The dynamic non-linear behaviour of damaged structures is becoming of primary importance in damage detection and health monitoring. Numerical and analytical simulations are used to predict damaged structure dynamic responses for a comprehensive understanding of the phenomenology and the identification of key parameters enabling an efficient and reliable defect characterisation. Because of the inadequacy of classical non linear material model to reproduce the hysteretic behaviour of fatigue damaged materials, a new material model was implemented in a FE code. This new material model is based on Presaich and Mayergoyz (PM) space and it is capable of reproducing the material classical material non linearity, the hysteretic behaviour, and the memory effect typical of damaged materials. The PM space model was tested against a classical non-linear model in a wave propagation investigation on a composite beam. Various levels of damages were introduced in different locations. The changes introduced by the damages modelled using the classical approach and the PM space were analysed in terms of the strain amplitude changes. The results showed that the analysis of the harmonics generated by the presence of the damage zone can be used to detect fault presence, and therefore can be implemented in a new class of innovative non-destructive techniques that provide higher sensitivity in detecting and imaging incipient damage than those obtained by linear acoustic technologies.
展开▼
