Effect of Compressive Load on Shrinkage of Larch Blocks During Radio-Frequency Vacuum Heating


  • Chengyuan Li
  • Nam-Ho Lee


Loading direction, tangential shrinkage, radial shrinkage


This study was carried out to investigate the effect of a compressive load of 0.092 MPa on the shrinkage of the larch blocks with sides of 40 mm each, when subjected to vacuum combined with radio-frequency heating.

The shrinkages in the loading direction were significantly increased; for example, the tangential shrinkages of the blocks loaded compressively on their radial surfaces (loaded-RS), and the radial shrinkages of the blocks loaded compressively on their tangential surfaces (loaded-TS) were approximately one and one-half times as much as those for the load-free blocks.

The shrinkages perpendicular to the loading direction were restrained, for example, the radial shrinkage for the loaded-RS, and the tangential shrinkage for the loaded-TS.


Armstrong, L. D. 1972. Deformation of wood in compression during moisture movement. Wood Sci.5(2): 81-85.nBarber, N. F. 1968. A theoretical model of shrinking wood. Holzforschung22(4):97-103.nBoyd, J. D. 1974. Anisotropic shrinkage of wood: Identification of the dominant determinants. Mokuzai Gakkaishi20(10):473-482.nHarris, R. A., And M. A. Taras. 1984. Comparison of moisture content distribution, stress distribution, and shrinkage of red oak lumber dried by a radio-frequency/vacuum drying process and conventional kiln. Forest Prod. J.34(1):44-54.nHoffmeyer, P. 1993. Non-linear creep caused by slip plane formation. Wood Sci. Technol.27(5):326-327.nHoffmeyer, P., And R. W. Davidson. 1989. Mechano-sorptive creep mechanism of wood in compression and bending. Wood Sci. Technol.23(3):217-225.nLee, N.-H., And K. Hayashi. 2000. Effect of end-covering and low pressure steam explosion treatment on drying rate and checking during ratio-frequency/vacuum drying of Japanese cedar log cross sections. Forest Prod. J.50(2):73-78.nLee, N.-H., And H. S. Jung. 2000. Comparison of shrinkage, checking, and absorbed energy in impact bending of Korean ash squares dried by a radio-frequency/vacuum process and a conventional kiln. Forest Prod. J.50(2): 69-72.nLiu, F., S. Avramidis, And R. L. Zwick. 1994. Drying thick western hemlock in a laboratory radio-frequency/vacuum dryer with constant and variable electrode voltage. Forest Prod. J.44(6):71-75.nPang, S. 2002. Predicting anisotropic shrinkage of softwood, part 1. Theories. Wood Sci. Techol.36(1):75-91.nPentoney, R. E. 1953. Mechanisms affecting tangential and radial shrinkage. J. For. Prod. Res. Soc.32(1):27-32.nQuirk, J. T. 1984. Shrinkage and related properties of Douglas-fir cell walls. Wood Fiber Sci.16(1):115-133.nShin, H. Y. 2001. Study on the wood quality variation within larch stem. Page 190 in Proc. Korean Society of Wood Science and Technology, 2001 fall meeting, Gyeongju, Korea.nSkaar, C. 1972. Water in wood. Syracuse, New York, NY. 132 pp.nTaniquchi, Y., And S. Nishio. 1991. High frequency power-vacuum drying of wood. IV. Comparison of physical and mechanical properties of lumber dried by several drying methods. J. Japan Wood. Res. Soc.37(5):405-414.nTrebula, P., P. Joscak, And I. Klementl. 1993. The influence of vacuum drying on some physical properties of beech and oak wood. Pages 151-160 in Proc. Vacuum Drying of Wood'93, Zvolen, Slovakia.nUgolev, B. N. 1992. Wood deformability and drying stresses. Page 14 in Proc. 3rd IUFRO Drying Conference, Vienna, Austria.nWu, Q., And M. R. Milota. 1994. Effect of creep and mechano-sortive effect on stress development during drying. Drying Technology12(8):2059-2063.nWu, Q., And M. R. Milota. 1995. Rheological behavior of Douglas-fir perpendicular to the gain at elevated temperatures. Wood Fiber Sci.27(3):285-295.n






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