In this study, the quantification of temperature effect on impedance monitoring via a PZT interface for prestressed tendon-anchorage is presented. Firstly, a PZT interface-based impedance monitoring technique is selected to monitor impedance signatures by predetermining sensitive frequency bands. An analytical model is designed to represent coupled dynamic responses of the PZT interface-tendon anchorage system. Secondly, experiments on a lab-scaled tendon anchorage are described. Impedance signatures are measured via the PZT interface for a series of temperature and prestress-force changes. Thirdly, temperature effects on measured impedance responses of the tendon anchorage are estimated by quantifying relative changes in impedance features (such as RMSD and CCD indices) induced by temperature variation and prestress-force change. Finally, finite element analyses are conducted to investigate the mechanism of temperature variation and prestress-loss effects on the impedance responses of prestressed tendon anchorage. Temperature effects on impedance monitoring are filtered by effective frequency shift-based algorithm for distinguishing prestress-loss effects on impedance signatures.
In this paper, a portable PZT interface for tension force monitoring in the cable-anchorage subsystem is developed. Firstly, the theoretical background of the impedance-based method is presented. A few damage evaluation approaches are outlined to quantify the variation of impedance signatures. Secondly, a portable PZT interface is designed to monitor impedance signatures from the cable-anchorage subsystem. One degree-of-freedom analytical model of the PZT interface is established to explain how to represent the loss of cable force from the change in the electromechanical impedance of the PZT interface as well as reducing the sensitive frequency band by implementing the interface device. Finally, the applicability of the proposed PZT-interface technique is experimentally evaluated for cable force-loss monitoring in a lab-scaled test structure.
Palladium nanoparticles (PdNPs) have intrinsic features, such as brilliant catalytic, electronic, physical, mechanical, and optical properties, as well as diversity in shape and size. The initial researches proved that PdNPs have impressive potential for the development of novel photothermal agents, photoacoustic agents, antimicrobial/antitumor agents, gene/drug carriers, prodrug activators, and biosensors. However, very few studies have taken the benefit of the unique characteristics of PdNPs for applications in the biomedical field in comparison with other metals like gold, silver, or iron. Thus, this review aims to highlight the potential applications in the biomedical field of PdNPs. From that, the review provides the perceptual vision for the future development of PdNPs in this field.
In this study, a preload monitoring method using impedance signatures obtained from a piezoelectric-based smart interface is presented for bolted girder connections. Firstly, the background theory of the piezoelectric-based smart interface and its implementation into the health monitoring of bolted connections are outlined. A simplified electro-mechanical (EM) impedance model of a smart interface-embedded bolted connection system is formulated to interpret a mechanistic understanding of the EM impedance signatures under the effect of bolt preload. Secondly, finite element modeling of a bolted connection is carried out to show the numerical feasibility of the presented method, and to predetermine the sensitive frequency band of the impedance signatures. Finally, impedance measurements are conducted on a lab-scaled bolted girder connection, to verify the predetermined sensitive frequency range and to assess the bolt preload changes in the test structure.
Summary
In this study, a temperature compensation method based on radial basis function network (RBFN) is developed to monitor damage‐induced impedance signatures in prestressed tendon anchorages under temperature variation. First, an impedance monitoring technique via a piezoelectric interface device is outlined for prestress‐loss detection in the tendon anchorage system. Second, an RBFN‐based algorithm is designed to filter out the temperature‐induced variation in impedance signatures for damage monitoring. Finally, the feasibility of the proposed algorithm is verified for the prestress‐loss monitoring in the test structure under the temperature‐varying condition. A series of impedance measurements are conducted for the temperature‐varying and prestress force‐varying conditions. The RBFN‐based algorithm is used to train a set of baseline impedance signatures for varying temperatures, and also to quantify damage‐induced impedance signatures of the test structure. The effect of the size of RBFN training patterns on the accuracy of the proposed temperature compensation algorithm is also evaluated.
Force changes in axially loaded members can be monitored by quantifying variations in impedance signatures. However, statistical damage metrics, which are not physically related to the axial load, often lead to difficulties in accurately estimating the amount of axial force changes. Inspired by the wearable technology, this study proposes a novel wearable piezoelectric interface that can be used to monitor and quantitatively estimate the force changes in axial members. Firstly, an impedance-based force estimation method was developed for axially loaded members. The estimation was based on the relationship between the axial force level and the peak frequencies of impedance signatures, which were obtained from the wearable piezoelectric interface. The estimation of the load transfer capability from the axial member to the wearable interface was found to be an important factor for the accurate prediction of axial force. Secondly, a prototype of the wearable piezoelectric interface was designed to be easily fitted into existing axial members. Finally, the feasibility of the proposed technique was established by assessing tension force changes in a numerical model of an axially loaded cylindrical member and a lab-scale model of a prestressed cable structure.
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