Detection of fatigue cracks in a beam using a spatio-temporal dynamical system identification method

The identification of fatigue cracks in a beam is investigated in this paper. It is shown that due to the influence of the elastic nonlinearity of fatigue cracks, the homogeneity, along the length of the beam, of the spatio-temporal dynamics of the vibrating beam is destroyed. By using spatio-temporal dynamical system identification techniques, a new approach is developed to detect this nonhomogeneity. The cracked beam is divided into several spatial regions and a coupled map lattice (CML) model is identified and verified in one of the regions using an orthogonal forward regression (OFR) least-squares algorithm. This CML model is then used to predict the dynamical behaviour of the other regions and in this way to detect the nonhomogeneity of the overall system.