Residual fatigue life estimation using a nonlinear ultrasound modulation method

Predicting the residual fatigue life of a material is not a simple task and requires the development and association of many variables that as standalone tasks can be difficult to determine. This work develops a modulated nonlinear elastic wave spectroscopy method for the evaluation of a metallic co...

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Bibliographic Details
Published in:Smart materials and structures 2015-02, Vol.24 (2), p.25040-16
Main Authors: Malfense Fierro, Gian Piero, Meo, Michele
Format: Article
Language:English
Subjects:
fatigue
Fatigue life
Mathematical models
Measurement methods
Modulation
NDT
Nonlinearity
residual life
Sidebands
Tasks
Ultrasonic testing
Ultrasound
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Summary:Predicting the residual fatigue life of a material is not a simple task and requires the development and association of many variables that as standalone tasks can be difficult to determine. This work develops a modulated nonlinear elastic wave spectroscopy method for the evaluation of a metallic components residual fatigue life. An aluminium specimen (AA6082-T6) was tested at predetermined fatigue stages 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 (two signal output system) 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. A baseline-free method was developed by linking a theoretical model, obtained by combining the Paris law and the Nazarov-Sutin crack equation, to experimental nonlinear modulation measurements. The results showed good correlation between the derived theoretical model and the modulated nonlinear parameter, allowing for baseline-free material residual fatigue life estimation. Advantages and disadvantages of these methods are discussed, as well as presenting further methods that would lead to increased accuracy of residual fatigue life detection.
ISSN:0964-1726
1361-665X
DOI:10.1088/0964-1726/24/2/025040