Research Of Structural Damage Identification On Uncertainty

Under the influence of uncertain factors, uncertainty becomes the attribute of measurement data. And the damage detection turns into an indeterminate problem. Many theories and methods for damage identification have been presented, but the research is inadequate for the structural damage identification under uncertain situations. Considering the state-of-the-art and state-of-the-practice of the structural damage identification, the dissertation is devoted to the numerical simulation and experimental vertification for the damage identification under uncertainty, on the basis of existing structural damage identification methods.When the dynamic modal parameters are used to detect the damage of structure, the result will be influced by the error generated by the uncertainty, sometimes the practical damage of structure can not be identified. So it's necessary to study the influence of the uncertainty. Structural damage identification is an inverse problem, and can be treated as an optimization problem. The nonliner least square of the damage index functions of the test data and the finite element prediction is used as the objective function of the optimization model for the damage identification. Conlude the different types of error objective functions. According to the measured data and identification principle identification methods can be divided into the method based on frequency, mode shape, frequency and mode shape, frequency and mode curvature, modal flexibility and so on. In this work, Monte Carlo simulation technique are used to qualify and quantify the test noises effect to the identified results.The illustrative examples of a pipe model and a truss model are used to perform the numerical simulation, and a test on a pipe is used to perform the experimental validation, verifying the efficiency of these methods using different objective functions. Under every damage condition, giving different level of uncertainty, dependent on the analysis of the result, the sensitivity of different damage indices is compared.In the last chapter of this dissertation, the research word is summarized and the future extensions of the relevant study are pointed out.