Laboratory Measurement of Excavation Disturbance Effect Due to Trenchless Construction Using Distributed Fiber Optics Strain Sensing

2019 ◽  
Vol 49 (3) ◽  
pp. 20180645
Author(s):  
Yue Li ◽  
Hao Wang ◽  
Jing Cai ◽  
Ge Song
Keyword(s):  
Fiber Optics ◽  
Laboratory Measurement ◽  
Strain Sensing ◽  
Trenchless Construction

scholarly journals Microanchored borehole fiber optics allows strain profiling of the shallow subsurface

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cheng-Cheng Zhang ◽  
Bin Shi ◽  
Song Zhang ◽  
Kai Gu ◽  
Su-Ping Liu ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Field Experiments ◽  
Fiber Optic ◽  
Strain Sensing ◽  
Near Surface ◽  
Shallow Subsurface ◽  
Buried Cables ◽  
Capacity Theory ◽  
Confining Pressures ◽  
Strain Determination

AbstractVertical deformation profiles of subterranean geological formations are conventionally measured by borehole extensometry. Distributed strain sensing (DSS) paired with fiber-optic cables installed in the ground opens up possibilities for acquiring high-resolution static and quasistatic strain profiles of deforming strata, but it is currently limited by reduced data quality due to complicated patterns of interaction between the buried cables and their surroundings, especially in upper soil layers under low confining pressures. Extending recent DSS studies, we present an improved approach using microanchored fiber-optic cables—designed to optimize ground-to-cable coupling at the near surface—for strain determination along entire lengths of vertical boreholes. We proposed a novel criterion for soil–cable coupling evaluation based on the geotechnical bearing capacity theory. We applied this enhanced methodology to monitor groundwater-related vertical motions in both laboratory and field experiments. Corroborating extensometer recordings, acquired simultaneously, validated fiber optically determined displacements, suggesting microanchored DSS as an improved means for detecting and monitoring shallow subsurface strain profiles.

A Strain Sensing Structural Health Monitoring System for Delaminated Composite Structures

2012 ◽  
Vol 249-250 ◽  
pp. 849-855 ◽  
Author(s):  
Andrea Alaimo ◽  
Alberto Milazzo ◽  
Calogero Orlando
Keyword(s):  
Structural Health Monitoring ◽  
Fiber Optics ◽  
Health Monitoring ◽  
Composite Structures ◽  
Piezoelectric Sensors ◽  
Strain Sensing ◽  
Health Monitoring System ◽  
Structural Health ◽  
Monitoring Model ◽  
Element Approach

Structural Health Monitoring (SHM) for composite materials is becoming a primary task due to their extended use in safety critical applications. Different methods, based on the use of piezoelectric transducers as well as of fiber optics, has been successfully proposed to detect and monitor damage in composite structural components with particular attention focused on delamination cracks.In the present paper a Structural Health Monitoring model, based on the use of piezoelectric sensors, already proposed by the authors for isotropic damaged components, is extended to delaminated composite structures. The dynamic behavior of the host damaged structure and the bonded piezoelectric sensors is modeled by means of a boundary element approach based on the Dual Reciprocity BEM. The sensitivity of the piezoelectric sensors has been studied by varying the delamination length characterizing the skin/stiffener debonding phenomenon of composite structures undergoing dynamic loads.

A Soft Optical Waveguide Coupled With Fiber Optics for Dynamic Pressure and Strain Sensing

2018 ◽  
Vol 3 (4) ◽  
pp. 3821-3827 ◽  
Author(s):  
Celeste To ◽  
Tess Hellebrekers ◽  
Jaewoong Jung ◽  
Sohee John Yoon ◽  
Yong-Lae Park
Keyword(s):  
Fiber Optics ◽  
Optical Waveguide ◽  
Dynamic Pressure ◽  
Strain Sensing

