Browsing by Subject "Strain measurement"

Now showing 1 - 4 of 4

Open Access
Distributed strain sensing by frequency-selective fading in phase-OTDR
(IEEE, 2024-10-29) Yıldız, Muhammed Kaan; Uyar, Faruk; Kartaloğlu, Tolga; Özbay, Ekmel; Özdür, İbrahim
We demonstrate a novel approach using frequency-selective fading in phase-OTDR systems to measure dynamic strain on a fiber optic cable. We present the measurements of 200 Hz, 0.03 με strain at 2 kHz interrogation frequency. CLEO 2024 © Optica Publishing Group 2024 © 2024 The Author(s)
Open Access
Lattice dynamics and elastic properties of lanthanum monopnictides
(2008) Gökoǧlu G.; Erkişi, A.
In this study, first principles calculation results of the second order elastic constants and lattice dynamics of two lanthanum monopnictides, LaN and LaBi, which crystallize in rock-salt structure (B1 phase), are presented. Calculations were based on plane wave basis sets and pseudopotential methods in the framework of Density Functional Theory (DFT) with generalized gradient approximation. Elastic constants are calculated by tetragonal and orthorhombic distortions on cubic structure. Phonon dispersion spectra was constructed in the linear response approach of the Density Functional Perturbation Theory (DFPT). The complete phonon softening with negative frequencies and large elastic anisotropy were observed for LaN single crystal as a sign of the structural instability. The phonon dispersion curve for LaBi is typical for lanthanum monopnictides and does not show any anomalous physical property. The calculated structural quantities for both LaN and LaBi systems agree well with the available experimental and theoretical data. © 2008 Elsevier Ltd. All rights reserved.
Open Access
Novel integrated optical displacement sensor for scanning force microscopies
(IEEE, 2003) Aydınlı, Atilla; Kıyat, İsa; Kocabaş, Coşkun
A novel displacement sensor for scanning force microscoples using an integrated optical micro-ring resonator is described. Device operates by monitoring the changes in transmission spectrum of micro-ring resonator. This design provides sensitivities about ∼10-4 Å-1.
Open Access
A wireless passive sensing system for displacement/strain measurement in reinforced concrete members
(MDPI AG, 2016) Ozbey B.; Erturk V.B.; Demir H.V.; Altintas, A.; Kurc O.
In this study, we show a wireless passive sensing system embedded in a reinforced concrete member successfully being employed for the measurement of relative displacement and strain in a simply supported beam experiment. The system utilizes electromagnetic coupling between the transceiver antenna located outside the beam, and the sensing probes placed on the reinforcing bar (rebar) surface inside the beam. The probes were designed in the form of a nested split-ring resonator, a metamaterial-based structure chosen for its compact size and high sensitivity/resolution, which is at µm/microstrains level. Experiments were performed in both the elastic and plastic deformation cases of steel rebars, and the sensing system was demonstrated to acquire telemetric data in both cases. The wireless measurement results from multiple probes are compared with the data obtained from the strain gages, and an excellent agreement is observed. A discrete time measurement where the system records data at different force levels is also shown. Practical issues regarding the placement of the sensors and accurate recording of data are discussed. The proposed sensing technology is demonstrated to be a good candidate for wireless structural health monitoring (SHM) of reinforced concrete members by its high sensitivity and wide dynamic range. © 2016 by the authors; licensee MDPI, Basel, Switzerland.