Performance Characteristics of Fiber-Optic Strain Sensors as Compared With Electrical Resistance and Vibrating Wire Strain Gauges

2017 ◽  
Vol 45 (6) ◽  
pp. 20160281
Author(s):  
K. Kim ◽  
M. Tia ◽  
J. Greene
Keyword(s):  
Electrical Resistance ◽  
Fiber Optic ◽  
Strain Sensors ◽  
Performance Characteristics ◽  
Strain Gauges ◽  
Vibrating Wire ◽  
Wire Strain ◽  
Fiber Optic Strain Sensors

scholarly journals Input Torque Measurements for Wind Turbine Gearboxes Using Fiber Optical Strain Sensors

2021 ◽  
Author(s):  
Unai Gutierrez Santiago ◽  
Alfredo Fernández Sisón ◽  
Henk Polinder ◽  
Jan-Willem van Wingerden
Keyword(s):  
Signal Processing ◽  
Wind Turbine ◽  
Fiber Optic ◽  
Strain Sensors ◽  
Strain Gauges ◽  
Ring Gear ◽  
Gear Mesh ◽  
Strain Data ◽  
Fiber Optic Strain Sensors ◽  
Input Torque

Abstract. Accurate knowledge of the input torque in wind turbine gearboxes is key to improving their reliability. Traditionally, rotor torque is measured using strain gauges bonded to the shaft. Transferring the resulting signal from the rotating shaft to a stationary data acquisition system while powering the sensing devices is complex and costly. The magnitude of the torques involved in wind turbine gearboxes and the high stiffness of the input shaft pose additional difficulties. This paper presents a new alternative method to measure the input torque in wind turbine gearboxes based on deformation measurements of the static first stage ring gear. We have measured deformation using fiber optic strain sensors based on fiber Bragg gratings because of their advantages compared to conventional electrical strain gauges. The present study was conducted on a Siemens Gamesa Renewable Energy gearbox with a rated power of 6MW, in which a total of 54 fiber optic strain sensors were installed on the outer surface of the first stage ring gear. The gear mesh forces between the planets and the ring gear cause measurable deformations on the outer surface of the stationary ring gear. The measured strains exhibit a dynamic behavior. The strain values change depending on the relative position of the strain sensors to the planet gears, the instantaneous variations of the input torque, and the way load is shared between planets. A satisfactory correlation has been found between the strain signals measured on the static ring gear and torque. Two signal processing strategies are presented in this paper. The first procedure is based on the peak-to-peak strain values computed for the gear mesh events, and therefore, torque can only be estimated when a gear mesh event is detected. The second signal processing procedure combines the strain signals from different sensors using a Coleman coordinate transformation and tracks the magnitude of the fifth harmonic component. With this second procedure, it is possible to estimate torque whenever strain data of all sensors is available, leading to an improved frequency resolution up to the sampling frequency used to acquire strain data. The method presented in this paper could make measuring gearbox torque more cost-effective, which would facilitate its adoption in serial wind turbines and enable novel data-driven control strategies, as well as a more accurate assessment of the consumed fatigue life of the gearboxes throughout their operation.

Evaluation of Negative Skin Friction on Bridge Abutment Piles

2021 ◽  
Vol 15 (2) ◽  
Author(s):  
Osama Drbe
Keyword(s):  
Skin Friction ◽  
Pore Water Pressure ◽  
Design Method ◽  
Water Pressure ◽  
Strain Gauges ◽  
Total Stress ◽  
Vibrating Wire ◽  
Negative Skin Friction ◽  
Drag Forces ◽  
Wire Strain

