Dynamic modulus of elasticity of drilled wooden beams

In this study, researchers attempted to investigate the effects of drilling and hole widening on the dynamic response of wood using nondestructive methods. Clear and sound rectangular (2 × 2 × 36 cm R × T × L) bars were prepared from Beech timber (Fagus orientalis) and drilled in four steps with 3, 5, 8 and 10-mm diameters at central points in length on the tangential (LT) surface in the radial (LR) direction. To evaluate the longitudinal modulus of elasticity, the free–free bars before and after drilling procedure were brought to free flexural vibration test. To study the effects of stepwise hole widening, the dynamic evaluations were compared with two flexural vibrations parallel to LR and LT surfaces. The holes decreased the longitudinal modulus of elasticity values when the bars were vibrated in LR, while the values in LT remained significantly constant throughout the stepwise drilling. The differences due to longitudinal modulus of elasticity values comparing LR and LT free flexural vibrations were proposed as defect indicators.