Measuring Dispersion Curves for Bending Waves in Beams: A Comparison of Spatial Fourier Transform and Inhomogeneous Wave Correlation

Abstract

In this paper, two methods to acquire the dispersion of bending waves in beams are compared: the spatial Fourier transform and inhomogeneous wave correlation. Two examples of beams with non-standard dynamic properties are given: layered beams made out of wood (cross laminated timber) and beams with a periodically varying thickness profile. Dynamic testing, such as modal analysis or wave speed measurements, can be used to determine the elastic properties of materials. A direct measurement of the dispersion facilitates an easy assessment of the stiffness parameters over a wide frequency range for layered beams made out of orthotropic layers. The efficiency of structural metamaterials, elastic structures engineered to exhibit band gaps in which waves are quickly attenuated, can also be addressed through the dispersion relation.