In
this paper it is shown that natural frequency and antiresonant
frequency shifts induced by a damage contain information on
certain generalized Fourier coefficients of the stiffness
variation caused by the damage itself in a vibrating beam. Under
the assumption that the damaged beam is a perturbation of the
undamaged one, a reconstruction procedure based on an iterative
algorithm is proposed. The theoretical results are confirmed by a
comparison with dynamic measurements on steel beams with localized
damages, either under axial or bending vibration.
