Strain Gauges, Fiber Optic versus Electric

Author(s):  
Shiping Chen ◽  
James S. Sirkis
Keyword(s):  
2013 ◽  
Vol 53 (6) ◽  
pp. 872-877
Author(s):  
Dita Jiroutová ◽  
Miroslav Vokáč

In recent years, the field of structure monitoring has been making increasing use of systems based on fiber-optic technologies. Fiber-optic technology offers many advantages, including higher quality measurements, greater reliability, easier installation and maintenance, insensitivity to the environment (mainly to the electromagnetic field), corrosion resistance, safety in explosive and flammable environments, the possibility of long-term monitoring and lower cost per lifetime. We have used SOFO fibre-optic strain gauges to perform measurements to check the overall relative deformation of a real reinforced concrete structure. Long-term monitoring of the structure revealed that the measurement readings obtained from these fibre-optic strain gauges differed from each other. Greater attention was therefore paid to the calibration of the fibre-optic strain gauges, and to determining their measurement accuracy. The experimental results show that it is necessary to calibrate SOFO strain gauges before they are used, and to determine their calibration constant.


2021 ◽  
Vol 20 (4) ◽  
pp. 005-016
Author(s):  
Damian Nykiel

This work includes a comparison of the methods of monitoring the deformations of a structure on the example of a flat plate slab test. Classic ESG (electrofusion strain gauges) and modern DFOS (distributed fiber optic sensors) were compared. During the research, both types of sensors were used on some of the reinforcing bars. The study aims to indicate the differences between the compared monitoring methods, both in terms of the obtained results and their utility values.


Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 188
Author(s):  
Manuel Bertulessi ◽  
Daniele Fabrizio Bignami ◽  
Ilaria Boschini ◽  
Marco Brunero ◽  
Maddalena Ferrario ◽  
...  

We present a case study of a Structural Health Monitoring (SHM) hybrid system based on Brillouin Distributed Fiber Optic Sensors (D-FOS), Vibrating Wire (VW) extensometers and temperature probes for an existing historical water penstock bridge positioned in a mountain valley in Valle d’Aosta Region, Northwestern Italy. We assessed Brillouin D-FOS performances for this kind of infrastructure, characterized by a complex structural layout and located in a harsh environment. A comparison with the more traditional strain monitoring technology offered by VW strain gauges was performed. The D-FOS strain cable has been bonded to the concrete members using a polyurethane-base adhesive, ensuring a rigid strain transfer. The raw data from all sensors are interpolated on a unique general timestamp with hourly resolution. Strain data from D-FOS and VW strain gauges are then corrected from temperature effects and compared. Considering the inherent differences between the two monitoring technologies, results show a good overall matching between strain time series collected by D-FOS and VW sensors. Brillouin D-FOS proves to be a good solution in terms of performance and economic investment for SHM systems on complex infrastructures such as hydropower plants, which involve extensive geometry combined with the need for detailed and continuous strain monitoring.


1994 ◽  
Vol 120 (8) ◽  
pp. 1696-1717 ◽  
Author(s):  
S. F. Masri ◽  
M. S. Agbabian ◽  
A. M. Abdel‐Ghaffar ◽  
M. Higazy ◽  
R. O. Claus ◽  
...  

1994 ◽  
Author(s):  
Norbert Fuerstenau ◽  
Walter Schmidt ◽  
Douglas D. Janzen ◽  
R. Schuetze ◽  
H. C. Goetting

1992 ◽  
Vol 31 (34) ◽  
pp. 7178 ◽  
Author(s):  
Tomas Valis ◽  
Dayle Hogg ◽  
Raymond M. Measures

1993 ◽  
Author(s):  
T. G. Beck Mason ◽  
Tomas Valis ◽  
W. D. Hogg
Keyword(s):  

Author(s):  
Stephen G. Raymer ◽  
Dara W. Childs

A new method for measuring forces in magnetic bearings is presented. Fiber-optic strain gauges (FOSGs) mounted to the side of the magnet poles are used to detect the small levels of strain that the metal experiences as the bearing exerts a force. These strains can be converted into force components, providing measurements with a previously unattainable level of accuracy and precision. Tests were done using the Magnetic Bearing Test Rig at the Texas A&M University Turbomachinery Laboratory. Two FOSGs were placed approximately 90° apart on two separate poles of one of the bearings, and the strain levels for different load magnitudes and directions were measured. The raw signal has several undesirable attributes that prevent an accurate static measurement. However, dynamic measurements proved to be very effective in the frequency domain, as most of the noise in the signal is confined to frequencies below 1 Hz. Due to the raw signal characteristics, new techniques for load application and calibration were developed. By using these new approaches, an equation relating reaction force components and strain was generated. This equation provides precise knowledge of any force vector in the bearing. An uncertainty analysis was performed on the resulting equation, providing a measure of resolution and a reduction in error several times more precise than any previous result. As a result of these findings, magnetic bearings can now be used to perform precise diagnostic analysis, determine rotordynamic coefficients, and improve magnetic bearing design and performance.


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