Identification of Damage in Thin-Walled Curved Beams by means of Vibration Analysis

FRANCO EZEQUIEL DOTTI; VÍCTOR HUGO CORTÍNEZ; MARCELO TULIO PIOVAN

San Pablo

Congreso; DINAME 2011: XIV International Symposium on Dynamic Problems of Mechanics; 2011

Associação Brasileira de Métodos Computacionais em Engenharia

A theoretical model for the dynamic analysis of damaged thin-walled curved beams is presented. This model incorporates bending and warping effects of shear flexibility by means of a linearized formulation based on the principle of virtual work. A beam iso-parametric finite element with five nodes and seven degrees-of-freedom per node is employed to solve the governing equations. Damage is considered in the model by modifying the sectional properties of a single finite element having an appropriate length. In order to perform identification of failure parameters, damage is treated as a fatigue crack located in a boundary of the beam cross-section. Location and depth of the crack are identified by means of the minimization of a target function. This function is defined in terms of differences of certain dynamic parameters among numerical and experimental values. As dynamic indices of damage, forced response and natural frequencies are employed. Two different optimization algorithms –Differential Evolution and Simulated Annealing– are employed to perform the optimization and their results are compared. Numerical results and comparisons with shell models illustrates that the present beam model is accurate enough to perform damage detection in thin-walled curved beams by means of frequency analysis.