A semi-analytical approach to design of a transducer for selective wave generation

Abstract

Piezoelectric transducers are extensively employed for elastic waves–based structural health monitoring and non-destructive testing systems. In those systems, multimodal, dispersive guided waves are generated and acquired through transducers attached to, or embedded into, a structure. Although, guided waves are potentially attractive due to multiple features that can be possibly used for damage detection, there exists significant complexity associated with data analysis. Proper transducer design and/or selection can substantially facilitate damage detection, evaluation and localization through selective wave generation and/or acquisition. This article discusses a topology optimization technique as a prerequisite for transducers design. A semi-analytical approach for wavefield prediction is presented. The method consists in combining analytically calculated spectral characteristics – that is, dispersion and excitability curves – of a medium, and a numerical representation of a transducer, for prediction of the resulting displacement field generated upon application of a time- and space-varying stress field. Furthermore, the model is employed in an optimization strategy, where transducer’s topology is arranged to achieve selective excitation of a guided wave mode.