Abstract
Wood is one of the few engineering materials for which design codes specify that the applied stress be contingent on the duration of the load. This is in recognition of the fact that the strength of wood appears to degrade with time when under stress. This paper describes a set of experiments in which the kinetics of wood fracture are examined. It is shown that the present results and those of earlier workers can be fully explained by a relatively simple model and mathematical analysis, based on fracture mechanics. According to these results, the delayed failure of wood is caused by subcritical crack growth. The model helps to reveal what must be done to incorporate the duration-of-load effect into timber design in a probabalistic manner.
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Nadeau, J.S., Bennett, R. & Fuller, E.R. An explanation for the rate-of-loading and the duration-of-load effects in wood in terms of fracture mechanics. J Mater Sci 17, 2831–2840 (1982). https://doi.org/10.1007/BF00644658
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DOI: https://doi.org/10.1007/BF00644658