Selection of optimal artificial boundary condition (ABC) frequencies for structural damage identification

• Selection criteria for optimal ABC frequencies in structural damage identification are proposed.
• Sensitivity expressions for one-pin and two-pin ABC frequencies are derived.
• Contributions of the underlying mode shapes in the ABC frequencies are calculated and used for the selection.
• Numerical studies are carried out to validate the performance of proposed selection criteria.
• Results demonstrate that with proposed selection criteria, reliable damage identification performance can be obtained using the selected ABC frequencies.

In this paper, the sensitivities of artificial boundary condition (ABC) frequencies to the damages are investigated, and the optimal sensors are selected to provide the reliable structural damage identification. The sensitivity expressions for one-pin and two-pin ABC frequencies, which are the natural frequencies from structures with one and two additional constraints to its original boundary condition, respectively, are proposed. Based on the expressions, the contributions of the underlying mode shapes in the ABC frequencies can be calculated and used to select more sensitive ABC frequencies. Selection criteria are then defined for different conditions, and their performance in structural damage identification is examined with numerical studies. From the findings, conclusions are given.