Distribution of Articles published per year
(2009 - 2019)
(2009 - 2019)
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Article 0 Reads 0 Citations Concrete Crack Detection and Monitoring Using a Capacitive Dense Sensor Array Published: 18 April 2019
Sensors, doi: 10.3390/s19081843
Cracks in concrete structures can be indicators of important damage and may significantly affect durability. Their timely identification can be used to ensure structural safety and guide on-time maintenance operations. Structural health monitoring solutions, such as strain gauges and fiber optics systems, have been proposed for the automatic monitoring of such cracks. However, these solutions become economically difficult to deploy when the surface under investigation is very large. This paper proposes to leverage a novel sensing skin for monitoring cracks in concrete structures. This sensing skin is constituted of a flexible electronic termed soft elastomeric capacitor, which detects a change in strain through changes in measured capacitance. The SEC is a low-cost, durable, and robust sensing technology that has previously been studied for the monitoring of fatigue cracks in steel components. In this study, the sensing skin is introduced and preliminary validation results on a small-scale reinforced concrete beam are presented. The technology is verified on a full-scale post-tensioned concrete beam. Results show that the sensing skin is capable of detecting, localizing, and quantifying cracks that formed in both the reinforced and post-tensioned concrete specimens.
Article 1 Read 0 Citations Use of flexible sensor to characterize biomechanics of canine skin Published: 25 January 2019
BMC Veterinary Research, doi: 10.1186/s12917-018-1755-y
Suture materials and techniques are frequently evaluated in ex vivo studies by comparing tensile strengths. However, the direct measurement techniques to obtain the tensile forces in canine skin are not available, and, therefore, the conditions suture lines undergo is unknown. A soft elastomeric capacitor is used to monitor deformation in the skin over time by sensing strain. This sensor was applied to a sample of canine skin to evaluate its capacity to sense strain in the sample while loaded in a dynamic material testing machine. The measured strain of the sensor was compared with the strain measured by the dynamic testing machine. The sample of skin was evaluated with and without the sensor adhered. In this study, the soft elastomeric capacitor was able to measure strain and a correlation was made to stress using a modified Kelvin-Voigt model for the canine skin sample. The sensor significantly increases the stiffness of canine skin when applied which required the derivation of mechanical models for interpretation of the results. Flexible sensors can be applied to canine skin to investigate the inherent biomechanical properties. These sensors need to be lightweight and highly elastic to avoid interference with the stress across a suture line. The sensor studied here serves as a prototype for future sensor development and has demonstrated that a lightweight highly elastic sensor is needed to decrease the effect on the sensor/skin construct. Further studies are required for biomechanical characterization of canine skin. The online version of this article (10.1186/s12917-018-1755-y) contains supplementary material, which is available to authorized users.
Article 0 Reads 0 Citations Thin-Film Sensor for Fatigue Crack Sensing and Monitoring in Steel Bridges under Varying Crack Propagation Rates and Ran... Published: 01 January 2019
Journal of Aerospace Engineering, doi: 10.1061/(asce)as.1943-5525.0000940
Article 0 Reads 0 Citations Variable input observer for nonstationary high-rate dynamic systems Published: 11 December 2018
Neural Computing and Applications, doi: 10.1007/s00521-018-3927-x
Article 0 Reads 0 Citations Development of wireless sensor node hardware for large-area capacitive strain monitoring Published: 20 November 2018
Smart Materials and Structures, doi: 10.1088/1361-665x/aaebc6
Conventional resistive-type strain sensing methods have limitations in large-area sensing due to their relatively small size. The soft elastomeric capacitive (SEC) sensor is a capacitance-based stretchable electronic strain sensor, which has shown distinct advantages for mesoscale sensing over conventional strain-based structural health monitoring (SHM) due to its wide surface coverage capability. While recent advances in wireless sensor technologies have provided an attractive alternative to wired and centralized SHM, the capacitive strain sensing methods have not benefitted from the wireless approaches due to the lack of appropriate hardware element. This study develops a wireless sensor board to use the SEC sensor in combination with a wireless sensor network for SHM by addressing key implementation challenges. An alternating current (AC)-based De-Sauty Wheatstone bridge circuit is employed, converting dynamic capacitance variation from the SEC sensor into analog voltage signal. A high-precision bridge balancer and two-step signal amplifiers are implemented to effectively apply for low-level structural strain vibrations. An amplitude modulation (AM)-demodulator has been designed to extract the baseband signal (i.e. strain signal) from the carrier signal (i.e. AC excitation for the Wheatstone bridge). And a dual-step shunt calibrator has been proposed to remove the parasitic capacitance effect of lead wires during on-board calibration process. The performances of the sensor board developed in this study have been validated via a series of lab tests, outperforming a conventional wired capacitance measurement system.
PROCEEDINGS-ARTICLE 0 Reads 0 Citations Advanced Materials and Designs for Hydraulic, Earth, and Aerospace Structures Published: 15 November 2018
Earth and Space 2018, doi: 10.1061/9780784481899.079