Smart Piezoelectric Sensors Research Articles

Deep learning of electromechanical impedance for concrete structural damage identification using 1-D convolutional neural networks

Common damages in concrete materials and structures are usually in small sizes at initial stage, which induce small stiffness and mass loss being difficult to evaluate severity level merely depending on traditional electromechanical admittance (EMA, inverse of impedance) technique. In fact, several state-of-the-art computerized techniques have been incorporated with the EMA for automated evaluation of concrete damages. However, complicated data preprocessing still limits the efficiency of these techniques in terms of accuracy and computational cost. To this end, this paper proposed a novel deep learning approach using one-dimensional (1-D) convolutional neural networks (CNNs) for exploiting the raw EMA signatures to automatically identify tiny damages in concrete structures, which eliminated tedious data preprocessing for network training and testing. Two independent EMA databases measured by smart piezoelectric sensors were established based on proof-of-concept experiment of slight/severe mass-loss damage detection on a concrete cube, as well as practical application of bolt-looseness identification on a full-scaled shield tunnel segment assembled structure. For both tests, effect of varied dimensions of input data on the efficiency of CNN models were evaluated as well. The well-trained CNN model perfectly quantified the severity degrees of mass-loss and bolt-looseness damages, which demonstrated significant superiority than traditional back propagation neural network and the model with less dimensions of input data exhibited higher accuracy. Delightful results in this work potentially provided a potential paradigm of EMA data-driven tiny damage identification for real-life concrete infrastructures.

Ultra-sensitive flexible piezoelectric energy harvesters inspired by pine branches for detection

Realization of self-powered sensing devices has received substantial attention employing flexible piezoelectric energy harvesters (PEH). For effective implement, robust sensing and response capability to external mechanical load are demanded for PEH, which has been challenging. Here, flexible and ultra-sensitive PEH filled with pine-branch-inspired three-dimensional TiO2@polydopamine@Ag (3D TPA) fillers are proposed. Benefitting from the bioinspired structure design, the PEH device with incredible piezoelectric characteristics combining measurable output voltage and power density ( ~ 100 V and ~ 184.06 μW cm−2) contributes to reliable power source supply for sustainably drive electronic devices. Notably, the PEH device could be considered as piezoelectric sensors with ultra-sensitive sensing performances comprising high sensitivity (46.2 V N−1 and 6.64 μA N−1), low detection threshold (10 mg) and fast response time (1 ms) for detecting dropped tiny objects. The extraordinary piezoelectric outputs enhancement is put down to the multiple coupling induced by the 3D TPA, including improvement of load-transfer efficiency and poling electric field, which has been confirmed by experiment results and theoretical simulations. This work opens a novel insight to access 3D fillers and has a profound influence on the rational preparation of ultra-sensitive PEH for potential application in smart piezoelectric sensors.

Two-Dimensional Layered Perovskite Ferroelectric with Giant Piezoelectric Voltage Coefficient.

Piezoelectric sensors that can work under various conditions with superior performance are highly desirable with the arrival of the Internet of Things. For practical applications, a large piezoelectric voltage coefficient g and a high Curie temperature Tc are critical to the performance of piezoelectric sensors. Here, we report a two-dimensional perovskite ferroelectric (4-aminotetrahydropyran)2PbBr4 [(ATHP)2PbBr4] with a saturated polarization of 5.6 μC cm-2, high Tc of 503 K [above that of BaTiO3 (BTO, 393 K)], and extremely large g33 of 660.3 × 10-3 V m N-1 [much beyond that of Pb(Zr,Ti)O3 (PZT) ceramics (20 to 40 × 10-3 V m N-1), more than 2 times higher than that of poly(vinylidene fluoride) (PVDF, about 286.7 × 10-3 V m N-1)]. Combined with the advantages of molecular ferroelectrics, such as light weight, easy and environmentally friendly processing, and mechanical flexibility, (ATHP)2PbBr4 would be a competitive candidate for next-generation smart piezoelectric sensors in flexible devices, soft robotics, and biomedical devices.

Exploratory study on durability of concrete structures by using smart piezoelectric sensors

Abstract The objective of the study is to identify the possibilities of utilizing the quarry dust in concrete to obtain the improved strength and durability properties of concrete during sulphate attack by using smart piezoelectric sensor. In the present study the addition of quarry dust as alternative for natural sand and partial replacement for cement with GGBS has been investigated for the durability properties of concrete. Mechanical properties of conventional concrete and partially replaced GGBS concrete were evaluated. The GGBS incorporated concrete strength was evaluated and the comparison between mechanical properties of GGBS incorporated concrete and ordinary Portland cement concrete was made. Sensors were used for monitoring corrosion of reinforcement during sulphate attack in both cases.

Investigations on effectiveness of embedded PZT patches at varying orientations for monitoring concrete hydration using EMI technique

The electro-mechanical impedance (EMI) technique has already been established to be an effective technique for detecting incipient damages in engineering structures including reinforced concrete (RC) using smart piezo-electric sensors. Its effectiveness in monitoring the hydration of concrete, using surface bonded and embedded lead zirconium titanate (PZT) patches has also been investigated well. However, the influence of patch orientation while embedding them in concrete is still unexplored. The present study investigates the effectiveness of the EMI technique using PZT patches embedded at different orientations (here, 0°, 45° and 90°) with the axis of the structure, while monitoring the hydration of a real-life prototype RC beam. Further, the effectiveness of the PZT patches in monitoring the strength gain in concrete is investigated. It is observed that the PZT patch placed in the inclined orientation (45°) least efficient in capturing the progressive changes of hydration in the concrete in comparison to the other two orientations. The EMI technique showed best results when PZT patch was placed in horizontal position (0°) with the longitudinal axis of the beam.

Experimental investigations in embedded sensing of composite components in aerospace vehicles

This paper summarizes the experimental investigations for smart embedded sensing in rotorcraft composite components. The overall objective of this effort was to develop smart embedded sensor technologies for condition based maintenance (CBM) for composite components in army rotorcraft. This paper presents the results of experimental investigations related to development and maturation of different types of embedded sensing solutions for structural health monitoring of composite components including Fiber Bragg Grating (FBG) sensors, phased and discrete piezoelectric sensor arrays. A discussion is provided relative to embedment of optical fibers into composites, and the results from embedded FBG sensors in a rotorcraft flexbeam subcomponent test specimen with seeded delamination subjected to dynamic loading. Likewise, results are analyzed of surface mounted phased array and embedded smart piezoelectric sensors in the flexbeam subcomponent test specimen with embedded delamination, subjected to fatigue cyclic loading. The paper also summarizes the lessons learned from efforts to nucleate and propagate delamination within composite components under dynamic cyclic loading.