Variation of tensile strength with annual rings for lumber from the Japanese larch [Larix leptolepis]

To examine the effectiveness of long rotation forestry and the potential of complete utilization of Japanese larch (Larix kaempferi Carriere), we designed a tensile test using the lumber from six 87-year-old sample trees. Results showed that strength properties of lumber varied greatly in the radial...

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Bibliographic Details
Published in:Journal of wood science 2000-08, Vol.46 (4), p.284-288
Main Authors: Zhu, J. (Gifu Univ. (Japan)), Nakano, T, Tokumoto, M, Takeda, T
Format: Article
Language:English
Subjects:
FELLING CYCLE
Forestry
GROWTH RINGS
Knots
LARIX LEPTOLEPIS
MECHANICAL PROPERTIES
Storage modulus
STRENGTH
Tensile strength
Tensile tests
Trees
WOOD PROPERTIES
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Summary:To examine the effectiveness of long rotation forestry and the potential of complete utilization of Japanese larch (Larix kaempferi Carriere), we designed a tensile test using the lumber from six 87-year-old sample trees. Results showed that strength properties of lumber varied greatly in the radial direction within trees, but all sample trees showed a similar trend. There was little difference in dynamic Young's modulus but a large difference in tensile strength (TS) between the lumber and small clear specimens from undestroyed parts of the lumber. These differences decreased with an increase in ring number and became constant after 30 years. The presence and distribution of knots markedly affected the TS; and among the knot indices, the knot number (Kn) and knot area ratio of a maximum single knot (Km) proved to be effective for explaining the effect of knots. The distribution of Kn and Km in the radial direction agreed with the variation of TS in the radial direction. By investigating the variation patterns of lumber and small clear specimens in the radial direction, it was found that the strength properties of both required a long time, about 30 years, to reach a relatively constant state.
ISSN:1435-0211
1611-4663
DOI:10.1007/BF00766218