ABSTRACT
Distributed sensors are shaped sensors which are bonded to the surface of a structure and are continuous over the length and the breadth of the structure. They are designed on the basis of the orthogonality principle of the modes of vibration of a structure. Distributed sensors are designed to monitor specific modes of vibration of the structure and are usually made of polyvinylidene fluoride (PVDF) piezoelectric polymer films. In this paper, PVDF shaped sensors are designed for monitoring the first and the second modes of vibration of a simply supported beam. The design principle for achieving the optimal sensor shape for a particular mode of vibration is based on making the sensor width zero at locations along the length of the beam where the strain is zero. Conversely, the sensor width is maximum where the strain in the beam is maximum for the particular mode of vibration. The vibration responses of the beam as measured by the distributed sensors are compared with the measured vibration responses using an accelerometer. It is shown that by dividing a classical PVDF shaped sensor for mode 1 into two halves, the sensor can be used to monitor modes I and 2 of the flexural vibration of the beam.
