- Air Force Office of Scientific Research
- Prof. Hyonny Kim, UCSD
- Profs. Ajovalasit and D’Acquisto, University of Palermo Italy
To develop a wave-based technique for (1) impact location, (2) impact force identification (force time history), and (3) discrimination of “damaging impacts” from “non-damaging impacts” on complex aerospace panels
Conventional time-of-flight triangulation of Acoustic Emission (AE) sources leads to inaccurate impact/damage location results when the structure is complex in either material properties (e.g. anisotropic, composite), or in geometry (e.g. multilayers, tapered sections). In these cases, generally, the acoustic wave speed is not constant. In this project we are developing the Piezoelectric Rosette technique to detect the source of an AE (impact or active damage) in complex aerospace panels. The Piezoelectric Rosette technique does not require prior knowledge of material properties (i.e. wave speeds). We are using the flexible Macro-Fiber Composite (MFC) piezoelectric transducer patches in the Rosettes for greater robustness against impacts compared to monolithic PZT disks. We have demonstrated the MFC Piezoelectric Rosette technique for accurate AE source location in variety of Aluminum and composite CFRP panels, both stiffened and unstiffened, and subjected to both low-velocity impacts (hammer) and high-velocity impacts (ice and wood projectiles lunched from a gas-gun at speeds up to 170 m/sec).
In addition to impact location, we have developed a wave-based inverse identification algorithm for determining the time history of the impact force magnitude (Force Identification). The method is based on inverting a Semi-Analytical Finite Element Analysis-based forced solution for the panel and minimizing the difference between predicted and measured responses. Our identification method was able to match well the experimentally-measured impact force histories from hammers and also predict the high-velocity impact force histories from wood and ice projectiles lunched from a gas-gun at speeds up to 170 m/sec. Using this method, accurate impact force identification has been performed on both aluminum and CFRP composite aerospace panels.
A third outcome of this work is the discrimination of “damaging impacts” from “non-damaging impacts” from the waveforms recorded in the panels (Impact Classification). Once implemented in an SHM system, such impact classification ability will help making the most appropriate decision such as follow-up NDE inspections. Our impact classification metric is based on the frequency content of the generated AE waves and statistical pattern recognition algorithms. Successful impact classification using this method has been conducted on both Aluminum and CFRP panels, and confirmed by ultrasonic C-scans performed on the panels following the impacts.
C. Nucera, S. White, Z. M. Chen, H. Kim, and F. Lanza di Scalea, “Impact Monitoring In Stiffened Composite Aerospace Panels By Wave Propagation,” Structural Health Monitoring International Journal, in review, 2014.
Kijanka, P., Manohar, A., Lanza di Scalea, F. and Staszewski, W., “Damage Location by Ultrasonic Lamb Waves and Piezoelectric Rosettes”, Journal of Intelligent Materials Systems and Structures, in press, 2014.
Kijanka, P., Manohar, A., Lanza di Scalea, F. and Staszewski, W., “Damage Location By Ultrasonic Lamb Waves And Piezoelectric Rosettes,” Proceedings of SPIE (International Society for Optical Engineering) Smart Structures/NDE Annual International Symposium – Health Monitoring of Structural and Biological Systems, T. Kundu, ed., San Diego, CA, March 9-13, Vol. 9064, pp. 9064221 – 90642213, 2014.
Nucera, C., White, S., Kim, H., and Lanza di Scalea, F., “Piezoelectric Rosettes For Acoustic Source Location In Composite Structures: Results From “Blunt” Impact Tests,” Structural Health Monitoring 2013 – A Roadmap to Intelligent Structures – Proceeding of the 9th Intl Workshop on Structural Health Monitoring, F-K. Chang, ed., Stanford University, pp. 2635-2642, Sept. 10-12, 2013.
Lanza di Scalea, F., Kim, H., White, S., Chen, Z., Salamone, S., and Bartoli, I., “Impact Monitoring In Aerospace Panels Via Piezoelectric Rosettes,” Composite Materials and Joining Technologies for Composites, Vol. 7, E. Patterson et al. (eds.), 7 pgs., 2012.
Lanza di Scalea, F., Kim, H., Chen, Zhi, Salamone, S., and Bartoli, I., “Impact Monitoring In Aerospace Panels Via Piezoelectric Rosettes,” Proceedings of the SEM XII International Congress and Exposition, Costa Mesa, CA, June 11-14, 2012.
Lanza di Scalea, F., Salamone, S., Bartoli, I., Kim, H., and Rhymer, J., “Location and Identification of Impact Forces in Composite Aerospace Panels,” Proceedings of the 40th National Conference of the Italian Association for Stress Analysis (AIAS), Palermo, Italy, September 7-10, 2011.
Salamone, S., Bartoli, I., Di Leo, P., Lanza di Scalea, F., Ajovalasit, A., D’Acquisto, L., Rhymer, J., and Kim, H., “High-velocity Impact Location on Aircraft Panels Using Macro-fiber Composite Piezoelectric Rosettes,” Journal of Intelligent Materials Systems and Structures, 21(9), pp. 887-896, 2010.
Bartoli, I., Salamone, S., Lanza di Scalea, F., Rhymer, J. and Kim, H., “Impact Force Identification on Aerospace Panels,” Proceedings of the ASME International Mechanical Engineering Congress, Vancouver, Canada, November 12-18, 2010.
Bartoli, I., Salamone, S., Mezzanotte, M., Lanza di Scalea, F., Kim, H., Rhymer, J., “Impact Force Identification on Isotropic and Composite Panels,” Proceedings of SPIE’s Smart Structures NDE Conference, Health Monitoring of Structural and Biological Systems IV (Vol. 7650), San Diego, CA, March 7-11, pp. 7650071-76500712, 2010.
Bartoli, I., Salamone, S., Di Leo, P., Mezzanotte, M., Lanza di Scalea, F., Kim, H., Rhymer, J., Phillips, R., Ajovalasit, A., and D’Acquisto, L., “Impact Force Identification and Location on Isotropic and Composite Panels,” Proceedings of the 7th International Workshop on Structural Health Monitoring, Stanford University, Stanford, CA, September 9-11, pp. 1902-1909, 2009.
Matt, H. and Lanza di Scalea, F., “Macro-fiber Composite Piezoelectric Rosettes for Acoustic Source Location in Complex Structures,” Smart Materials and Structures, Vol. 16(4), pp. 1489-1499, 2007.