This paper deals with a dynamic method for damage detection in
beams. Under the assumption that the damaged beam is a
perturbation of the undamaged one, it is shown that natural
frequency and antiresonant frequency shifts induced by structural
damage contain information on certain generalized Fourier
coefficients of the stiffness variation caused by the degradation.
A reconstruction method based on this property is proposed to
solve the inverse problem. Cases with pseudoexperimental and
experimental data are discussed. The results are in good agreement
with the theory, provided that average frequency and antiresonant
frequency shifts are bigger than modeling/measurement errors.
