Browsing by Author "Brunetti, Michele"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Investigating the potential of strength grading green Eucalyptus grandis lumber using multi-sensor technology
    (North Carolina State University, 2017-11) Nocetti, Michela; Proller, Marco; Brunetti, Michele; Dowse, George P.; Wessels, C. Brand
    The exploitation of Eucalyptus grandis lumber as structural material may take advantage of the finger-joint and edge-gluing of the boards while they are still wet, so as to reduce the natural susceptibility of the species to warp and split during drying. But the strength grading needed for structural uses, usually performed on dried lumber, should be done before any gluing process, then already in wet condition. Thus, detection and assessment of selected properties of the wet lumber were evaluated. Eucalyptus grandis boards were measured by a multi-sensor machine soon after sawing, then dried and measured again. Destructive bending tests were then performed to determine the mechanical properties of the lumber and several predictive models were compared. The determination on non-destructive parameters by the machine was as effective on fresh as on dry lumber. The dynamic modulus of elasticity was the best single predictor of mechanical properties. In contrast, the know parameter did not show a correlation between strength and stiffness robust enough to justify the efforts to measure it. Wet grading proved to be as effective as dry grading. Therefore, the study suggests that measuring only dynamic modulus of elasticity on fresh lumber is the best approach for the mechanical grading in Eucalyptus grandis.
  • Thumbnail Image
    Item
    Mechanical and physical properties of Cunninghamia lanceolata wood decayed by brown rot
    (Italian Society of Silviculture and Forest Ecology, 2019-04-03) Li, Shengcai; Gao, Yuewen; Brunetti, Michele; Macchioni, Nicola; Nocetti, Michela; Palanti, Sabrina
    ENGLISH ABSTRACT: The relationship between the mechanical properties of Cunninghamia lanceolata (Chinese fir) wood and the development of fungal decay was investigated with the aim of implementing a statistical model useful as a non-destructive and a fast method for determining the state of conservation of in-service timber structures. Artificial decay due to brown rot fungi was induced on wood specimens and physical and mechanical test were performed periodically, as well as anatomical observation of wood, FT-IR spectroscopic and XRD diffraction analysis. As a result, Chinese fir was confirmed to have a good durability against fungi, showing a mass loss percentage of 7.21% on average after 14 weeks of exposure. On the contrary, the mechanical properties reduced dramatically during the decay test: a 19% decrease was observed for compression strength and 21% for tensile strength. The mechanism of decay was explored and the corresponding damage constitutive model was proposed.
  • Thumbnail Image
    Item
    Mixed visual and machine grading to select Eucalyptus grandis poles into high-strength classes
    (MDPI, 2021) Brunetti, Michele; Aminti, Giovanni; Wessels, C. Brand; Nocetti, Michela
    ENGLISH ABSTRACT: Before round timber can be profitably used in construction, it needs structural characterization. The visual grading of Eucalyptus grandis poles was integrated with additional parameters developed by multivariate regression analysis. Acoustic velocity and dynamic modulus of elasticity were combined with density and pole diameter in the estimation of bending strength and stiffness. The best models achieved were used to group the visually graded material into qualitative structural classes. Overall, dynamic modulus of elasticity was the best single predictor; and adding density and diameter to the model improved the estimation of strength but not of stiffness. The developed parameters separated the material into two classes with very distinct mechanical properties. The models including velocity as a parameter did not perform as well. The strength grading of Eucalyptus grandis poles can be effectively improved by combining visual parameters and nondestructive measurements. The determination of the dynamic modulus of elasticity as a grading parameter should be preferred over that of acoustic velocity