Modelling localized nonlinear damage and analysis of its influence on resonance frequencies

Nonlinear acoustic techniques have proven to be extremely sensitive for damage detection in structural materials or composites. Damage characterization, however, also involves localization and quantification, as well as detection. For this purpose, models developed to describe the response of localized damage (due to micro-features) to acoustic excitation may help to study the influence on the specimen resonance frequency of the position, length and damage level of the defective region. We present here some numerical results to show how nonlinear acoustic measurements of the resonance frequencies of higher modes may be used for damage localization, with possible applications in non-destructive testing of materials.