Abstract:

The characteristics of transverse fracture of Chinese Fir from macro and microcosmic, and the mechanism of strong toughness of wood was studied in this paper. The results are:The spread manner of transverse crack is that crack crazes through the grain firstly, and then rupture toughly along the cross section. The spread process of crack is divided into three steps:linearity, stabilization and non stabilization. The crazing toughness is independent of sample dimensions, for it is an inherent property of wood. Because of more cell and more layer with fibre reinforced structure, wood have a good toughness for transverse fracture. So in the low working stress condition, it could not be broken by the stress singularity from the point of the crack. Considered of this, when making safety designs of the wood components, traditional strength criterion could still be adopted and it is enough to calculate the general strength of remained dimension.

Key words: Transverse fracture of wood, Fracture toughness, Mechanism of strong toughness, Strength criterion