Wood specific gravity-mechanical property relationship at species level

Based on the data set of specimen tests on 16 timber species belonging to four distinct wood categories, the specific gravity-mechanical property relationship at species level was examined, and differences in the relationship between species from distinct wood categories were discussed. The linear equation (S = a + bG) was compared with the curvilinear one (S = αGβ) in terms of the goodness at predicting mechanical properties through specific gravity at species level. The specific gravity-mechanical property relationship, to a differing extent, varies with mechanical properties and wood categories. Among three mechanical properties studied, MOR is most closely and almost linearly related to specific gravity, followed by Cm ax, whereas MOE is poorly and least linearly related to specific gravity. In general, the relationship between MOE and specific gravity in a species from the ring-porous category is stronger than in a species from the diffuse-porous category. It appears that Cmax in a species from the second softwood category and the ring-porous category is more closely related to specific gravity than in a species from the first softwood category and the diffuse-porous category, respectively. In addition, MOE in a softwood species is generally less related to specific gravity as compared to a hardwood species. Yet, Cmax in a softwood species appears more closely related to specific gravity. Overall, the curvilinear equation is better than the linear one at predicting mechanical properties (especially MOE) in a species.