Damage Assessment in Solids through Nonlinear Ultrasonics in the Time Domain

This study reports the main results obtained from the application of a NDT method based on nonlinear ultrasounds and denoted as Scaling Subtraction Method (SSM) to several case studies, involving different types of consolidated granular media and different damage mechanisms. The effectiveness of the SSM in describing damage evolution is discussed with reference to both diffuse damage, as induced by mechanical or thermal loads and localized damage, as in the case of degradation of the interfacial surfaces between different portions of a solid under chemical attack. Limitations and potentialities of the method are discussed with respect to other damage assessment indicators.