Shear Modulus of Open-Hole Sitka Spruce Obtained from a Torsional Vibration Test

Abstract

In this study, torsional vibration tests of open-hole Sitka spruce samples were performed, and the influence of the diameter and position of the hole on the value of the nominal shear modulus were examined. The nominal shear modulus value decreased as the diameter of the hole increased and the hole position approached the mid-length of the sample. Nevertheless, such decrements were gentler than the nominal elastic moduli obtained from the longitudinal and flexural vibration tests obtained in a previous publication. A formula for deriving the nominal shear modulus of open-hole sample was proposed by modifying the equation obtained in a previous study, and the accuracy was improved, although the numbers of parameters contained in the equation increased.