Damping Properties of Selected Tropical Wood Species from Cameroon Forest Assessed Via Free Transverse Vibration Method

Abstract

Despite the diverse use of wood in industrial construction, some technological properties of tropical wood species are still little known. This concerns more particularly the logarithmic decrement, viscous damping ratio, loss factor, quality factor and specific damping ratio, which were little studied and documented in the literature, which hinders the reliable design of structures under dynamic solicitation. This study describes a non-destructive method for determining the damping properties of wood. It was based on the analysis of the attenuation of the free transverse vibrations of a fixed support-free specimen following excitation. Cameroonian forests abound with important species that were much in demand for structural applications and were often subjected to dynamic loads. However, in the literature and in the available databases, very little information was available on the vibration properties of these wood species. To solve this problem, three specimens of twenty-four wood species with a cross-section of 10 mm × 20 mm, with a length of 1600 mm, were prepared and subjected to a free vibration test in the fixed support-free configuration. The accelerations as a function of time were obtained. Displacement data were derived from recorded accelerations, and the logarithmic decrement was calculated using the first twenty-one amplitude peaks. Using known relationships between parameters, the viscous damping ratio, loss factor, quality factor and specific damping ratio were deduced. The results obtained were relatively variable between species. Among the studied wood species, Azobé exhibited the highest damping ratio, while Wengé showed the lowest. Compared with the data available in the literature for the same species, there was a considerable difference.