Damage Detection in Structural Elements Taking Into Account a Crack Contact Model

Abstract

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 on linear onedimensional
models and are not straightforwardly applicable to structures such as beams or arcs with an open crack or a breathing crack without or with contact. The present study deals with bi- and threedimensional models to handle the dynamics of a structural element with a transverse breathing 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 a unilateral Signorini’s contact model. The contact may be partial or total. All the simulations are carried out using the partial differential solver of the general purpose, finite element code FlexPDE. A genetic algorithm (GA) optimization method is successfully employed for the crack detection. The dynamic response at some points of the damaged structures are compared with the solution of the computational (FE) model using least squares for each proposed crack depth and location. An objective function arises 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.