Defect Detection in Carbon-Fiber Composites using Lamb-Wave Tomographic Methods

Lamb-wave tomography (LWT) offers a powerful nondestructive technique for the health assessment of large structures as their propagation properties depend on the thickness and the mechanical properties of the material. Development of a fast and accurate algorithm for defect detection is of paramount importance in any structural-health-monitoring (SHM) system. The present study explores the prospects of LWT as a SHM technique with an accent on developing a suitable algorithm for real-time inspection. Projection data is collected by electronically scanning an array of ultrasonic sensors arranged in a modified cross-hole geometry. The data thus collected is investigated to extract energy profile of the traveling waves. Multiplicative algebraic reconstruction technique (MART) algorithms are used as a tool for tomographic reconstruction from a set of multiple independent measurements. The performance of algorithms is evaluated from the point of view of the cost of algorithm, achievable resolution, and accuracy of results. Experimental results show that MART is capable of characterizing defects in thin isotropic and composite plates within a reasonable error band (  26% normalized,  2.6 RMS) and is suitable for application to LWT of large structures such as aircraft skins.

1. F. K. Chang. Proceedings of the Second International Workshop on Structural Health Monitoring, Stanford University, Stanford, CA (1999). 2. W. G. Schwarz, M. E. Read, M. J. Kremer, M. K. Hinders, and B. T. Smith. SPIE Conference on Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware III. SPIE 3586:292 (1999). 3. A. Viktorov. Rayleigh and Lamb Waves. Plenum Press, New York (1970). 4. J. L. Rose. Ultrasonics Waves in Solid Media. Cambridge University Press, Cambridge (1999). 5. J. Krautkramer and H. Krautkramer. Ultrasonic Testing of Materials. Springer-Verlag, Heidelberg, Germany (1983). 6. D. N. Alleyne and P. Cawley. Proceedings of the Institution of Mechanical Engineers, Pt. E. Journal of Process Mechanical Engineering 210:217 (1996). 7. A. C. Kak and Malcolm Slaney. Principles of Computerized Tomographic Imaging. IEEE Press (1998). 8. G. T. Herman. Image Reconstruction from Projections: The Fundamentals of Computerized Tomography. Academic Press, New York (1980). 9. P. Subbarao, P. Munshi, and K. Muralidhar. NDT & E International 30:359 (1997). 10. R. Gordon, R. Bender, and G. T. Herman. J. Theo. Biol. 29:471 (1970). 11. R. Gordon and G. T. Herman. Int. Rev. Cytol. 38:111 (1974). 12. A. Lent. Proc. SPIE Image Analysis and Evaluation, R. Shaw (ed.), 249 (1977). 13. A. Curtis. Cambridge Research, SEG Expanded Abstracts, 17:797, Soc. of Exploration Geophysicists, Tulsa, OK (1998). 14. E. V. Malyarenko and M. K. Hinders. J. Acoustical Society of America 108:1631 (2000). 15. MATLAB documentation available at 16. S. Khare. Lamb Wave Tomography for Structural Health Monitoring of Aircraft Systems, Indian Institute of Technology, M.Tech. Thesis (2005). 17. N. Guo and P. Cawley. NDT & E International 29:247 (1996).
Usage Shares
Total Views
10 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage