A multiple-damage location assurance criterion based on natural frequency changes

A new method for locating multiple damage sites in elastic structures is introduced. It uses only the natural frequencies for diagnosis and obviates the need to have complete experimental mode shapes. Results from three damaged structures are presented. A 2-bar truss illustrates the basis for the method, a 15-bar truss shows its use with symmetrical structures, and a redundant-bar truss is used to compare the new method with that of Pandey and Biswas. Correct predictions of the location and relative amounts of damage at multiple sites are obtained, even when low damage levels are present in the structure.