Damage Identification in Structures with Lamb Waves and Optimal Sensor Layout Designing

Keshavarz Motamed, Pouyan | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50204 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Abedian, Ali
  7. Abstract:
  8. This study presents the best layout with optimal number of sensors for an arbitrary monitoring area based on reference free damage detection and localization. In recent years, damage detection approaches with the concept of instantaneous baseline measurements in Structural Health Monitoring (SHM) with lamb wave propagation are being developed. An array of spars transducers is obligatory in SHM with lamb wave propagation, so that designing the best one is a concern for many researchers. To obtain the best sensors layout, damage localization process should be done for all definable sensors layouts in many different crack positions. Obviously, doing this seems not practical as wave propagation using finite element modeling is considerably time consuming. To overcome this in the present study, a database of continuous wavelet transform (CWT) based signal features is developed from interaction of wave signals with a specific crack for different sensing paths and different crack positions and orientations. Therefore damage localization can be done for any crack positions in any sensors layouts by interpolating the database’s results. The validation of the method is done by comparing damage localization based on database’s results and simulating the wave propagation in performing finite element modeling for three sensors layouts. Now many different sensors layouts according to the monitoring area are defined. The localization process based on the database’s data is done for the crack in many different positions in sensor layouts. Then the best layout with optimal number of sensors is obtained according to minimum distances between the cracks and the points with the highest probability of damage coming from damage localization
  9. Keywords:
  10. Structural Health Monitoring ; Damage Detection ; Piezoelectric Transducers ; Probabilistic Based Diagnosis Imaging (PDI) ; Lamb Wave Power ; Wave Propagation ; Optimal Sensors Loyout Designing

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