Identification of damage in beam structures using flexural wave propagation characteristics

An experimental method of detecting damage using the flexural wave propagation characteristics is proposed. To monitor change in structural properties due to damage, the frequency-dependent variation of the wavenumber, wave speed, and the dynamic properties were measured in the frequency ranges of flexural vibration. The measured frequency-dependent variation was compared to those measured when undamaged. The beam transfer function method was used to obtain the dynamic properties. The location and magnitude of damage were identified using the property that it has significant impact on the system potential energy. When the wave propagates through a medium, the total system energy remains mostly unchanged, but its form changes between potential and kinetic energy. The wave propagation characteristics are affected most when damage occurs at locations where the wave energy is in the form of the potential energy. The validity of the proposed method was confirmed by experimentation. The various locations of damage imposed on the beam structures with different magnitudes were identified accurately.