Summary
Tangential shrinkage was measured on longitudinal-tangential slices of separate earlywood and latewood from one board of Eucalyptus regnans F.Muell. at various temperatures. Large amounts of collapse shrinkage were measured in the latewood slices, and lesser amounts in the earlywood slices. Collapse shrinkage in the earlywood was found only when the slices were dried at temperatures above a minimum temperature (the “collapse threshold temperature”). End-coated board sections approximately 200 mm long were rapidly dried at dry-bulb temperatures below the collapse threshold temperature for earlywood. Incipient internal checks were found in the latewood of these boards. Board sections dried at higher temperatures showed internal checks starting in both early and latewood. A non-linear drying simulation model was modified to take the heterogeneous nature of wood into account. This model predicted that internal checks would form in this wood even if it were dried sufficiently slowly to avoid surface checking.
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Abbreviations
- D:
-
Diffusion coefficient
- ec :
-
Creep strain
- ei :
-
Instantaneous strain
- em :
-
Mechano-sorptive strain
- en :
-
Net strain
- eu :
-
Unconfined shrinkage strain
- EW:
-
Earlywood
- FSP:
-
Fibre saturation point
- LW:
-
Latewood
- L-T:
-
Longitudinal-tangential slice
- MC:
-
Moisture content (kg water/kg dry wood)
- q:
-
Moisture concentration
- R-T:
-
Radial-tangential slice
- t:
-
Time
- y:
-
Depth in board
References
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The author is pleased to acknowledge the assistance of Emeritus Professor A. R. Oliver, Associate Professor P. E. Doe, University of Tasmania, and the Australian Furniture Research and Development Institute
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Innes, T.C. Collapse and internal checking in the latewood of Eucalyptus regnans F.Muell. Wood Sci.Technol. 30, 373–383 (1996). https://doi.org/10.1007/BF00244434
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DOI: https://doi.org/10.1007/BF00244434