Relationship between anatomy and vibration behaviour of softwoods and hardwoods

Abstract

The influence of cell type and cell arrangement on the vibration characteristics of 91 softwood and hardwood species was studied under controlled conditions. The vibration of standardized wood plates was measured by means of high-resolution laser sensors with an accuracy of ± 0.02 μm and a sampling frequency of 30 kHz. First and second order waves within the vibration spectra were identified by Fast Fourier Transformation analysis. The amplitudes, the frequencies, and the duration of the waves of the 91 timber species were compared by means of principal component analysis. Special attention was paid to the influence of tracheids, vessels, storied rays, growth rings, and the anatomical direction of the wood on the vibration spectra. Due to significant differences in vibration between samples on which the vibration was induced in the transverse, radial, and tangential plane, a comparison between tree species was only possible if plates with precise and identical orientation of the grain were used. In plates with exactly oriented surfaces along the radial plane, distinct vibration characteristics were found in timber species with tracheids as ground tissue (softwoods), in timbers without distinct growth rings, and in timbers with storied rays. In contrast, no relationship was found between the arrangement of the vessels, the width of the xylem rays and the vibration characteristics of hardwoods.