Development of piezoelectric strain gages for structural health monitoring applications

The strain monitoring capability of piezoelectric materials was experimentally studied. Patches and fibers were considered for this purpose. A piezoelectric stripe actuator was used to obtain the typical signal of patches. Two designs were considered for the piezoelectric fibers. The first one was a commercial energy harvesting device with long fibers. The ends of the fibers were loose. In contrast, we designed a small piezoelectric strain gage with short fibers. Fibers were attached to wires at two ends with conductive resin. The piezoelectric strip actuator, and commercial energy harvesting device were connected to digital oscilloscope directly. A charge amplifier was used to condition the signals of the small piezoelectric strain gage with short fibers. All the units were attached to a beam and excited at different frequencies to evaluate the characteristics of their signals.