Shear moduli in the longitudinal-radial and radial-tangential planes of Sitka spruce measured by torsional vibration tests

The shear moduli (SM) of solid wood in the longitudinal-radial (LR) and radial-tangential (RT) planes of Sitka spruce are extremely different from each other and were obtained via a torsional vibration (TV) test by varying the aspect ratios and conducting subsequent numerical analyses. The SM in both planes were accurate, when the aspect ratios of the specimens were appropriately selected, even though the SM around the torsional axis were extremely different from each other.