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Title: Machine Grading of High-Density Hardwoods (Southern Blue Gum) from Tensile Testing
Authors: Martins, Carlos 
Moltini, Gonzalo
Dias, Alfredo M. P. G. 
Baño, Vanesa
Keywords: dynamic modulus of elasticity; EN 14081-2; Eucalyptus globulus Labill.; indicating property; mechanical properties; non-destructive testing; strength class combinations; tensile strength
Issue Date: 2023
Publisher: MDPI
Project: UIDB/04029/2020 
Associate Laboratory Advanced Production and Intelligent Systems ARISE under the reference LA/P/0112/2020 
Institute for Business Competitiveness of Castilla and Leon, co-financed by FEDER funds, through the project CCTT2/18/SO/0001: Research for the modernisation of manufacturing processes and timber grading to obtain technological products. 
EUFORE project (No. 101081788), funded by the European Union through the Horizon Europe program 
Serial title, monograph or event: Forests
Volume: 14
Issue: 8
Abstract: Hardwoods commonly have high mechanical properties, which makes them interesting for structural use, but softwoods dominate the structural timber market in Europe. Tensile strength classes are recommended for engineered wood products. However, current European standards do not provide tensile strength classes for hardwoods and the declaration of tensile properties from machine grading in the industry is not yet possible. The present paper aims to contribute to the revision of European standards through the technical group CEN/TC124/WG2/TG2: Tensile strength classes for hardwoods, of the European Standardisation Committee. An experimental campaign which involved machine grading and tensile testing of over 569 boards of Southern blue gum (Eucalyptus globulus Labill.) from Spain and Portugal was made. Six new tensile strength classes were defined, from ET24 (ft,0,k = 24 N/mm2, Et,0,m = 18 kN/mm2 and rk = 590 kg/m3) to ET42 (ft,0,k = 42 N/mm2, Et,0,m = 23 kN/mm2 and rk = 640 kg/m3). Machine grading made possible the definition of six strength class combinations. Four combinations resulted in 40% of the sample being assigned to the higher strength class, with low percentages of rejection (varying between 1% and 14%). This demonstrates the high mechanical properties of the species and the performance improvement of machine grading with respect to current visual grading.
ISSN: 1999-4907
DOI: 10.3390/f14081623
Rights: openAccess
Appears in Collections:FCTUC Eng.Civil - Artigos em Revistas Internacionais
I&D ISISE - Artigos em Revistas Internacionais

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