SEDL / STP / STP405-EB / STP45149S

Anisotropy in Wood

Ethington, R. L.
Technologist and engineer, U. S. Forest Products Laboratory, Forest Service, U. S. Department of Agriculture,

Hilbrand, H. C.
Technologist and engineer, U. S. Forest Products Laboratory, Forest Service, U. S. Department of Agriculture,

Pages: 18    Published: Jan 1966

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Abstract

Wood is an anisotropic, cellulosic, semicrystalline, cellular material. The tissue making up the woody substance is oriented such that mechanical properties are generally higher along the bole of a tree than across the bole. The mechanical properties (elastic, strength, and rheologic) exhibit strong orientation effects and are complicated by the addition of growth irregularities. Mechanically, clear wood obeys the laws of elastic orthotropic materials, and its failure characteristics are well described by strain energy of distortion-type theory.