Modelling the input–output behaviour of piezoelectric structural health monitoring systemsfor composite plates

Abstract

This paper investigates the input–output characteristics of structural health monitoringsystems for composite plates based on permanently attached piezoelectric transmitter andsensor elements. Using dynamic piezoelectricity theory and a multiple integral transformmethod to describe the propagating and scattered flexural waves an electro-mechanicalmodel for simulating the voltage input–output transfer function for circular piezoelectrictransmitters and sensors adhesively attached to an orthotropic composite plate isdeveloped. The method enables the characterization of all three physical processes, i.e.wave generation, wave propagation and wave reception. The influence of transducer, plateand attached electrical circuit characteristics on the voltage output behaviourof the system is examined through numerical calculations, both in frequencyand the time domain. The results show that the input–output behaviour of thesystem is not properly predicted by the transducers’ properties alone. Couplingeffects between the transducers and the tested structure have to be taken intoaccount, and adding backing materials to the piezoelectric elements can significantlyimprove the sensitivity of the system. It is shown that in order to achieve maximumsensitivity, particular piezoelectric transmitters and sensors need to be designedaccording to the structure to be monitored and the specific frequency regime ofinterest.