Guided-wave (GW) approaches have shown potential in various initiallaboratory demonstrations as a solution to structural healthmonitoring (SHM) for damage prognosis. This thesis starts with anintroduction to and a detailed survey of this field. Some criticalareas where further research was required and those that were chosento be addressed herein are highlighted. Those were modeling, designguidelines, signal processing and effects of elevated temperature.Three-dimensional elasticity-based models for GW excitation andsensing by finite dimensional surface-bonded piezoelectric wafertransducers and anisotropic piezocomposites are developed for variousconfigurations in isotropic structures. The validity of these modelsis extensively examined in numerical simulations and experiments.These models and other ideas are then exploited to furnish a set ofdesign guidelines for the excitation signal and transducers in GW SHMsystems. A novel signal processing algorithm based on chirpletmatching pursuits and mode identification for pulse-echo GW SHM isproposed. The potential of the algorithm to automatically resolve andidentify overlapping, multimodal reflections is discussed and exploredwith numerical simulations and experiments. Next, the effects ofelevated temperature as expected in internal spacecraft structures onGW transduction and propagation are explored based on data from theliterature incorporated into the developed models. Results from themodel are compared with experiments. The feasibility of damagecharacterization at elevated temperatures is also investigated. Anextension of the modeling effort for GW excitation byfinite-dimensional piezoelectric wafer transducers to composite platesis also proposed and verified by numerical simulations. At the end,future directions for research to make this technology more easilydeployable in field applications are suggested.
PDF
download
878987797
028-85220240
