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The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus >
No.23 (1976/12) >

Title :沖縄産スギ材の材質(第 4 報) : 強度的性質(林学科)
Title alternative :Studies on the Quality of Sugi wood (Cryptomeria japonica D. Don) grown in Okinawa. IV. : Mechanical properties (Department of Forestry)
Authors :仲宗根, 平男
小田, 一幸
Authors alternative :Nakasone, Hirao
Oda, Kazuyuki
Issue Date :1-Dec-1976
Abstract :沖縄産スギ材の強度的性質を明らかにするために, 地スギ, 実生スギを対象に, 縦圧縮試験と曲げ試験を行った。1.圧縮強さおよび曲げ破壊係数は地スギ, 実生スギとも樹令の増加とともに, 髄から10年輪目前後まで増加し, その後はほぼ安定する。このことは, 仮道管長が10年輪目あたりから安定することと一致したので, 10年輪前後までを未成熟材, それ以降を成熟材とすることができる。2.圧縮強さを圧縮ヤング率で除した値, および破壊係数を曲げヤング率で除した値は, 地スギ, 実生スギとも他県産スギ材より大きいので, 沖縄産スギ材の特徴であろうと考えられる。また, 未成熟材と成熟材では, 未成熟材の方がこれらの値が大きい。したがって, 未成熟材はヤング率のわりに強度が大きいといえる。3.地スギと実生スギとでは, 地スギの比重が高いこともあって, 強度およびヤング率は地スギの方がすぐれているが, 比強度, 比ヤング率は両者に大差が認められない。4.地スギ, 実生スギとも, 圧縮強さおよび曲げ破壊係数は比重依存性が高いが, 圧縮ヤング率および曲げヤング率は比重依存性が低い。
Compression tests parallel to grain and bending tests were carried out to examine the mechanical properties of Ji-sugi (Okinawan indigenus Sugi propagated by cuttings) and introduced Seedling-sugi grown in Okinawa. 1) Compressive strength and modulus of rupture of both Ji-sugi and introduced Seedlingsugi increased with tree age until about 10th annual ring from pith, and afterwards, these were apporoximately constant as shown in Fig. 1 and 2. As this result agrees with that obtained by measurement of tracheid length which becomes constant from 10th annual ring, it can be considered that juvenile wood zone of these Sugi is from pith to 10th annual ring and adult wood zone is from 10th annual ring to cambium. 2) From the results of compressive and bending tests, we observed considerable differences between these Sugi grown in Okinawa and those grown on other prefectures on σc/Ec and σb/Eb. That is, the values of σc/Ec and σb/Eb of Ji-sugi and introduced Seedlingsugi were higher than those of other Sugi. Furthermore, we found that though there was no differences in these values between Ji-sugi and introduced Seedling-sugi, these values of juvenile wood of these Sugi were higher than those of adult wood as shown in Table 2 and 3. 3) On Ji-sugi and introduced Seedling-sugi, specific gravity showed high correlation to compressive strength and modulus of rupture, but it showed low correlation to Young's modulus in compression and bending.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/4311
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.23 p.365 -373
Appears in Collections:No.23 (1976/12)

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