Detection of pith location in chestnut lumber (Castanea sativa Mill.) by means of acoustic tomography and longitudinal stress-wave velocity

Abstract

The objective of this paper was to detect pith location in chestnut lumber by using acoustic tomography techniques. To this end, the velocity gradient was analysed by relating the value of longitudinal stress-wave velocity to the distance from the point where velocity was measured to the pith. A commercial stress-wave timer was used to measure longitudinal stress-wave velocity in 100 × 200 × 400 mm3 pieces of chestnut lumber (Castanea sativa Mill.) obtained from mature trees. The analysed pieces were conditioned to 20% moisture content. Results were classified according to the distance from the point at which velocity was measured to the pith. ANOVA revealed significant differences for mean velocity between the values obtained nearest the pith (at less than 40.0 mm) and the values obtained farthest from the pith. Velocity increased with distance to pith. The coefficient of determination for the linear regression between both variables was R2=0.96. The results of the tests showed a statistically significant relationship between longitudinal velocity and distance to pith. Such results allowed for the estimation of pith location in the area with the lowest velocity values.