Phononic structures for ultra-precision sensing

Sabiju Valiya Valappil (PhD candidate), Alejandro M. Arag√≥n (supervisor), and Fred van Keulen (supervisor)

Phononic crystals (PnCs) and acoustic metamaterials (AMMs) are architectured structures that show unusual dynamic characteristics due to the presence of band gaps (BGs), which prevent the propagation of mechanical waves in their corresponding frequency range. The two mechanisms of BG formation are Bragg scattering (due to destructive interference at material interfaces) and Mie scattering (resonance frequency of resonators). PnCs and AMMs are used in various applications such as vibration isolation, energy harvesting, acoustic cloaking, and frequency steering among others. In this project, we focus on the wave rejection/steering aspect of PnCs and AMMs.

Objectives

To use PnCs and AMMs for removing/redirecting unwanted waves to improve the accuracy of flow measuring systems.

Methods

Analytical and numerical methods (e.g, spectral element method, finite element method, etc.,) to analyze and design periodic unit cells (PUCs) and finite waveguides of PnCs and AMMs. Realize these designs by using additive manufacturing and perform high-precision experiments for verification.

The figure shows schematic of a 1D AMM waveguide with its PUC followed by its band structure and transmissibility. Sweeping the wave vector along the vertices of the IBZ (length of PUC in this case) provides us the band structure which relates frequency to the wave vector. Band gap frequency range shown in (a) is the range of frequency where no waves propagate. Frequency sweep of the finite AMM waveguide provides transmissibility (shown in (b)), which shows the reduction in amplitude of input signal for a particular number of PUCs.

 

Partners involved 

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