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九大粕屋演習林産の23年生および43年生スギ（Cryptomeria japonica）ならびに同北海道演習林産の20年生および30年生カラマツ（Larix leptolepis）造林木の樹幹各部位からだら挽きで製材した．それらを所要の寸法に木取ってプレーナ仕上げし，断面3．5cmX5．Ocmまたは3．2cmX5．Ocm，長さ3．2mの生状態での実大寸法の小割材について，その長幅面負荷（Flatw...ise Loading）および短幅面負荷（Edgewise Loading）における材長方向にわたる曲げ弾性係数（MOE）分布を，測定間隔10cmの部分スパン中央たわみ測定法で求めた．さらに，MOEに直接関与する力学的指標としての欠点断面二次モーメント率（ROI）（又木ら，1987）の材長方向分布を求めた．そして，それらのMOEとRO王の材長方向分布の標準偏差（SD_E，SD_I）および変動係数（CV_E, CV_I）を求め，さらには各小割材の材長方向の両分布についてχ^2（カイ平方）分布を基にした巨視的ならびに微視的対応度の検定を行って，各種条件下における小割材のMOE変動について解析した．その結果を要約するとつぎの通りである．（1）スギならびにカラマツ生材状態の各小割材において，MOEとROIの材長方向分布の対応は，全長対応では，統計的に有意なものがわずかしか認められないが，大きく集中した欠点部を局部的にもつ小割材ではその部分での局部対応の有意なものが多く存在する．（2）スギと同様にカラマツにおいても，樹高方向の根元寄りの部位（1番玉丸太）からの小割材は低いMOEを示し，樹幹半径方向の中央部（髄側）からの材ではMOEは低く平坦に分布するが，外周部（樹皮側）からの材ではMOEは高くて変動のはげしい分布をとる．（3）スギ，カラマツとも，MOEとROIの両材長方向分布の変動量（SD_EとSD_I, CV_EとCV_I）の関係は，一概に中央部材では小さく狭い範囲に分散するが，外周部材では広い領域に分散する．
Small lumbers of 3.2m long and 3.2cm by 5.0cm or 3.5cm by 5.0cm in cross section were prepared from various positions of 23-year-old Sugi (Cryptomeria japonica), and 20- and 30-year-old Karamatsu (Larix leptolepis) stenms, which were grown in the Kasuya Forest and the Hokkaido Forest of Kyushu University, respectively. Within each measuring span along the length of the piece of green lumber, the localized modulus of elasticity (MOE) and the ratio of cross-sectional moment of inertia of defect to that of entire section (ROI) were measured by the same methods as shown in the previous paper (MATAKI et al., 1987). The standard deviations, SD_E and SD_t, and the coefficients of variation, CV_E and CV_t were calculated for MOE and ROI, respectively. Throughout the length of the piece of lumber, the correspondence of distribution of MOE to that of ROI were furthermore determined by the statistical analysis. The following results were obtained ; (1) For most of small lumbers from Sugi and Karamatsu stems, the correspondences of the whole distribution of MOE to that of ROI were obscure, however, the partial correspondences were significant at the part of large or concentrated defect. (2) The MOE varied slightly at a low level throughout the length for lumbers from the pith side of stem, while it varied violently at a high level for lumbers from the bark side of Karamatsu stem as well as Sugi stem. (3) The relationships between SD_E, and SD_t, and between CV_E and CV_t were extensively dispersed for lumbers from the bark side, while the relationships were relatively limited for lumbers from the pith side of both Sugi and Karamatsu stems.続きを見る
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