An Estimation of Dynamic Modulus of Elasticity in Cantilever Flexural Timber Beams

Abstract

Due to considerable influence of shear deflection and rotary motion, the modulus of elasticity is hardly obtainable in fixed-free flexurally-excited (cantilever) beams. For isotropic materials, Timoshenko has proposed a set of curves to correct the fixed-free modal frequencies as the radius of gyration and free length; however, its performance for wood was not sufficiently conclusive. In this study, rectangular beams of pine wood were tested in a fixed-free condition, altering the free length to height ratios in a proper extent and comparing them to their reference free-free data in terms of natural frequency and dynamic modulus of elasticity shifts. The equality of two pairs of fixed-free versus free-free data, for both frequency and dynamic modulus, was significantly confirmed. The correlation coefficient between experimental and calculated fixed-free frequencies was high enough, and however the correlation coefficient of the modulus of elasticity was rather low.