Publicación: HYGROMECHANICAL STRAINS DURING THE DRYING OF EUCALYPTUS NITENS BOARDS
Fecha
2016
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MADERAS: CIENCIA Y TECNOLOGIA
Resumen
COLLAPSE AND DRYING STRESSES ARE CURRENTLY INDUCED DURING THE DRYING OF EUCALYPTUS NITENS IN
SOLID WOOD PRODUCTS. THE PURPOSE OF THIS STUDY WAS TO INVESTIGATE THESE DRYING STRESSES BY MEASURING
HYGROMECHANICAL STRAINS DURING THE DRYING OF EUCALYPTUS NITENS BOARDS.
SMALL SAMPLES OF EUCALYPTUS NITENS WOOD WERE ORIENTED IN THE RADIAL AND TANGENTIAL DIRECTIONS AND
TESTED TO DETERMINE THE HYGROMECHANICAL STRAINS DURING THE DRYING PROCESS. THIS EXPERIMENTAL WORK
CONSISTED OF CANTILEVERED BENDING TESTS CONDUCTED UNDER VARIABLE RELATIVE HUMIDITY CONDITIONS. TESTS
WERE PERFORMED IN A CONDITIONING CHAMBER AT 30 °C WITH AN EQUILIBRIUM MOISTURE CONTENT RANGING
FROM 22 TO 12% UNDER FOUR LEVELS OF STRESS: 0, 10, 20 AND 30% OF THE RUPTURE LOAD. THE STRAINS WERE
DETERMINED USING STRAIN GAUGES, AND THE TOTAL DEFLECTION WAS MEASURED WITH A LINEAR VARIABLE DIFFERENTIAL
TRANSFORMER.
THE RESULTS SHOW THAT IN HYGROMECHANICAL STRAINS DURING THE DRYING OF EUCALYPTUS NITENS, BOTH
THE SURFACE DEFORMATION AND MECHANO-SORPTION STRAIN WERE FOUND TO BE PROPORTIONAL TO THE APPLIED
STRESS AND REACHED THEIR MAXIMUM VALUES IN THE TANGENTIAL DIRECTION. THE TOTAL DEFLECTION INCREASED
0,18 MM/MM WITH A SURFACE DEFORMATION OF 0,20 MM/MM, AND THE MECHANO-SORPTIVE STRAIN PROVIDES A
GREATER CONTRIBUTION WITH A VALUE OF 0,11 MM/MM, THUS CORRESPONDING TO 59% OF THE TOTAL DEFORMATION.
IN ATTEMPTS TO IMPROVE THE DRYING SCHEDULES OF EUCALYPTUS NITENS TO DEVELOP SOLID WOOD PRODUCTS,
MECHANO-SORPTIVE BEHAVIOR MAY BE APPLIED TO RELIEVE COLLAPSE AND DRYING STRESS.
Descripción
Palabras clave
Wood drying, Mechano-sorption, Drying stresses, Deformation, Deflection
