Development of measuring Young's modulus of planting stock
1997
Nakamura, N. (Tokyo Univ. (Japan). Faculty of Agriculture)
Young's modulus and strength are important indexes in the use of timber as structural material. Young's modulus has a positive correlation to strength and can be measured nondestructively. The breeding and growing of trees with a large Young's modulus would be an important way to encourage the future use of domestic timbers as structural members in glue-laminated lumber or trusses. The objective in this research was to determine whether the value for Young's modulus measured in planting stock would reflect the value for this characteristic in older trees. Specifically, would it be possible to select for this variable on the basis of the value for Young's modulus in planting stock? A procedure to measure Young's modulus in planting stock was developed. Planting stock were dug out of the nursery bed. The stem of the seedling was set at two points and a load was applied at the center of the span. Young's modulus for the planting stock was calculated from the deflection produced from the load. Two trends were observed. Firstly, planting stock that had a larger value for Young's modulus initially, also had a larger value after two years. Secondly, planting stock with poor growth, i.e. lower tree e/height and smaller diameter, had a larger Young's modulus
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