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Investigation of Damage and Wearing Mechanism of Aircraft Structural Components

Tashi, Samaneh | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42736 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Abedian, Ali
  7. Abstract:
  8. Damage detection by Piezoelectric Wafer Active Sensors is one of the emerging efficient and dominant Structural Health Monitoring (SHM) methods. These sensors assess the health state of the structure due two strategies: a) near-field damage detection, b) far-field damage detection. The far-field damage detection is based on the high frequency Lamb wave propagation. As wave travels in a damaged structure, phase and amplitude of the wave will be changed. So comparison of the received signal from the pristine structure with damaged structure can give useful information about the health state of the structure. As PWAS is the essential part of this method, simulation and modeling of this sensors and their interaction with host structure, strongly affect the accuracy of results. Previous works have considered some certain areas of the host structure as a sensor and actuator. Then applied excitation to this equivalent actuator area and examined the mechanical response acquired at simulated sensor area. But due to using the coupled field elements, direct simulation of electro-mechanical interaction of the PWAS and the host structure was made possible. The electrical potential generated on the PWAS surface by the stimulation of elastic wave can be examined this FEM analysis. After verification of the FEM analysis with theoretical Time of Flight (TOF), capability of the S0 mode in crack detection was examined. Different length and angles of the crack modeled. Finally, by using the strain energy magnitude, the crack growth effect was defined among a damage index. Also the capability of wave propagation by piezoelectric wafer active sensors in corrosion damage detection was studied. A 100 KHz five count smoothed tone burst was excited at actuator. Received signals of the pristine and damaged structure were compared at different corrosion depth throughout a crossplot. This study, demonstrated that monitoring of the corrosion damage by PWAS is possible
  9. Keywords:
  10. Lamb Wave ; Structural Health Monitoring ; Finite Element Method ; Crack Detection ; Piezoelectric Wafer Active Sensor ; Corrosion Detection

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