A structural damage identification method for plate structures

In this study, a new structural damage identification method (SDIM) is developed for plate structures. It is derived from the dynamic equation of motion for damaged plates, in which local damages are characterized by the use of a damage distribution function. In contrast with most of the existing modal-data-based SDIMs, which require the modal data only measured in both the intact and damaged states, the present SDIM requires, the modal data measured in the intact state and the frequency response function (FRF)-data, instead of the modal data, measured in the damaged state. Two strategies for making the inverse-problem of damage identification well-posed are introduced in connection with the present SDIM: (1) by virtue of using FRF-data, a sufficient number of equations can be derived by choosing as many sets of excitation frequency and FRF- measurement points as needed; and (2) a concept of reduced-domain method can be applied to iteratively search out and remove damage-free zones from the original domain of the problem, which finally leaves only the zones with local damages within a few iterations. The feasibility of the present SDIM is validated through some numerically simulated damage identification tests taking into account the random noises in FRF-data.