Spatial Strain Sensing Using Embedded Fiber Optics

JOM ◽  
2019 ◽  
Vol 71 (4) ◽  
pp. 1528-1534 ◽  
Author(s):  
Adam Hehr ◽  
Mark Norfolk ◽  
John Sheridan ◽  
Matthew Davis ◽  
William Leser ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Strain Sensing

Analyzing the Strain Sensing Response of Photoactive Thin Films Using Absorption Spectroscopy

2013 ◽  
Vol 569-570 ◽  
pp. 695-701 ◽  
Author(s):  
Dong Hyeon Ryu ◽  
Kenneth J. Loh
Keyword(s):  
Thin Films ◽  
Fiber Optics ◽  
Absorption Spectroscopy ◽  
Light Absorption ◽  
Time History ◽  
Form Factors ◽  
High Energy ◽  
Strain Sensing ◽  
Photoactive Layer ◽  
Photocurrent Generation

Structural health monitoring systems are required for detecting damage in structures so as to facilitate their timely maintenance and repair and to prevent catastrophic structural failure. To date, a variety of different sensor platforms (e.g., piezoelectric materials, fiber optics, and wireless sensors) have been proposed for SHM. However, they still suffer from high energy demand, large form factors, and durability issues, particularly when applied for monitoring space structures and reusable spacecraft. In a previous study, a bio-inspired and photocurrent-based strain sensor has been developed. This poly(3-hexylthiophene) (P3HT)-based nanocomposite sensor has been shown to generate photocurrent whose magnitude varies in tandem with applied strain. However, the photocurrent generation performance of the sensor is quite low. In addition, the strain sensing mechanism is not fully understood. In this study, the performance of the photoactive thin films were enhanced, and its strain sensing characteristics were analyzed using ultraviolet-visible (UV-Vis) absorption spectroscopy. First, multilayered photoactive and P3HT-based thin films were assembled via spin coating. The photocurrent generation performance of the films was evaluated using two methodologies, namely its photocurrent time history and current-voltage (IV) response. Uniform coating of the photoactive layer and high purity aluminum electrodes were crucial for improving their photocurrent generation. Second, light absorption properties of the P3HT-based photoactive layer were investigated at different strain levels using a UV-Vis spectrophotometer. Light absorption was shown to vary linearly with applied tensile strains.

Designing high-resolution slow scan CCD-based TEM camera systems

1992 ◽  
Vol 50 (2) ◽  
pp. 946-947
Author(s):  
James F. Mancuso ◽  
William B. Maxwell ◽  
Russell E. Camp ◽  
Mark H. Ellisman
Keyword(s):  
Fiber Optics ◽  
Ccd Camera ◽  
High Energy ◽  
Phosphor Layer ◽  
X Ray ◽  
Light Production ◽  
Camera Systems ◽  
X Ray Imaging ◽  
Electron Image ◽  
Scintillating Fiber

The imaging requirements for 1000 line CCD camera systems include resolution, sensitivity, and field of view. In electronic camera systems these characteristics are determined primarily by the performance of the electro-optic interface. This component converts the electron image into a light image which is ultimately received by a camera sensor.Light production in the interface occurs when high energy electrons strike a phosphor or scintillator. Resolution is limited by electron scattering and absorption. For a constant resolution, more energy deposition occurs in denser phosphors (Figure 1). In this respect, high density x-ray phosphors such as Gd2O2S are better than ZnS based cathode ray tube phosphors. Scintillating fiber optics can be used instead of a discrete phosphor layer. The resolution of scintillating fiber optics that are used in x-ray imaging exceed 20 1p/mm and can be made very large. An example of a digital TEM image using a scintillating fiber optic plate is shown in Figure 2.

Embedded training in the FOG-M (fiber optics guided missile)

1984 ◽  
Author(s):  
Dorothy L. Finley ◽  
Irving N. Alderman ◽  
M. Sue Bogner ◽  
Nancy B. Mitchell
Keyword(s):  
Fiber Optics
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