An equipment test for grading lumber by transverse vibration technique.

Marcelo Rodrigo Carreira, Marcela Candian

Abstract


Due to the great variability of its mechanical properties, the rational use of lumber for structural purposes is directly conditioned to its grading. There are several techniques available for grading structural lumber. The most relevant one is the transverse vibration technique which obtained reliable results in non-destructive evaluation of lumber. The purpose of this work is to present the bases for the mechanical grading of lumber and the results of the calibration test of the frst transverse vibration equipment developed in Brazil. In this research 30 beams of cupiúba (Goupia glabra) with nominal dimensions of 5 cm X 10 cm X 300 cm, were used. The tests were accomplished at the Wood and Timber Structures Laboratory (LaMEM) of the University of São Paulo (USP). The results showed a strong correlation between the elasticity modulus measured by the static bending test and the one obtained with the transverse vibration equipment, showing the high reliability of the vibration method for the grading of structural lumber. A determination coeffcient (R²) of 0.896 was obtained with the Brazilian equipment, showing that it can be used in the grading of lumber.


Keywords


Lumber; Timber structures; Grading; Non-destructive evaluation; Transverse vibration.



DOI: http://dx.doi.org/10.5433/1679-0375.2008v29n1p3

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