Rheological consideration in fracture of wood in lateral tension

Abstract

For the purpose of elucidating the effect of rheological property of wood on lateral tensile fracture, failure strain, elastic modulus, and creep at various temperature conditions were measured. And, relationship between the degree of softening or fluidity and lateral tensile failure strain was examined. To discuss the fracture mechanism from the results of the failure strains, broken specimens were observed and each appearance ratio of fractures in different tissue was calculated. The results obtained are as follows: (1) Failure strains were reduced in the temperature from 80 to 95 °C, because the weakest parts as a starting point of fracture changed in all of the specimens and the weakest parts for fractures were increased with temperature rise. (2) The effects of softening of wood are important for increasing failure strains up to the temperature range in which the fracture mechanism changes. (3) Creep deformation, that is, fluidity was included in the wood deformation process, and the fluidity had different characteristics dependent on the anatomical characteristics. It also became clear that the creep deformation measured in the load range of this study did not affect the increase in failure strain significantly.