Fourier-based Design of Acoustic Transducers
Mechanical and Aerospace Engineering
Department Seminar Series
Matteo Carrara
School of Aerospace Engineering
Georgia Institute of Technology
The work presented investigates novel transducers implementations that take advantage of directional sensing and generation of acoustic waves by exploiting a Fourier-based design methodology. The objectives are to conceive and design innovative piezoelectric arrangements by specifying their electrode patterns in the Fourier domain. Design procedures are outlined and tailored to specific Structural Health Monitoring (SHM) and energy harvesting applications. The theoretical frameworks tailored to the specific applications will be presented alongside numerical and experimental validation in support of the devices development.
When targeting SHM applications, the work contributes to the formulation of (i) Frequency Steered Acoustic Transducers (FSATs), and (ii) the Acoustic Wave Rosette. FSATs are devices that can direct Guided Waves (GW) energy in specified directions without the need for individual element control. They are characterized by a spatial arrangement of the piezoelectric material, which leads to frequency-dependent directionality. The resulting transducers can be employed both for directional sensing and generation of guided waves, without relying on phasing and control of a large number of channels. The AWR, similarly to the FSATs class, is characterized by an internal patterning whose bi-dimensional Fourier representation features maxima at specific directions. The unique features of the AWR is its ability to act a multi-band spatial filter suitable for strain sensing applications by monitoring peaks shift in the wavenumber domain triggered by the deformation state in the underlying structure.
In addition, for energy harvesting matters, the work explores efficient transformation of broadband GW energy into low-power electricity using patterned polymer piezoelectrics integrated with an Elliptical Acoustic Mirror (EAM) configuration. In particular, the mirror under consideration features a semi-elliptical continuous mirror with a rectangular arrangement of harvesting material overlapping the geometrical focus of the mirror.
Biosketch
Matteo received his bachelor and master degrees in Aeronautical Engineering from Politecnico di Milano in 2008 and 2011, respectively, and a second master in Aerospace Engineering from Georgia Tech in 2014. He is currently working on his Ph.D. thesis as a graduate research assistant in the School of Aerospace Engineering at Georgia Tech, under the supervision of Dr. Massimo Ruzzene. His interests lie in the broad fields of structural dynamics and wave propagation, with particular emphasis on the design of Fourier-based acoustic transducers for advanced structural health monitoring schemes, metamaterial-inspired applications and design of optimal sensing material distribution for structure-born wave energy harvesting, and multi-physics FE simulations of wave propagation in isotropic and anisotropic media. He is a member ASME, SPIE, AHS, and AIAA, and an invited reviewer for Applied Physics Letters, the International Journal of Smart and Nano Materials, the Journal of Intelligent Material Systems and Structures, and the Journal of Dynamic Systems, Measurement and Control.