Introspective of Damage Detection Methods Based on Natural Frequencies Changes and Sensitivities

This manuscript deals with damage identification algorithms based on natural frequency sensitivities/changes. Philosophical aspects and inherent features between new methods and variants of existing ones are theoretically and numerically elucidated and a clear understanding on the importance to look for certain classes of solutions in particular bounded domains is ascertained. Based on these latter motivations methods more performing, than existing ones, are discussed and their effectiveness is successfully shown versus practical problems by making use of the current available calculators. The methods are designed for both differential and finite damage.