Impact Monitoring of Smart Composite Laminates Using Neural Network and Wavelet Analysis

Abstract

Low-velocity impact damage is a major concern in the design of structures made of advanced laminated composites, because such damage is mostly hidden inside the laminates and cannot be detected by visual inspection. It is necessary to develop the impact monitoring techniques providing on-line diagnostics of smart composite structures susceptible to impacts. In this paper, we discuss the process for impact location detection in which the generated acoustic signals are detected by PZT using the improved neural network paradigms. To improve the accuracy and reliability of a neural network based impact identification method, the Levenberg-Marquardt algorithm and the generalization methods were applied. This study concentrates not only on the determination of the location of impacts from sensor data, but also the implementation of time-frequency analysis such as the Wavelet Transform (WT) to measure the characteristic frequencies of acoustic emission waves for the determination of the occurrence and the estimation of impact damage.

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References

Alkhaidy, A. , M. Noori , Z. Hou , S. Yamamoto , A. Masuda and A. Sone . 1997. “Health Monitoring Systems of Linear Structures Using Wavelet Analysis,” Proceedings of the International Workshop on Structural Health Monitoring, 1:164-175.

Chang, F. K. , 1995. “Built-in Damage Diagnostics for Composite Structures,” Proceedings of ICCM-10, V:283-289.

Choi, I. H. 1994. “Response and Damage of Composite Laminates Subjected to Low-velocity Impact,” Ph.D. Thesis in KAIST: 48-99.

Choi, I. H. and C. S. Hong . 1994. “Low-velocity Impact Response of Composite Laminates Considering Higher-order Shear Deformation and Large Deflection,” Mechanics of Composite Materials and Structures, 1:157-170.

Choi, K. and F. K. Chang , 1996. “Identification of Impact Force and Location Using Distributed Sensors,” AIAA Journal, 34(1):136-142.

Demuth, H. and M. Beale . 1998. Neural Network Toolbox, The Math Works, Inc.

Gunther, M. F. , K. A. Murphy and R. O. Claus et al. , 1992. “Fiber Optic Impact Detection and Location System Embedded in a Composite Material,” Proceedings of SPIE on Fiber Optic Smart Structures and Skins V, 1798:262-269.

Hagan, M. T. and M. Menhaj , 1994, “Training Feedforward Networks with the Marquardt Algorithm,” IEEE Transactions on Neural Networks, 5(6):989-993.

Harrison, G. A. , I. Koren , M. Lewis and F. J. Taylor , 1998, “Application of Wavelet and Wigner Analysis to Gas Turbine Vibration Signal Processing,” Proceedings of SPIE on Wavelet Application, 3391:490-501.

10.

Haykin, S. 1994. Neural Networks, Macmillan College Publishing Company.

11.

Jones, R. T. , J. S. Sirkis and E. J. Frebele . 1997. “Detection of Impact Location and Magnitude for Isotropic Plates Using Neural Networks,” Journal of Intelligent Material Systems and Structures, 7(1):90-99.

12.

Kudva, J. N. , C. Marantidis and J. Gentry . 1993. “Smart Structures Concepts for Aircraft Structural Health Monitoring,” Proceedings of SPIE on Smart Structures and Materials, 1917:974-981.

13.

Lichtenwalner, P. F. , E. V. White and E. W. Baumann . 1998. “Information Processing for Aerospace Structural Health Monitoring,” Proceedings of SPIE on Smart Structures and Materials, 3326:406-417.

14.

Loh, C. H. and Z. K. Lee. 1997. “Substructural Identification of a Bridge—A FFT Based Spectral Analysis,” Proceedings of the International Workshop on Structural Health Monitoring, 1:111-121.

15.

Maseras-Gutierrez, M. A. , W. J. Staszewski , M. S. Found and K. Worden , 1998. “Detection of impacts in composite materials using piezoceramic sensors and neural networks,” Proceedings of SPIE on Smart Structures and Materials, 3329: 491-497.

16.

Misiti, M. , Y. Misiti , G. Oppenheim and J. M. Poggi . 1996. Wavelet Tool-box, The Math Works, Inc.

17.

Newland, D. E. 1993. An Introduction to Random Vibrations, Spectral and Wavelet Analysis, 3rd ed., Longman Group Lim.

18.

Okafor, A. C. , K. Chadrashekhara and Y. P. Jiang . 1996. “Delamination Prediction in Composite Beams with Built-in Piezoelectric Devices Using Modal Analysis and Neural Network,” Smart Materials and Structures, 5(3):338-347.

19.

Sanders, G. W. and K. Chandrashekhara et al. 1997. “Fiber Optic Vibration Sensing and Neural Networks Methods for Prediction of Composite Beam Delamination,” Proceedings of SPIE on Smart Structures and Materials, 3041:858-867.

20.

Schindler, P. M. , R. G. May and R. O. Claus . 1995. “Location of Impacts on Composite Panels by Embedded Fiber Optic Sensor and Neural Network Processing,” Proceedings of SPIE on Smart Structures and Materials, 2444:481-489.

21.

Spillman Jr., W. B. , J. S. Sirkis and P. T. Gardiner . 1996. “Smart Materials and Structures; What are they?,” Smart Materials and Structures, 5(3):247-254.

22.

Wang, W. J. and P. D. McFadden , 1996, “Application of Wavelets to Gear-box Vibration Signals for Fault Detection,” Journal of Sound and Vibration, 192(5):927-939.