Influence of back-cut placement on internal stress in the first stage of felling

• UEMURA Takumi

  For. and Forest Prod. Res. Inst.

• OKAYASU Takashi

  Dep. of Bioproduction Environ. Sci., Kyushu Univ.

• KASHIMA Jun

  For. and Forest Prod. Res. Inst.

• SASAKI Tatsuya

  For. and Forest Prod. Res. Inst.

• OKA Masaru

  For. and Forest Prod. Res. Inst.

• KARIYA Yoshihiro

  For. Training Inst. For. Mech. Ctr.

• INOUE Eiji

  Dep. of Bioproduction Environ. Sci., Kyushu Univ.

Bibliographic Information

Other Title

• 倒伏初期における追口高さが内部応力に与える影響
• トウフク ショキ ニ オケル オイクチ タカサ ガ ナイブ オウリョク ニ アタエル エイキョウ

Abstract

To evaluate an experimental felling tree method scientifically, the influence of back-cut placement on internal stress around hinges was examined. Observations of the felling process revealed that the corners of back-cut began to crack at the initial stage. Then, the relationship between back-cut placement and the direction of cracking was investigated, and the internal stress of trees until cracking occurred was analyzed by finite element method (FEM). The tree model was regarded as isotropic material, and the loading condition was set so that the amount of horizontal displacement at 1m in height would reach 3cm. High stress was induced at one of the two corners placed on the end of a back-cut which seemed to be the starting point of cracking caused by large displacement. The direction of the first cracking was related to the placement of the back-cut, namely, it moved upward when the back-cut was lower than the notched corner, and moved downward when the back-cut was higher. Cracking that moves upward is not desirable because it not only reduces the commercial value of logs but also poses risks for loggers. A more precise analysis in which the simulated form of the notched corner more closely resembled an actual felling method showed the possibility that cracking would move upward even when the back-cut was placed at the same height as the notched corner. This suggests that the back-cut should be made a little higher than the notched corner to prevent cracks from moving upward. The results of FEM analysis and observations of cracking directions confirmed that methods used for teaching about felling in Japan are practical.

Journal

• Journal of The Japan Forest Engineering Society

  Journal of The Japan Forest Engineering Society 24 (1), 11-18, 2009

  The Japan Forest Engineering Society

Keywords

• felling method
• internal stress
• back-cut placement
• hinge
• FEM

Details

• CRID: 1390282679442309760
• NII Article ID: 110007227821
• NII Book ID: AN10531146
• DOI: 10.18945/jjfes.kj00005581728
• ISSN: 21896658
• ISSN: 13423134
• NDL BIB ID: 10316328
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I10316328
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • CiNii Articles
• Abstract License Flag: Disallowed