Enhanced flexural wave sensing by adaptive gradient-index metamaterials.

Y Y Chen,R Zhu,G L Huang,M V Barnhart

doi:10.1038/srep35048

Abstract

Increasing sensitivity and signal to noise ratios of conventional wave sensors is an interesting topic in structural health monitoring, medical imaging, aerospace and nuclear instrumentation. Here, we report the concept of a gradient piezoelectric self-sensing system by integrating shunting circuitry into conventional sensors. By tuning circuit elements properly, both the quality and quantity of the flexural wave measurement data can be significantly increased for new adaptive sensing applications. Through analytical, numerical and experimental studies, we demonstrate that a metamaterial-based sensing system (MBSS) with gradient bending stiffness can be designed by connecting gradient negative capacitance circuits to an array of piezoelectric patches (sensors). Furthermore, we demonstrate that the proposed system can achieve more than two orders of magnitude amplification of flexural wave signals to overcome the detection limit. This research encompasses fundamental advancements in the MBSS with improved performance and functionalities, and will yield significant advances for a range of applications.

Highlights

Elastic wave sensors play a crucial role in the detection of elastic wave signals for measuring and imaging structural dynamic behaviors in order to ensure reliability and detect possible damage[1,2,3,4]
Lightweight piezo-patches periodically shunted by passive inductance-resistance (LR) electrical circuits can produce locally resonant band gaps and piezo-patches with semi-active negative capacitances (NCs) allow tunable band gaps or wave-guiding over desired broadband frequency ranges through the use of integrated active components in circuits[33,34,35,36]
To illustrate the enhanced flexural wave sensing in the metamaterial device, a transient flexural wave signal overwhelmed by noise is successfully recovered to overcome the detection limit of conventional piezoelectric sensors

Summary

Introduction

Elastic (mechanical) wave sensors play a crucial role in the detection of elastic wave signals for measuring and imaging structural dynamic behaviors in order to ensure reliability and detect possible damage[1,2,3,4]. In stark contrast to the tremendous progress in acoustic metamaterials, decelerating, trapping and spectrum-splitting of elastic waves by using elastic metamaterials has not yet been realized due to the fact that there is still a lack of a feasible and tunable meta-structure with strong gradient index (GRIN) and wave dispersion properties These abilities are crucial in many applications ranging from elastic wave spatial focusing to frequency selection in elastic wave detection and imaging. Adaptive structural systems with integrated piezoelectric shunt circuits have been proven as a promising method to achieve mechanical vibration/wave attenuation and control by electrically tuning the dynamic stiffness, mass density and impedance[20,21,22,23,24,25,26,27,28,29,30,31,32] This technique is convenient because the transducer acts as both a sensor and an actuator but with a reduced weight. To illustrate the enhanced flexural wave sensing in the metamaterial device, a transient flexural wave signal overwhelmed by noise is successfully recovered to overcome the detection limit of conventional piezoelectric sensors

Methods

Results

Conclusion