[CCoE Notice] Ph.D. Thesis Defense: July 25th at 930a

[Grayson, Audrey A]

Development of Advanced Piezoceramics Based Structural Health Monitoring Methods for Applications In The Energy
Jiabiao Ruan
Committee Members: Dr. Gangbing Song (chair), Dr. Matthew Franchek, Dr. Yi-lung Mo (CIVE), Dr. Li Sun and Dr. Mo Li (CIVE)
Defense Location: Mechanical Engineering Large Conference Room
Defense Time: 9:30am-11:30am on July 25th

As the economic backbone of the United States, the energy industry has high demands for structural health monitoring of the facility and devices. However, lack of sensors and related methods pose challenges for the monitoring of different applications. This dissertation focused on the monitoring methods development based on piezoceramic transducers. Five energy industry applications were deployed with the developed methods for monitoring purposes.
This dissertation proposed Acoustic Emission (AE) passive sensing method and related AE clustering and classification methods, which used piezoceramic transducers as sensors only. AE methods were applied in the gate valve to monitor the valve's condition, especially the wear between the gate /seat contact surface. They were also utilized to detect the damages of wind turbine blades during destructive tests. The cluster and classification methods were able to distinguish the AE sources to provide more accurate information for the AE and structural health correlations.
With different piezoceamic transducers as actuators and sensors respectively, innovative active sensing methods including Time Reversal Method (TRM), Real-time Cross Correlation Method (RCCM), wavelet packet based damage index, and polar plot analysis were also proposed and developed for the applications of gate valve contact surface condition monitoring, lap bolted joint loosening detection, pipeline tapered thread connection loosening and wind turbine blade damage detection. The advantages of the related active sensing methods such as anti-noise and real time display ability of TRM and RCCM were demonstrated. For bolted joint loosening detection, a Hertzian contact based energy model was developed to correlate the tightness with impulse response energy. Polar plot offered additional phase information to provide more accurate indication of structural health then conventional energy method. Embedded in active sensing methods, synergetics were first adopted for fault detection of frame structure with multiple bolted joint loosening cases to deal with uncertainty, disturbance and insufficient data problems at a fast speed.
PZT impedance sensing method was also implemented to measure the local damages around the PZT transducers on wind turbine blade. The method utilized the same PZT transducer to be actuator as well as sensor and indicated the blade damages with the PZT's coupled electromechanical impedance.


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