Comparison of vibration and wave propagation approaches applied to assess damage influence on the behavior of Euler–Bernoulli beams

In the present work, the damage influence on the vibrational behavior and on the wave propagation issues of a slender Euler–Bernoulli beam is investigated. In the vibration framework, the damage is assessed in the modal space by considering changes in the reduced flexibility matrix of the structure, which is only related to the measured degrees of freedom and may be accurately estimated from a few of the lower frequency modes in a modal test. In the wave propagation framework, on the other hand, the presence of damage is perceived in the time domain by an early echo output generated by the inhomogeneity within the beam in an impact test. A slender aluminium beam with distinct imposed damage scenarios is considered for numerical analysis. The modal properties required to estimate the reduced flexibility matrix of the beam and its impulse response are assumed to be available from modal and impact tests, respectively. In the numerical analysis performed, both approaches showed sensitivities to damage that enable them to be applied for damage identification purposes.