Damage detection in structural elements taking into account a crack contact model.

FERNANDO BUEZAS; MARTA B. ROSALES; CARLOS P. FILIPICH

San Luis, Argentina

Congreso; XVII Congreso sobre Métodos Numéricos y sus Aplicaciones (ENIEF 2008).; 2008

Asociacion Argentina de Mecánica Computacional y Universidad Nacional de San Luis

This paper deals with the crack detection in structural elements by means of a generic algorithm optimization method. Both beam-like structures and arbitrary shaped structural elements may be handled through bi- and three dimensional models. The crack model takes into account the existance of contact. Many of the methods to detect a crack in beam-like structures are based onlinear one-dimensional models and are notstraightforwardly applicable to structures such as beams or arcs with anopen crack or a breathing crack without or with contact. The present studydeals with bi- and three-dimensional models to handle the dynamicsof a structural element with a transversebreathing crack. The methodology is not restricted to beam-like structures since it may be applied to any arbitrary shaped 3D element. The crack is simulated as a notch or a wedge with aunilateral Signorini´s contact model. The contact may be partial ortotal. All the simulations are carried out using the partial differentialsolver of the general purpose, finite element code FlexPDE. A genetic algorithm (GA) optimization method is successfully employed forthe crack detection. The dynamic response at some points of the damaged structuresare compared with the solution of the computational (FE) model using leastsquares for each proposed crack depth and location. An objective functionarises which is then optimized to obtain an estimate of both parameters. Physical experiments were performed with a cantilever damaged beam and the resulting data used as input in the detection algorithm.