Measurement of the shear moduli of spruce by torsional vibration tests using a pair of specimens with different aspect ratios

The shear moduli (SM) of solid wood in longitudinal-radial (LR) and longitudinal-tangential (LT) planes were obtained via a torsional vibration (TV) test by varying the aspect ratios of Sitka spruce specimens and conducting subsequent numerical analyses. A pair of specimens with different aspect ratios was used to separate the SM in the LR and LT planes from each other, and the effect of the aspect ratio was examined. The experimental and numerical results indicated that the SM can be accurately obtained via TV test, when the aspect ratios of the specimens are appropriately determined.