Comparison between three-point and four-point flexural tests to determine wood strength of Eucalyptus specimens



Document title: Comparison between three-point and four-point flexural tests to determine wood strength of Eucalyptus specimens
Journal: Maderas : ciencia y tecnología
Database:
System number: 000544800
ISSN: 0718-221X
Authors: 1
2
Institutions: 1Universidade Federal de Lavras, Departamento de Ciências Florestais, Lavras, Minas Gerais. Brasil
2Univ Montpellier, CIRAD, Montpellier. Francia
Year:
Season: Jul
Volumen: 20
Number: 3
Pages: 333-342
Country: Chile
Language: Inglés
English abstract Comparison between flexural wood strength values obtained from three-point and four-point bending tests in wood were only reported in few previous works, but remains unclear. Thus, the aim of this study was to determine the relationship between wood strength (MOR) obtained by 4-point and 3-point bending tests in Eucalyptus. Two or three specimens were cut from the same scantling (thus considered as twin) and submitted to flexural vibration tests. Then 190 wood specimens were tested by 4-point bending tests and 138 twin specimens were submitted to 3-point bending tests. Wood strength determined from 3-point bending test presented significantly higher mean value (76,8 MPa) than that from 4-point bending test (73 MPa). A linear regression for converting MOR from 3-point to 4-point bending test was proposed for these Eucalyptus specimens: MOR4p = 0,889 × MOR3p + 5,14 in MPa (R²=0,74). The correlation of MOR in 3-point bending with density was higher (R²=0,57) than in 4-point bending (R²=0,45). The correlations between dynamic elastic moduli and moduli of rupture were similar (circa R²=0,57 for MOR3p and R²=0,65 for MOR4p).
Keyword: Acoustic vibration,
Density,
Eucalyptus grandis,
Static bending test,
Stiffness,
Strength
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