Abstract
This paper analyzes the usability of different dynamic moduli of elasticity and wood density for the prediction of mechanical properties – static modulus of elasticity and modulus of rupture – in samples with grain deflection from the longitudinal direction. Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis) with different grain characteristics were used for this purpose. The fiber deflection was caused by the presence of interlocked grain or the working process. The three nondestructive techniques used in this study – longitudinal and flexural resonance method and ultrasound method – provided higher values of modulus of elasticity than the static bending test, but close correlation was observed between these variables. The weakest correlation was found for the ultrasound method which is probably caused by its measuring mechanism. The prediction of the modulus of rupture is less accurate when the dynamic modulus of elasticity is compared with the static modulus of elasticity; on the other hand, it was still good in comparison with the density model, which is inapplicable when grain deflection occurs in wood. In the wood of Zebrano where the interlocked grain was strongly developed, almost all of the correlation coefficients showed the lowest values and the prediction of modulus of rupture by nondestructive techniques was unsatisfactory.
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Claims 8
Claim · model-written summary
The nondestructive techniques gave higher modulus of elasticity values than the static bending test in tropical hardwoods.
Verbatim
e0“Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis)”
e1“provided higher values of modulus of elasticity than the static bending test, but close correlation was observed between these variables”
Claim · model-written summary
The nondestructive techniques showed close correlation with the static bending test in tropical hardwoods.
Verbatim
e0“Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis)”
e1“provided higher values of modulus of elasticity than the static bending test, but close correlation was observed between these variables”
Claim · model-written summary
The ultrasound method gave the weakest correlation among the nondestructive techniques, probably because of its measuring mechanism.
Verbatim
e0“Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis)”
e2“longitudinal and flexural resonance method and ultrasound method”
e3“The weakest correlation was found for the ultrasound method which is probably caused by its measuring mechanism”
Claim · model-written summary
Predicting modulus of rupture from the dynamic modulus of elasticity is less accurate than from the static modulus of elasticity in tropical hardwoods.
Verbatim
e0“Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis)”
e4“The prediction of the modulus of rupture is less accurate when the dynamic modulus of elasticity is compared with the static modulus of elasticity”
Claim · model-written summary
Predicting modulus of rupture from dynamic moduli was still good in comparison with the density model in tropical hardwoods.
Verbatim
e0“Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis)”
e4“The prediction of the modulus of rupture is less accurate when the dynamic modulus of elasticity is compared with the static modulus of elasticity”
e5“it was still good in comparison with the density model, which is inapplicable when grain deflection occurs in wood”
Claim · model-written summary
The density model is inapplicable when grain deflection occurs in wood.
Verbatim
e0“Five tropical hardwoods (Afzelia bipindensis, Intsia bijuga, Millettia laurentii, Astronium graveolens and Microberlinia brazzavillensis)”
e5“it was still good in comparison with the density model, which is inapplicable when grain deflection occurs in wood”
Claim · model-written summary
In Zebrano wood with strongly developed interlocked grain, almost all correlation coefficients were the lowest.
Verbatim
e6“In the wood of Zebrano where the interlocked grain was strongly developed, almost all of the correlation coefficients showed the lowest values”
Claim · model-written summary
In Zebrano wood, prediction of modulus of rupture by nondestructive techniques was unsatisfactory.
Verbatim
e6“In the wood of Zebrano where the interlocked grain was strongly developed, almost all of the correlation coefficients showed the lowest values”
e7“the prediction of modulus of rupture by nondestructive techniques was unsatisfactory”