Effect of the specimen configuration on the accuracy in measuring the shear modulus of western hemlock by torsional vibration test

Abstract

The shear moduli of solid wood in longitudinal–tangential and longitudinal–radial planes were obtained by conducting a torsional vibration test and subsequent numerical analyses on western hemlock specimens by fixing the thickness as 10 mm and varying the width and length in the ranges of 20–80 mm and 100–400 mm, respectively. In the numerical analyses, the shear modulus in the tangential–radial planes was varied, and its effect was also examined as well as those of the width and length of the model. The results obtained indicated that the effect of the shear modulus in the tangential–radial plane was enhanced as the width increased and the length decreased. However, the shear modulus in the wider plane of the specimen could be obtained accurately by reducing the effect of the shear modulus in the tangential–radial plane when appropriate ranges of the width and length were determined. From the numerical and experimental results, the shear moduli in the longitudinal–tangential and longitudinal–tangential planes were accurately obtained when the width was in the range of 20–40 mm and the length was in the range of 250–400 mm.