Continuous Real-Time State Monitoring in Highly Dynamic Environments
[Technical Report, Final Report]
TENNESSEE TECHNOLOGICAL UNIVERSITY
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The overall goal of this research is to develop continuous, real-time sensing capability for determining the state of a dynamic structure on the microsecond to millisecond timescale using piezoelectric impedance-based SHM concepts coupled with Real-Time FPGA hardware and advanced signal processing. To this end we have experimentally verified an optimized finite element model of piezoelectric impedance. Results of this numerical modeling effort have revealed some sensitivity to state change in the first thickness mode in the approx. 1-3 MHz range. Next, our most significant research contribution is the development of a novel, resource-efficient impedance measurement technique termed the multi-narrowband excitation approach. Multi-narrowband excitation utilizes the ability to generate custom excitation waveforms when using a DAQ-based impedance approach to 1 reduce the amount of data acquired to perform state detection, thereby 2 reducing the amount of time required to process the acquired data, to ultimately 3 realize improvements to the efficiency and speed of the state detection process. Evaluation of the technique has shown a 77 percent reduction in excitation time and a 94 percent reduction in excitation energy when compared to utilizing broadband chirp excitation. Finally, we have developed a continuous state monitoring system that utilizes a custom written LabVIEW interface to continuously monitor the state of a structure. Evaluation of the system on a non-optimized DAQ platform have shown detection times on the order of 20-200 ms. Further improvements are expected when combined with the real-time state monitoring architecture that we developed separately testing of which showed sensitivity in piezoelectric impedance up to 3 MHz.
- Electricity and Magnetism