Piles are used to transfer loads of structures to deeper and stronger soil layers through skin friction and/or end bearing. Surcharge loads, site grading, or dewatering may induce downward movement of soil adjacent to piles installed in a compressible medium. This movement creates negative skin friction stresses acting downward at the pile-soil interface, which applies additional loads “drag forces” to the pile causing a maximum axial load in the pile shaft at the “neutral plane”. To evaluate the development of drag forces, a comprehensive field monitoring program was conducted over four years for three instrumented abutment H-piles as part of a three-span bridge project. The soil settlement and changes in pore water pressure in the soil adjacent to the piles due to the construction of an approach embankment were monitored using multiple-point extensometers and vibrating wire piezometers. The piles’ elastic settlement and strains were measured using single-point extensometers and vibrating wire strain gauges. The field measurements are presented and discussed in terms of responses time histories and load distribution along one pile shaft. In addition, the calculated forces from vibrating wire strain gauges are compared with the unified design method prediction considering the total stress method (α-method) for cohesive soils. The results show that the maximum drag force was developed after the complete dissipation of excess pore water pressure and that the location of neutral plane varied during the embankment construction stages. Employing the total stress method in the unified design method provided a reasonable prediction of the drag force and the neutral plane’s location.

scholarly journals Temperature and Strain Correlation of Bridge Parallel Structure Based on Vibrating Wire Strain Sensor

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 658 ◽  
Author(s):  
Lu Peng ◽  
Genqiang Jing ◽  
Zhu Luo ◽  
Xin Yuan ◽  
Yixu Wang ◽  
...  
Keyword(s):  
Sensor Data ◽  
Parallel Structure ◽  
Strain Gauges ◽  
Final Conclusion ◽  
Vibrating Wire ◽  
Traceability System ◽  
Wire Strain ◽  
Time Work ◽  
Long Time ◽  
Dynamic Acquisition

Deformation is a ubiquitous phenomenon in nature. This process usually refers to the change in shape, size, and position of an object in the time and spatial domain under various loads. Under normal circumstances, during engineering construction, technicians are generally required to monitor the safe operation of structural facilities in the transportation field and the health of bridge, because monitoring in the engineering process plays an important role in construction safety. Considering the reliability risk of sensors after a long-time work period, such as signal drift, accurate measurement of strain gauges is inseparable from the value traceability system of high-precision strain gauges. In this study, two vibrating wire strain gauges with the same working principle were measured using the parallel method at similar positions. First, based on the principle of time series, the experiment used high-frequency dynamic acquisition to measure the thermometer strain of two vibrating wire strain gauges. Second, this experiment analyzed the correlation between strain and temperature measured separately. Under the condition of different prestress, this experiment studied the influencing relationship of temperature corresponding variable. In this experiment, the measurement repetitiveness was analyzed using the meteorology knowledge of single sensor data, focused on researching the influence of temperature and prestress effect on sensors by analyzing differences of their measurement results in a specified situation. Then, the reliability and stability of dynamic vibrating wire strain gauge were verified in the experiment. The final conclusion of the experiment is the actual engineering in the later stage. Onsite online meteorology in the application provides support.

scholarly journals Numerical Analysis of the Effect of Microscale Components Interaction on Measurements of Fiber Optic Strain Sensors Used in Composite Structures

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Mikhail Tashkinov ◽  
Igor Shardakov
Keyword(s):  
Composite Material ◽  
Numerical Analysis ◽  
Optical Fiber ◽  
Composite Structures ◽  
Fiber Optic ◽  
Strain Tensor ◽  
Strain Sensors ◽  
Numerical Estimation ◽  
Structural Components ◽  
Fiber Optic Strain Sensors

The paper investigates the influence of structural components of a composite material on the strain values measured by using an embedded optical fiber with Bragg gratings. The effect of composite plies and intermediate epoxy layers on the transfer of deformations from the measured object to the optical fiber was studied taking into account various methods of the fiber attachment and surrounding media configurations. A numerical estimation of the effect of the longitudinal and transverse components of the strain tensor on the wavelength of the reflected spectrum is performed.

In-line fiber etalon (ILFE) fiber-optic strain sensors

1995 ◽  
Vol 13 (7) ◽  
pp. 1256-1263 ◽  
Author(s):  
J. Sirkis ◽  
T.A. Berkoff ◽  
R.T. Jones ◽  
H. Singh ◽  
A.D. Kersey ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Strain Sensors ◽  
Fiber Optic Strain Sensors
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