestre Pine wood (Pinus silvestris). 39 sound and clear beams with the dimensions of 36*4.5*2 cm (LRT) (wide specimens) made from Silvestre pine wood were tested and damping factor of the first mode was determined through logarithmic decrement method in temporal field separately for longitudinal, flexural and torsional free vibration tests. Then the specimens were cut to smaller specimens of 36*2*2 cm (LRT) (thin specimens) and then were tested in the same way as the initial wider specimens. There was no effect damping of factor on width variation while different vibration directions significantly affected this property. The greatest damping size was of torsional and the smallest of longitudinal vibration test. There was no difference between LR and LT flexural damping factors. It has been predicted that in all vibration directions, every dimension of the specimens (e.g. in-situ) could be used to evaluate the damping factor of a proper piece of wood.