Open Access Open Access  Restricted Access Subscription or Fee Access

Baseline-Free Estimation of the Residual Fatigue Life Using a Modulated Nonlinear Ultrasound Method



This work develops a modulated nonlinear elastic wave spectroscopy (NEWS) method for the evaluation of a metallic components residual fatigue life. An aluminium specimen (AA6082-T6) was tested at predetermined points throughout its fatigue life using a dual-frequency ultrasound method. A modulated nonlinear parameter was derived, which described the relationship between the generation of modulated (sideband) responses of a dual frequency signal and the linear response. The sideband generation from the dual frequency was shown to increase as the residual fatigue life decreased, and as a standalone measurement method it can be used to show an increase in a materials damage. Although analytical evaluation of the method was required to develop a baseline-free method, work done by Meo and Amerini combined the Paris law and the Nazarov-Sutin crack equation developing the theoretical model. The results showed good correlation between the derived theoretical model and the modulated nonlinear parameter, allowing for material residual fatigue life estimation.

Full Text: