Characterizing Microscopic Behavior of Wood Under Transverse Compression. Part II. Effect of Species and Loading Direction
Keywords:
Radial compression, tangential compression, cellular structure, cell-wall collapse, stress-strain responseAbstract
Specimens of four species with different cellular structures (white spruce, jack pine, white ash, and aspen) were tested in radial compression. Deformation characteristics were observed and measured using a microscope at different magnifications. The magnified images were recorded with a video recorder, which were then played back for deformation measurements. Stress-strain responses of these specimens were determined from the measured load and deformation. As expected, the softwood and hardwood responses to radial compression were influenced by the anatomical features. Tangential compression tests were also conducted on white spruce and jack pine specimens. It was found that the mechanisms of deformation in radial and in tangential compression were distinctly different for these softwood species. In radial compression, cell-wall deformation dominated elastic behavior, and collapse of the weakest cells in earlywood coincided with the onset of yielding observed in the stress-strain curve. Cell collapse developed only in earlywood, while latewood cells mainly underwent elastic deformation. In tangential compression, elastic deformation was dominated by the bending of the latewood layers. For the two hardwood species, the measured elastic strain under radial compression was dominated by deformations in the vessels. Yield point on stress-strain curves was related to the collapse of these vessels.References
Bodig, J. 1965. The effect of anatomy on the initial stress-strain relationship in transverse compression. Forest. Prod. J.15(5):197-202.nBodig, J., and B. A. Jayne. 1982. The mechanics of wood and wood composites. Van Nostrand Reinhold Co. Inc., New York. NY.nDinwoodie, J. M. 1965. The relationship between fibre morphology and paper properties. Tappi J.48(8):440-447.nEasterling, K. E., R. Harryson, L. J. Gibson, and M. F. Ashby. 1982. On the mechanics of balsa and other woods. Proc. R. Soc. Lond. A383:31-41.nGibson, L. J., and M. F. Ashby. 1982. The mechanics of two-dimensional cellular materials. Proc. R. Soc. Lond. A382:25-42.nKennedy, R. W. 1968. Wood in transverse compression. Forest. Prod. J.18(3):36-40.nKunesh, R. H. 1968. Properties of wood in transverse compression. Forest. Prod. J.18(1):65-72.nMataki, Y. 1972. Internal structure of fiberboard and its relation to mechanical properties. Cited in A. J. Benjamin, 1972. Theory and design of wood and fibre composite material. University of Washington and Syracuse University Press. Pp. 219-253.nPanshin, A. J., and C. de Zeeuw. 1980. Textbook of wood technology. McGraw-Hill Inc., New York, NY.nSchniewind, A. P. 1959. Transverse anisotropy of wood: A function of gross anatomic structure. Forest. Prod. J.9:350-359.nStefansson, F. 1995. Mechanical properties of wood at microstructure level. Report TVSM-5057. Lund Institute of Technology, Lund, Sweden.nTabarsa, T., and Y. H. Chui. 1999. Microscopic observation of wood behaviour in radial compressing. Pages 463-470 in Proc. Fourth International Conference on the Development of Wood Science, Wood Technology and Forestry. Chilterns University College, Buckinghamshire, England.nTabarsa, T., and Y. H. Chui. 2000. Characterizing microscopic behaviour of wood under transverse compression. Part 1: Method and preliminary test results. Wood Fiber Sci.32(2):144-152.nWelonse, J. D., R. L. Krahmer, M. D. Sandoe, and R. W. Jokerst. 1983. Thickness loss in hot-pressed plywood. Forest Prod. J.33(1):227-234.nWolcott, M. P., F. A. Kamke, and D. A. Dillard. 1994. Fundamentals of flakeboard manufacture: Viscoelastic behaviour of the wood component. Wood Fiber Sci.22(4):345-361.nYoungs, R. L. 1957. Mechanical properties of red oak related to drying. Forest. Prod. J.9:315-324.n
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