L.D. Chiwiacowsky, H.F. de Campos Velho, P. Gasbarri (2004): The Damage Identification Problem: A Hybrid Approach, Journal of Sound and Vibration (submitted).

Abstract: The present investigation is focused on the solution of a dynamic inverse problem which is concerned with the assessment of damage in structures by means of measured vibration data. This inverse problem has been presented as an optimization problem and has been solved through the use of the conjugate gradient method with the adjoint equation, i.e. the variational approach. The stiffness estimation problem has already been solved in a satisfactory form through the use of the variational approach, where spring-mass systems with one and two degrees-of-freedom (DOF) have been considered. However, when a higher DOF structure is considered, the simple application of the variational approach is not more satisfactory, being necessary the application of an additional methodology. This work presents a hybrid approach to overcome this difficulty, where the Genetic Algorithm (GA) method with the new epidemical genetic operator is employed to generate a primary solution which is employed as the initial guess for the conjugate gradient method (CGM). The application of this new approach has been showed that better results can be achieved. The damage estimation has been evaluated using simulated experimental data, and the reported results are concerned with a lumped-parameter system.