Zy. Cai et al., NEW TECHNIQUE FOR EVALUATING DAMPING OF LONGITUDINAL FREE-VIBRATION IN WOOD-BASED MATERIALS, Journal of testing and evaluation, 25(4), 1997, pp. 456-460
Classical log-decrement techniques have been used to evaluate the damp
ing property of materials. However, the consistency and repeatability
of the methods when applied to wood and wood-based materials have been
found lacking. A different way to view the free vibration of a single
-degree-of-freedom system in the x - (x) over dot plane is presented.
A new method that uses all sample points and does not require a knowle
dge of the initial conditions to determine the damping properties is d
eveloped. A comparison between the new method and the classical method
is made for three wood-based materials: solid wood, medium density fi
berboard (MDF), and particleboard. The results show that the new metho
d is more consistent and repeatable in measuring damping than the clas
sical method. For the six cases examined, there was an absolute averag
e difference of 3.8% in measuring log-decrement between the methods.