On the effect of the number of annual growth rings, specific gravity and temperature on redwood elastic modulus

Abstract

Due to the natural origin of wood, physical parameters such as specifi c gravity and the number of growth rings per inch affect its properties. In this study, to evaluate the effect that these physical parameters have on the elastic properties of wood, particularly on elastic modulus, a uniaxial compression test was performed on specimens. These specimens consisted of solid cubes of the Redwood species of wood with a width of 10.16 cm. Three different temperature conditions—ambient temperature (18°C), cold temperature (-28°C) and hot temperature (65°C) were used to carry out the tests. Specifi c gravity ranged from 0.29 to 0.45, and the number of growth rings per inch varied from 2 to 24 rings per inch. The minimum moisture content in the specimens was 2%, and reached a maximum of 16% according to the temperature conditions. The results from the statistical analysis indicated that the effect that the number of growth rings per inch has on elastic modulus is more signifi cant than the effects of specifi c gravity or even of temperature. As a consequence, we suggest that the number of growth rings per inch can be used as a predictor for wood elastic modulus.