Measurement of elastic nonlinearity using remote laser ultrasonics and CHeap Optical Transducers and dual frequency surface acoustic waves

• Published in: Ultrasonics Vol. 48; no. 6; pp. 471 - 477
• Main Authors: Collison, I.J., Stratoudaki, T., Clark, M., Somekh, M.G.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-11-2008; Elsevier
• Subjects: Acoustical measurements and instrumentation; Acoustics; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Fused silica; Materials science; Materials testing; Nonlinear ultrasound; Optical transducers; Parametric interaction; Phase modulation; Physics; Ultrasonics, quantum acoustics, and physical effects of sound; Parametric interaction; Nonlinear ultrasound; Optical transducers; Phase modulation; Fused silica; Non linear material; Acoustic measurement; Stress wave; Stress strain relation; Acoustic surface waves; Aluminium; Elastic wave; Optical frequency; Low frequency; Silica; Sound velocity; Non linear acoustics; Ultrasonic control; Laser ultrasonics; Non linear effect; High frequency; Non destructive test; Ultrasonic transducer; Non contact measurement
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/j.ultras.2008.07.003

A nonlinear ultrasonic technique for evaluating material elastic nonlinearity has been developed. It measures the phase modulation of a high frequency (82
MHz) surface acoustic wave interacting with a low frequency (1
MHz) high amplitude stress inducing surface acoustic wave. A new breed of optical transducers has been developed and used for the generation and detection of the high frequency wave. The CHeap Optical Transducer (CHOT) is an ultrasonic transducer system, optically activated and read by a laser. We show that CHOTs offer advantages over alternative transducers. CHOTs and nonlinear ultrasonics have great potential for aerospace applications. Results measuring changes in ultrasonic velocity corresponding to different stress states of the sample are presented on fused silica and aluminium.