A crack detection technique based on nonlinear acoustics is investigated in this study. Acoustic waves at a chosen frequency are generated using an actuating lead zirconate titanate (PZT) transducer, and they travel through the target structure before being received by a sensing PZT wafer. Unlike an undamaged medium, a cracked medium exhibits high acoustic nonlinearity which is manifested as harmonics in the power spectrum of the received signal. Experimental results also indicate that the harmonic components increase nonlinearly in magnitude with increasing amplitude of the input signal. The proposed technique identifies the presence of cracks by looking at the two aforementioned features: harmonics and their nonlinear relationship to the input amplitude. The effectiveness of the technique has been tested on aluminum and steel specimens. The behavior of these nonlinear features as crack propagates in the steel beam has also been studied.
Huang, M., Jiang, L., Liaw, P.K., Brooks, C.R., Seeley, R. and Klarstrom, D.L. (1998). Using acoustic emission in fatigue and fracture materials research. JOM-e, 50(11), http://www.tms.org/pubs/journals/JOM/9811/Huang/Huang-9811.html
2.
Sophian, A., Tian, G.Y., Taylor, D. and Rudlin, J. (2001). Electromagnetic and eddy current NDT: a review . Insight (UK), 43(5), 302-306.
3.
Chondros, T.G. , Dimarogonas, A.D. and Yao, J. (1998). A continuous cracked beam vibration theory. Journal of Sound and Vibration, 215(1), 17-34.
4.
Liang, C., Sun, F.P. and Rogers, C.A. (1994). Coupled electro-mechanical analysis of adaptive material systems - determination of the actuator power consumption and system energy transfer. Journal of Intelligent Material Systems and Structures, 5, 12-20.
5.
Giurgiutiu, V. and Rogers, C.A. (1997). Electro-mechanical (E/M) impedance method for structural health monitoring and non-destructive evaluation. International Workshop on Structural Health Monitoring, Stanford. CA, USA, pp. 433-444.
6.
Park, G., Sohn, H., Farrar, C.R. and Inman, D.J. (2003). Overview of piezoelectric impedance-based health monitoring and path forward. The Shock and Vibration Digest , 35(6), 451-463.
7.
Green, R.E. (1973). Ultrasonic Investigation of Mechanical Properties , New York and London: Academic Press.
8.
Rose, J.L. (1999). Ultrasonic Waves in Solid Media, UKCambridge University Press.
9.
Kim, S.B. and Sohn, H. (2007). Instantaneous reference-free crack detection based on polarization characteristics of piezoelectric materials . Smart Materials and Structures, 16(6), 2375-2387(13).
10.
Staszewski, J.W. (2003). Structural health monitoring using guided ultrasonic waves. In: Holnicki-Szulc, J. and Mota Soares, C.A. (eds), Advances in Smart Technologies in Structural Engineering, pp. 117-162.
11.
Rizzo, P. and Lanza di Scalea, F. (2007). Wavelet-based unsupervised and supervised learning algorithms for ultrasonic structural monitoring of waveguides. In: Reece, P.L. (ed.), Progress in Smart Materials and Structures Research, Ch. 8, pp. 227-290, NOVA science publishers Inc., New York.
12.
Kundu, T. (2004). Ultrasonic Nondestructive Evaluation: Engineering and Biological Material, CRC Press, Florida, ISBN 0849314623.
13.
Buck, O., Morris, W.L. and Richardson, J.M. (1978). Acoustic harmonic generation at unbonded interfaces and fatigue cracks. Appl. Phys. Lett. , 33(5), 371-373.
14.
Richardson, M. (1979). Harmonic generation at an unbonded interface. I. Planar interface between semi-infinite elastic media . Int. J. Eng. Sci., 17, 73-75.
15.
Morris, W.L. , Buck, O. and Inman, R.V. (1979). Acoustic harmonic generation due to fatigue damage in high-strength aluminum. J. Appl. Phys., 50(11), 6737-6741.
16.
Kawashima, K. , Omote, R., Ito, T., Fujita, H. and Shima, T. (2002). Nonlinear acoustic response through minute surface cracks: FEM simulation and experimentation. Ultrasonics, 40(1-8), 611-615.
17.
Kogl, M., Hurlebaus, S. and Gaul, L. (2004). Finite element simulation of non-destructive damage detection with higher harmonics. NDT & E International , 37(3), 195-205.
18.
Hillis, A.J., Neild, S.A., Drinkwater, B.W. and Wilcox, P.D. (2006). Global crack detection using bispectral analysis . Proceedings of the Royal Society A, 462, 1515-1530.
19.
Rivola, A. and White, P.R. (1998). Bispectral analysis of the biharmonic oscillator with application to the detection of fatigue cracks. Journal of Sound and Vibration, 216(5), 889-910.
20.
Donskoy, D.M. and Sutin, A.M. (1998). Vibro-acoustic modulation nondestructive evaluation technique. Journal of Intelligent Material Systems and Structures, 9, 765-771.
21.
Parsons, Z. and Staszewski, W.J. (2006). Nonlinear acoustics with low-profile piezoceramic excitation for crack detection in metallic structures . Smart Materials and Structures, 15, 1110-1118.
22.
Lee, Y.L., Pan, J., Hathaway, R. and Barkey, M. (2005). Fatigue damage theories, Fatigue Testing and Analysis, 57, Elsevier Inc., Boston.
23.
Friswell, M.I. and Penny, J.E.T. (2002). Crack modeling for structural health monitoring. Structural Health Monitoring , 1(2), 139-148.
24.
Pecorari, C. (2003). Nonlinear interaction of plane ultrasonic waves with an interface between rough surfaces in contact . J. Acoust. Soc. Am., 113(6), 3065-3072.
25.
Worden, K. and Tomlinson, G.R. (2001). Nonlinearity in Structural Dynamics, p. 49, and 55, Institute of Physics Publishing, Bristol and Philadelphia.
26.
Greenwood, A. and Williamson, J.B.P. (1966). Contact of nominally flat surfaces. Proc. R. Soc. London, Ser. A, 295, 300-319.
