Effect of physical and anatomical parameters on the micro drilling resistance of Eucalyptus wood
Name: DAIANA SOUZA DE JESUS
Publication date: 27/02/2019
Examining board:
Name |
Role |
|---|---|
| PEDRO GUTEMBERG DE ALCÂNTARA SEGUNDINHO | Internal Examiner * |
| REJANE COSTA ALVES | External Examiner * |
Summary: The non-destructive evaluation methods of wood quality have great benefits because they are fast, low-cost procedures that allow the analysis of wood in different forms (sawing, logging or standing). Among the various non-destructive testing techniques, the Resistograph has stood out by allowing a rapid evaluation of the strength, density and other properties of the wood. The moisture of the wood can have a significant impact on the resistance to drilling and should be considered when guaranteeing the efficiency of the apparatus in the prediction of wood properties. The objective of this work was to evaluate the influence of moisture content, apparent density and wood anatomy on the drilling resistance. Twelve clones of the 6-year-old Eucalyptus grandis x Eucalyptus urophylla hybrid were studied. Five trees were collected per clone, totaling 60 trees, from which were discs that were drilled and analyzed in different moisture conditions. It was observed a slight decrease in the amplitude between the perforated woods in the anhydrous condition and in the hygroscopic equilibrium content, but there was no statistical difference, WHEREas in the moisture from the saturated fiber point an increase was observed as a function of the increase of the moisture in the wood to full saturation condition. The correlation between drilling resistance perforation amplitude and basic density was r= 0.65 in the anhydrous condition, r= 0.74 in the hygroscopic equilibrium content, r= 0.50 in the fiber saturation point (FSP) and not significant in the saturated wood, so the best moisture content to predict wood density would be those below the FSP. For the fiber anatomy, a moderate correlation was observed between the amplitude and the wall thickness (r= 0.60). The diameter of the lume, therefore, presented negative correlation (r= -0.38) and the fiber length with r= 0.43.
Keywords: Resistograph, non-destructive evaluation of wood, moisture content, apparent density, wood anatomy.
