Journal of the Korean Wood Science and Technology

The Korean Society of Wood Science & Technology (한국목재공학회)
권호 표지

Investigation of Radial Distributions of Tangential Strains and of Moisture Contents within a Log Cross Section by Circumferential Slices

  • Choi, Jun-Ho (Department of Wood Science & Technology, (Institute of Agriculturial Sci. & Tech.) Chonbuk National University) ;
  • Lee, Nam-Ho (Department of Wood Science & Technology, (Institute of Agriculturial Sci. & Tech.) Chonbuk National University)
  • Received : 2007.07.23
  • Accepted : 2007.12.12
  • Published : 2008.03.25
Download PDF
⟨ Previous Next ⟩

Abstract

This study was carried out to provide the so-called circumferential slicing method for investigating radial distributions of the tangential strains and of moisture contents within the log cross section (LC) of Kalopanax pictus during indoor drying it. While the heartwood showed an almost uniform moisture content distribution in the range of about 50~55% in case of the green wood, it has gradually decreased toward the outer side, showing about 19% of moisture content difference from the innermost slice. Although the moisture gradient along the radial direction has gradually become gentle as drying progresses, the sapwood of the outer side represented the moisture contents below the fiber saturation point after 24 hours of drying while the heartwood in the inner part showed the moisture contents higher than the fiber saturation point. The pith side was laid under the tensile stress after 24 hours of drying, and then gradually decreasing toward the bark side, and showed the distribution being switched again to the tensile stress on the bark side. As the drying has progressed, this trend got more intensified, and finally showed the U-shaped distribution model after 48 hours of drying. The circumferential slice test is considered to be suitable in quantitatively determining the tangential strains and moisture content within a LC.

Keywords

References

  1. Brandao, A. and P. Perre. 1996. The "Flying Wood"-A quick test to characterise the drying behavior of tropical woods. Proceedings of the 5th International IUFRO Wood Drying Conference. Quebec city, Canada: 315-324.
  2. Choi, J. H. and N. H. Lee. 2004. Effect of end-taping and removal of sapwood on radial distribution of moisture content and tangential strains during radio-frequency/vacuum drying of Cedrela sinsensis log cross sections. J. of Wood Science 50(3): 209-216
  3. Jung, H. S. et al. 2000. Special Wood Drying. Seoul National University Press: p. 173-175 (in Korean).
  4. Kang, W., N. H. Lee, and J. H. Choi. 2001. A radial distribution of moistures and tangential strains within a larch log cross section during radio-frequency/vacuum drying. Proceedings of the 7th International IUFRO Wood Drying Conference 2001. Tsukuba, Japan: 376-381.
  5. Kang, W., N. H., Lee, and J. H. Choi. 2004. A radial distribution of moistures and tangential strains within a larch log cross section during radio-frequency/vacuum drying. Holz als Roh und Werkstoff 62(1): 59-63 https://doi.org/10.1007/s00107-003-0432-3
  6. Kubler, H. 1973a. Role of moisture in hygrothermal recovery of wood. Forest Prod. J. 5(3): 198-204.
  7. Kubler, H. 1973b. Hygrothermal recovery under stress and release of inelastic strain. Forest Prod. J. 6(1): 78-85.
  8. Kubler, H. 1975. Study on drying of tree cross sections. Wood Sci. 7(3): 173-181.
  9. Kubler, H. 1977. Formation of checks in tree stems during heating. Forest Prod. J. 27(1): 41-46.
  10. Lee, N. H. and K. Hayashi. 2000. Effect of end-covering and low pressure steam explosion treatment on drying rate and checking during radio-frequency/vacuum drying of Japanese cedar log cross sections. Forest Prod. J. 50(2): 73-78.
  11. Lee, N. H., K. Hayashi, and H. S. Jung. 1998. Effect of radio-frequency/vacuum drying and mechanical press-drying on shrinkage and checking of walnut log cross sections. Forest Prod. J. 48(5): 73-79.
  12. Lee, N. H., C. Y. Li, and J. H. Choi. 2003. Determination of trend a radial distribution of moisture content within a log cross section by of domestic hardwoods -. J. of the Wood Sci. and Tech. 31(1): 10-15 (in Korean)
  13. Lee, N. H., C. Y. Li, and J. H. Choi. 2004. Comparison of moisture distribution along radial direction in a log cross section of heartwood and mixed sapwood and heartwood during radio-frequency/vacuum drying. J. of Wood Science 50(6): 484-489
  14. Lee, N. H., C. Y. Li, J. H. Choi, U. D. Hwang, and Y. M. Jin. 2004. Determination of trend of a radial distribution of moisture content within a log cross section by oven-drying of circumferential slices (II) -for some of domestic softwoods-. J. of the Wood Sci. and Tech. 32(2): 19-25 (in Korean)
  15. Shupe, T. F., E.T. Choong, and M. D. Gibson. 1995a. Differences in moisture content and shrinkage between outerwood, middlewood, and corewood of two yellow-poplar trees. Forest Prod. J. 45(9): 85-90.
  16. Shupe, T. F., E. T. Choong, and M. D. Gibson. 1995b. Differences in moisture content and shrinkage between innerwood and outerwood of a single cottonwood tree. Forest Prod. J. 45(10): 89-92.
  17. Wilhelmy, V and H. Kubler. 1973. Stresses and checks in log ends from relieved growth stresses. Wood Sci. 6(2): 136-142.