Determining the Young's modulus of solid wood by considering the fundamental frequency under the free-free flexural vibration mode

The Young's modulus in the longitudinal direction of a Sitka spruce specimen was determined by conducting free-free flexural vibration tests based on Euler-Bernoulli's and Timoshenko's vibration theories. Comparing the Young's moduli obtained considering these theories, an equation to calculate the Young's modulus by considering only the fundamental frequency was formulated by modifying the equation derived from the Euler-Bernoulli's theory. The modification was conducted with the consideration that the modified equation was applicable to various wood species with a wide range of length/depth ratio. Additionally, the accuracy of the proposed equation was examined using a statistical method for comparing the Young's moduli obtained considering the aforementioned theories. Using the proposed equation, accurate Young's moduli could be determined considering only the fundamental frequency, with a reduced influence of the length/depth ratio. The statistical analysis results indicated that the proposed equation can effectively yield accurate Young's moduli for various wood species with a wide range of length/depth ratio.