Recent developments in nonlinear ultrasonic NDE. Thomas Grimsley Ritec, Inc., Warwick, RI USA

Transcription

1 Recent developments in nonlinear ultrasonic NDE Thomas Grimsley Ritec, Inc., Warwick, RI USA

2 Material nonlinearity as a proxy for damage Sources of non-linearity: -kinematical : equations of elasticity for large deformations are inherently nonlinear - Atomistic : in a perfect crystal, lattice anharmonicity will lead to nonlinear elasticity - Dislocations Increasing contributions - Micro cracks - Macro cracks

3 Material nonlinearity : second harmonic generation The most straight forward approach to attempt to measure the elastic nonlinearity of a material acoustically 5 MHz Transducer 10 MHz Transducer 5 Mhz RF Burst Sample Broadband Receiver One consequence of material nonlinearity self distortion of the wave as it propagates, reflected by the generation of higher harmonics Above approach is very difficult to execute well any distortion in system will contribute to measure distortion unless it is accounted for and filtered out

4 4 recent methods not based on Second Harmonic Generation (SHG) -Collinear mixing : two counter propagating waves interact and generate a third wave. -Non-collinear mixing : two waves intersect obliquely and generate a third wave. -Subharmonics from defects (cracks) : f f + f/2 -air coupled emission of higher harmonics localized at defects f f + 2f + 3f +

5 Collinear mixing of waves to measure acoustic nonlinearity Shear + Longitudinal Shear Resonance-like condition for generation of the mixed shear wave: Liu, M., Tang, G, Jacobs, L.J. and Qu, Measuring acoustic nonlinearity by collinear mixing waves. Review QNDE 30, 322 (2010).

6 Collinear mixing of waves to measure acoustic nonlinearity Longitudinal frequency varied Broad band shear transducer used to generate initial shear burst (fixed at 2.3 MHz) and detect mixed shear Liu, M., Tang, G, Jacobs, L.J. and Qu, Measuring acoustic nonlinearity by collinear mixing waves. Review QNDE 30, 322 (2010).

7 Collinear mixing of waves to measure acoustic nonlinearity Resonance condition satisfied Shear = 2.3 MHz Long = MHz Off resonance Shear = 2.3 MHz Long = 11.0 MHz Liu, M., Tang, G, Jacobs, L.J. and Qu, Measuring acoustic nonlinearity by collinear mixing waves. Review QNDE 30, 322 (2010).

8 Collinear mixing of waves to measure acoustic nonlinearity Amplitude of the FFT peak at the difference frequency versus longitudinal frequency Liu, M., Tang, G, Jacobs, L.J. and Qu, Measuring acoustic nonlinearity by collinear mixing waves. Review QNDE 30, 322 (2010).

9 Non-collinear mixing for ultrasonic detection of fatigue 10 MHz longitudinal 5 MHz burst 5 MHz burst Spatial separation of received signal better rejection of system distortion Croxford, A. J. et al. Nonlinear ultrasonic characterization using the noncollinear method. Review QNDE 30, 330 (2010).

10 Non-collinear mixing for ultrasonic detection of fatigue Croxford, A. J. et al. Nonlinear ultrasonic characterization using the noncollinear method. Review QNDE 30, 330 (2010).

11 Non-collinear mixing for ultrasonic detection of fatigue Croxford, A.J., Wilcox, P.D., Drinkwater, B.W. & Nagy, P.B. The use of non-collinear mixing for nonlinear ultrasonic detection of plasticity and fatigue. The Journal of the Acoustical Society of America 126, EL117 (2009).

12 Non-collinear mixing for ultrasonic detection of fatigue Croxford, A. J. et al. Nonlinear ultrasonic characterization using the noncollinear method. Review QNDE 30, 330 (2010).

13 Non-collinear mixing for ultrasonic detection of fatigue Croxford, A. J. et al. Nonlinear ultrasonic characterization using the noncollinear method. Review QNDE 30, 330 (2010).

14 Non-collinear mixing for ultrasonic detection of fatigue Croxford, A. J. et al. Nonlinear ultrasonic characterization using the noncollinear method. Review QNDE 30, 330 (2010).

15 Subharmonic phased array for crack evaluation (SPACE) Ohara, Y. et al. Imaging of closed cracks using nonlinear response of elastic waves at subharmonic frequency. Applied Physics Letters 90, (2007).

16 Subharmonic phased array for crack evaluation (SPACE) Fundamental f Subharmonic f/2 Increasing load opens crack Ohara, Y. et al. Imaging of closed cracks using nonlinear response of elastic waves at subharmonic frequency. Applied Physics Letters 90, (2007).

17 Subharmonic phased array for crack evaluation (SPACE) Ohara, Y. et al. Monitoring growth of closed fatigue crack using subharmonic phased array. Review QNDE 29, 903 (2009).

18 Subharmonic phased array for crack evaluation (SPACE) Repeated experiment with a different loading system Laterally scan the transducer receiver Combination and measure crack depth as a function of position Ohara, Y. et al. Monitoring growth of closed fatigue crack using subharmonic phased array. Review QNDE 29, 903 (2009).

19 Subharmonic phased array for crack evaluation (SPACE) Next step assemble a more rugged system and test on real cracks in pipes Ohara, Y. et al. Monitoring growth of closed fatigue crack using subharmonic phased array. Review QNDE 29, 903 (2009).

20 Non-linear air coupled emission (NACE) Solodov, I. & Busse, G. Nonlinear air-coupled emission: The signature to reveal and image microdamage in solid materials. Applied Physics Letters 91, (2007).

21 Non-linear air coupled emission (NACE) Visuallization different frequency components of sound field above vibrated specimen using special heterodyne laser interferometry Image formed point by point Fundamental second harmonic Solodov, I. & Busse, G. Nonlinear air-coupled emission: The signature to reveal and image microdamage in solid materials. Applied Physics Letters 91, (2007).

22 Non-linear air coupled emission (NACE) Excitation of cracked samples leads to Higher harmonics and ultra-subharmonics Solodov, I. & Busse, G. Nonlinear air-coupled emission: The signature to reveal and image microdamage in solid materials. Applied Physics Letters 91, (2007).

23 Non-linear air coupled emission (NACE) Solodov, I. & Busse, G. Nonlinear air-coupled emission: The signature to reveal and image microdamage in solid materials. Applied Physics Letters 91, (2007).

24 Non-linear air coupled emission (NACE) Solodov, I. & Busse, G. Nonlinear air-coupled emission: The signature to reveal and image microdamage in solid materials. Applied Physics Letters 91, (2007).

25 SUMMARY and FUTURE OUTLOOK Many avenues left to explore in this area Wave mixing ( collinear and noncollinear) -what choices of frequencies are the best for defect detection? -what choices of modes (shear or longitudinal) are the best for various detects? NACE -Many possibilities for choices of harmonics, ultrasubharmonics, and how sensitive they are to various flaws Thanks for your attention