We designed and analyzed a piezo-lens to focus flexural waves in thin plates. The piezo-lens comprises a host plate and piezoelectric patches bonded on the surfaces of the plate. The piezoelectric patches are shunted with negative capacitance circuits. The effective refractive indexes inside the piezo-lens are designed to fit a hyperbolic secant distribution by tuning the negative capacitance values. A homogenized model of piezo-mechanical system is adopted in the designing process of the piezo-lens. The wave focusing effect is studied by the finite element method. Numerical results show that the piezo-lens can focus flexural waves by bending their trajectories, and is effective in a large frequency band. The piezo-lens has the ability to focus flexural waves at different locations by tuning the shunting negative capacitance values. Potential applications of the piezo-lens include energy harvesting, SHM, etc.
Kaijun Yi and Manuel Collet, "Gradient-index based smart metacomposite for elastic wave focusing (Conference Presentation)," Proc. SPIE 10170, Health Monitoring of Structural and Biological Systems 2017, 101701M (Presented at SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: March 29, 2017; Published: 11 May 2017); https://doi.org/10.1117/12.2263342.5427850831001.
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Study of self-shadowing effect as a simple means to realize nanostructured thin films and layers with special attentions to birefringent obliquely deposited thin films and photo-luminescent porous silicon