APPLICATION OF STRESS WAVES TO ESTIMATE MOISTURE CONTENT IN Eucalyptus WOOD

Abstract

Accurate monitoring of moisture content in Eucalyptus wood during the drying process is critical to improving product quality. And as electric meters lose accuracy in some moisture ranges, in this work a Stress Wave Timer was used to try and assess the possibility of estimating wood moisture based on variation in the propagation velocity of stress waves in two Eucalyptus species. Effects of knot area and board basic density on the propagation of stress waves were also analyzed, using analysis of variance and observing mean values for these characteristics. Equations were fitted and wood moisture content could be estimated by the stress wave propagation method using nonlinear models or a multiple linear model, with wave propagation velocity, basic density and knot area being used as independent variables. Best fits were obtained for boards showing no visible defects (knots, cracks etc.). The propagation velocity of stress waves through the wood was found to vary as a function of the knot area, wood density and anatomical orientation (visual analysis) of the boards. Knots had a stronger influence on wave transmission when they were present in radially cut boards.