Influence of initial stress and varnish coatings on vibration damping in wooden beams

The paper concerns the problem of initial stress and varnish coatings influence on vibration damping in wooden beams. The effect of initial stress on damping properties of the sprucewood- and beechwood-beams has been experimentally investigated. The relationship between logarithmic decrement versus compressive stress and tensile stress distribution along the beam's axis has been determined. Also, the influence of different varnish brands on damping properties of sprucewood-, great maple wood- and pinewood-beams has been established.