Summary
The cracking patterns of load induced cracks were studied by in-situ testing of compact tension specimens within the specimen chamber of a scanning electron microscrope. The cracks propagated in a generally straight path parallel to the grain, regardless of the orientation of the notch. On a microscopic scale, the crack could not be described as an ideal parallel-walled crack as assumed in fracture mechanics models. Many irregularities such as tortuosities, branching, discontinuities and bridging between the crack walls could be seen. Observations were carried out at the tip of the stable crack and at the same zone after the crack was induced to propagate beyond it. The processes taking place in this zone are discussed. The implication of these observations on the applicability of linear elastic fracture mechanics to wood are also discussed.
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When this work was carried out, Dr. Bentur was on leave at Purdue University, West Lafayette, Indiana
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Mindess, S., Bentur, A. Crack propagation in notched wood specimens with different grain orientations. Wood Sci. Technol. 20, 145–155 (1986). https://doi.org/10.1007/BF00351026
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DOI: https://doi.org/10.1007/BF00351026