Structural Health and Strain Monitoring Sensing through Fourier-Based Transducers.

The article reports on the design of a novel class of transducers for structural health monitoring and strain sensing designed using a Fourier-based approach. The design procedure formulates the problem considering an arbitrarily shaped distribution of the sensing surface. Interrogation of the sensors is based on the generation of guided and surface acoustic waves generated in the region surrounding the transducers. The representation of the distribution of the sensing material is analyzed and designed in the spatial Fourier domain, where the emission characteristics of the transducer in relation to the interrogating wave can be tailored to a specific application. For structural health monitoring, the sensing material distribution can be defined to provide the transducers with frequency-dependent directional properties, which can be employed as part of an interrogation scheme based on generation and processing of guided waves in the structure. For strain sensing, one-dimensional and two-dimensional grating configurations monitor frequency shifts of radiation associated to local straining of the gratings. These frequency shifts can be related to the local strain components, so that a rosette-like configuration can be implemented. The article illustrates the commonalities of the design procedure, which leads to novel Lamb wave and strain transducers, and suggests the potential integration of the two sensing modalities as a single device for health and usage monitoring of structural components. [ABSTRACT FROM PUBLISHER]