Estimating variations in wood density by drilling resistance
2006
Yamashita, K.(Forestry and Forest Products Research Inst., Tsukuba, Ibaraki (Japan)) | Nagao, H. | Kato, H. | Ido, H.
To investigate the possibility of estimating the wood density from drilling resistance, drilling resistance data obtained by resistograph(R) were compared with wood density on small clear specimens of 27 hardwood species (air-dried density:256-995kg/m3) and Sugi (air-dried density:314-476kg/m3). There were significant relationships between the drilling resistance averages and the wood densities both in the green wood and in the air-dried wood, and equations for estimating wood density from drilling resistance were derived. To investigate the possibility of estimating the density variation inside logs or structural members, the density estimated from the equations were compared with the density measured by soft X-ray densitometry on diametrical Sugi samples. In the green wood, the drilling resistance and the estimated densities increased with drilling depth much more than did the measured density variation, suggesting that it would be difficult to accurately estimate the density variation inside living trees and green logs. In the air-dried wood, however, the estimated density showed the same variation as the measured density, indicating that it could be possible to estimate the wood density variation. It would be possible to relatively compare the density variation patterns among rings, while estimating the density values of early wood and late wood separately would be difficult.
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