ULTRASONIC TECHNIQUE FOR DETERMINING THE EXTENT OF FUNGUS ATTACK OF BEECH AND PINE WOOD

Decaying of beech (Fagus sylvatica L.) and pine (Pinus sylvestris L.) wood by white-rot and brown-rot (Coriolus versicolor and Gloeophyllum trabeum) was estimated by an ultrasonic velocity measurement technique. The ultrasonic technique detects the degrading of the wood from the earliest stages. Due to the fungus attack the decrease in the velocities of the longitudinal waves along the radial and tangential orthotropic axes is greater than the weight loss of the specimen. The computation of acoustic invariants from the measurements of the velocities of longitudinal and transversal waves can be used to determine the location of the modification of wood anisotropic behaviour induced by different types of fungus.