Noncontact monitoring of surface-wave nonlinearity for predicting the remaining life of fatigued steels
Year: 2001
Type: article
Abstract: A nonlinear acoustic measurement is studied for fatigue damage monitoring. An electromagnetic acoustic transducer (EMAT) magnetostrictively couples to a surface-shear-wave resonance along the circumference of a rod specimen during rotating bending fatigue of carbon steels. Excitation of the EMAT at half of the resonance frequency caused the standing wave to contain only the second-harmonic component, which was received by the same EMAT to determine the second-harmonic amplitude. Thus measured surface-wave nonlinearity always showed two distinct peaks at 60% and 85% of the total life. We attribute the earlier peak to crack nucleation and growth, and the later peak to an increase of free dislocations associated with crack extension in the final stage. This noncontact resonance-EMAT measurement can monitor the evolution of the surface-shear-wave nonlinearity throughout the metal’s fatigue life and detect the pertinent precursors of the eventual failure.
Source: Journal of Applied Physics
DOI: 10.1063/1.1376668
Authors: Hirotsugu Ogi, Masahiko Hirao, Shinji Aoki
Institution: The University of Osaka
Language: English
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2018204651