Measurement of material nonlinearity using surface acoustic wave parametric interaction and laser ultrasonics

Theodosia Stratoudaki, Robert Ellwood, Steve D. Sharples, Matthew Clark, Michael G. Somekh, Ian J. Collison

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

A dual frequency mixing technique has been developed for measuring velocity changes caused by material nonlinearity. The technique is based on the parametric interaction between two surface acoustic waves (SAWs): The low frequency pump SAW generated by a transducer and the high frequency probe SAW generated and detected using laser ultrasonics. The pump SAW stresses the material under the probe SAW. The stress (typically 5 MPa) is controlled by varying the timing between the pump and probe waves. The nonlinear interaction is measured as a phase modulation of the probe SAW and equated to a velocity change. The velocity-stress relationship is used as a measure of material nonlinearity. Experiments were conducted to observe the pump-probe interaction by changing the pump frequency and compare the nonlinear response of aluminum and fused silica. Experiments showed these two materials had opposite nonlinear responses, consistent with previously published data. The technique could be applied to life-time predictions of engineered components by measuring changes in nonlinear response caused by fatigue.

Original languageEnglish
Pages (from-to)1721-1728
Number of pages8
JournalJournal of the Acoustical Society of America
Volume129
Issue number4
DOIs
Publication statusPublished - 30 Apr 2011
Externally publishedYes

Keywords

  • nondestructive evaluation
  • fatigue analysis
  • microscale defects
  • acoutic waves

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