Abstract: The aim of this study was to know the variation profile of the specific energy consumption required to cut woods with varying densities and moisture contents. Therefore, peripheral cuts were performed in the longitudinal direction of the grain with numerical control controlled by Computational Numerical Command in woods of different densities, established at different drying stages. An energy analyzer, capable of calculate the specific energy consumed during the wood processing, was used to measure the energy information. The results indicated that the higher the wood density, the greater the positive influence of the moisture content on the specific cutting energy. In the anhydrous condition, the higher the wood density, the higher the cutting energy. With increased moisture content, less cutting power was required during the wood processing. Therefore, it was possible to conclude that during the milling type mechanical processing of wood, moisture content has a great influence on the specific cutting energy consumption.

ABSTRACT Proposing technological innovations in the investigation of the structure and behaviour of wood is important to optimize its use. The assimilation of methods diffused in other areas, such as particle image velocimetry (PIV), can allow a rich range of information for different aspects. The aim of this study was to estimate the Young’s modulus using the PIV technique, independently of the wood density. The Young modulus value was obtained by universal testing machine, transversal vibration and PIV technique. Cedrela spp. and Eucalyptus cloeziana wood specimens were analyzed and their Young modulus were compared and correlated. The PIV technique presented mean Young’s modulus values statistically equal to those of the universal testing machine. The standard error of prediction from PIV approach was 0.46 and 0.97 GPa for Young’s modulus estimates for Cedrela spp. and Eucalyptus cloeziana wood, respectively.

Abstract The effect of planting density on the anatomical characteristics of wood is still matter of debate. The aim of the study was to investigate the influence of planting density on the variation of wood anatomical elements in Eucalyptus and Acacia trees cultivated in areas of high planting density (monospecific) and low planting density (mixed) stands. The fiber length, fiber width, fiber lumen diameter, cell wall thickness, vessel diameter and vessel frequency were evaluated. The measurements were made from wood discs taken from five Eucalyptus urophylla x E. grandis trees and five Acacia mangium trees grown in high planting density (monospecific plantations, 1667 trees/ha) and in low planting density (mixed stands, 500 trees/ha), totalizing 20 trees at 4.5 years old. Eucalyptus and Acacia produced wood with shorter fibers and smaller vessels in high density stands, when compared to its equivalent in low density. Acacia presented more frequent vessels and fibers with walls thicker than its equivalent in low planting density. Eucalyptus presented longer and thinner fibers and vessels more frequent than Acacia, regardless of planting density. On the other hand, in high planting density, Acacia presented fibers with walls thicker than Eucalyptus and in low density of planting their vessels were larger.

Resumen El efecto de la densidad de plantación sobre las características anatómicas de la madera aún es tema de debate. El objetivo de este estudio fue investigar la influencia de la densidad de plantación sobre la variación de elementos anatómicos de la madera de árboles de Eucalyptus y Acacia, creciendo en áreas de alta densidad de plantación (monoespecífica) y en rodales de baja densidad de plantación (mixta). Se evaluaron: longitud, ancho y diámetro de lumen de la fibra, grosor de pared celular, diámetro y frecuencia de vasos. Las mediciones se hicieron en rodajas de madera tomadas de cinco árboles de Eucalyptus urophylla x E. grandis y cinco de Acacia mangium, creciendo en alta densidad de plantación (plantaciones monoespecíficas, 1667 árb/ha) y de otro tanto igual de árboles creciendo en baja densidad de plantación (rodales mixtos, 500 árb/ha), lo que hace un total de 20 árboles de 4.5 años de edad. Eucalyptus y Acacia de rodales de alta densidad produjeron madera con fibras más cortas y vasos más pequeños en comparación con sus equivalentes en baja densidad de plantación. Eucalyptus presentó fibras más largas y delgadas y vasos más frecuentes que Acacia, independientemente de la densidad de plantación. Acacia presentó vasos más frecuentes y fibras con paredes más gruesas que su equivalente en plantación de baja densidad. Por otro lado, en alta densidad de plantación, Acacia presentó fibras con paredes más gruesas que Eucalyptus y en baja densidad de plantación sus vasos fueron mayores.