Modal sensing of circular cylindrical shells using segmented piezoelectric elements

In this computational study, we use thin piezoelectric films as sensors to detect vibration of circular cylindrical shells. Rather than using complicated sensor shapes for modal filtering, we use simple rectangular shapes and leave the measurement filtering to full order modal observers. Simulations indicate that decreasing the magnitude of the real part of the observer gain leads to slower convergence but to the desired mode. Larger values lead to faster convergence but to the actual sensor measurements, indicating that little signal filtering had time to occur. Increasing the number of sensors also improves observer performance provided that they are placed intelligently on the shell. If a sensor cannot adequately detect the mode which it was intended to sense, sensor output cancellation may affect the behavior of all modal observers. The contribution of different mode types within different frequency bands is also investigated, as well as the determination of an adequate number of vibrational modes to include in the simulations.