Structural modal identification and damage detection with incomplete data utilized by genetic algorithm optimization

Abstract

This research presented a procedure to automatically identify the modal characteristics of structures to detect and quantify any localized damage of structures in frequency domain. This process uses the acceleration frequency response of the selected degree of freedoms, some natural frequency of the damaged structure and mode shapes of the undamaged Finite Element (FE) model to identify the structural stiffness of the damaged structure containing the damping ratio. The incomplete data in the unmeasured degree of freedom will be updated using a genetic optimization algorithm. The accuracy and efficiency of the proposed method have been tested on a 25 elements truss subjected to a harmonic load with sweep frequency. Optimization results demonstrated that the proposed method is capable of precisely identifying the modal characteristics and stiffness reduction factor of the damaged structure using genetic optimization algorithm along with 5% noise in the input force and response of the system in all studied cases.