Yuegang Tan

A non-contact fiber Bragg grating vibration sensor

A non-contact vibration sensor based on fiber Bragg grating (FBG) sensing has been proposed and studied in this paper. The principle of the sensor as well as simulation and experimental analyses are introduced. When the distance between the movable head and the measured shaft changed, the diaphragm deformed under magnetic coupling of the permanent magnet on the measured magnetic shaft. As a result, the center wavelength of the FBG connected to the diaphragm changed, based on which the vibration displacement of the rotating shaft could be obtained. Experimental results show that the resonant frequency of the sensor is about 1500 Hz and the working band ranges within 0-1300 Hz, which is consistent with the simulation analysis result; the sensitivity is -1.694 pm/μm and the linearity is 2.92% within a range of 2-2.4 mm. It can be used to conduct non-contact measurement on the vibration of the rotating shaft system.

Fiber Bragg Grating Sensing-Based Online Torque Detection on Coupled Bending and Torsional Vibration of Rotating Shaft

This paper has presented a novel approach based on fiber Bragg grating (FBG) sensing to analyze and decouple the coupled bending and torsional vibration of a rotating shaft. The theoretical FBG-based strain detection models under pure torsional vibration and coupled bending and torsional vibration have been derived. Two FBG sensors have been attached on the opposite sides of a rotating shaft with an angle of 45° with respect to the axial direction to support the use of the proposed decoupling method and determine the decoupled bending and torsion signals. A new supporting device has been designed to protect the fiber optical rotary joint from damage under large load impact, and ensure the stable signal transmit. The calibrated sensitivity of the pasted FBGs for measuring torque is 7.02 pm/

A Diaphragm Type Fiber Bragg Grating Vibration Sensor Based on Transverse Property of Optical Fiber With Temperature Compensation

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A temperature-independent force transducer using one optical fiber with multiple Bragg gratings

. Dynamic experiments on a rotor platform under different rotating speeds have been performed to effectively decouple the bending strain and torsional strain in real time. The decoupled torque measurements have shown a close agreement with the data detected from a commercial tacho-torquemeter, which demonstrated the effectiveness of the proposed decoupling method.

A High-Sensitivity Fiber Bragg Grating Displacement Sensor Based on Transverse Property of a Tensioned Optical Fiber Configuration and Its Dynamic Performance Improvement

This paper has presented a novel diaphragm-type fiber Bragg grating (FBG) vibration sensor with a small mass and an excellent sensitivity through the use of the transverse property of a tightly suspended optical fiber with two fixed ends. Two suspended optical fibers that were embedded with an FBG element each, have been arranged symmetrically along the both sides of the diaphragm in a parallel manner, and their middle points were connected with the two surfaces of the mass by rigid thin rods to sense vibration. The theoretical model of the presented sensor has been derived, and its sensing characteristics have been analyzed by numerical simulation to determine the physical parameters. Experiments have been conducted to show that its sensitivity is 31.25 pm/g within a working bandwidth range of 10~150 Hz. The linearity and relative sensitivity errors are 2.21% and ±10%, respectively. The experimental resonant frequency of 300 Hz is consistent with the theoretical value, which has verified the effectiveness of the proposed theoretical model. The temperature response of this sensor has decreased to 1.32 pm/°C in the range of 30~90°C after implementing the temperature compensation. Compared with the existing diaphragm-enabled FBG vibration sensors, the proposed sensor enables to support the easy implementation of distributed measurement, and the small mass allows for detection on mass-sensitive structures.

Paralleled Structure-Based String-Type Fiber Bragg Grating Acceleration Sensor

Typical electrical or piezoelectric force sensors may fail in the industrial applications with strong electromagnetic interference (EMI). To address this issue, this paper develops a new temperature-independent force transducer based on theories of elastic cantilever beam and Bragg wavelength shift in fiber Bragg gratings. The detailed design of the structure and theoretical analysis are given to introduce the measurement principle of the transducer and temperature compensation of fiber Bragg gratings (FBG). Extensive experiments have been conducted to evaluate the performance of the developed force transducer. Experimental results demonstrate that the developed FBG force transducer has a force sensitivity 84.43 pm/kN within a measured range from 0 to 50 kN, which is consistent with the theoretical sensitivity 87.77 pm/kN. Moreover, experimentally the transducer also achieves good linearity, repeatability and temperature independency. The developed force transducer can assist in monitoring the states of heavy-duty machines in the harsh industrial environment.

A novel fault diagnostic technique for gearboxes under speed fluctuations without angular speed measurement

This paper presents a high-sensitivity fiber Bragg grating (FBG) displacement sensor with a novel configuration for structural health monitoring. The transverse movement of an optical fiber that has been configured as a tight suspension status with its two ends fixed has been utilized to measure displacement. The theoretical models for both static and dynamic displacements have been derived. The corresponding simulations have been conducted to determine the relationship between the model parameters and the sensor performance. This approach supports the sensor design improvement and structural optimization. Two small working ranges have been selected to determine the simplified linear model according to Taylor series. The sensitivity of this sensor can reach up to 490.1 pm/mm with a high resolution of

A Diaphragm-Type Highly Sensitive Fiber Bragg Grating Force Transducer With Temperature Compensation

2.04~\mu \text{m}

Study on non-contact Fiber Bragg grating vibration sensor

in a range of 1.4~2.0 mm. The introduction of the supporting spring unit has significantly enhanced the sensor’s resonant frequency without sacrificing the sensitivity. The application of the stiffer spring unit has enlarged the working bandwidth from 0~8 Hz to exceed 50 Hz. Enhancing the damping ratio unit can effectively improve the flatness of the dynamic response within the working bandwidth, while it does not affect other dynamic properties of the sensor. These improvements and design guidelines have been validated by both dynamic experiments and theoretical modeling.

Experimental study of dynamic strain for gear tooth using fiber Bragg gratings and piezoelectric strain sensors

This paper has presented a novel string-type fiber Bragg grating (FBG) acceleration sensor based on directly utilizing the transversal vibrational property of a tightly suspended optical fiber. This sensor mainly consists of a mass fixed on the middle of an optical fiber embedded with an FBG element and another optical fiber or metal beam in a parallel arrangement mode, which enables to enhance the impact resistance and resonant frequency of the sensor. Compared with existing FBG-based vibration sensors, the proposed sensor possesses an excellent repeatability using a simple structure, and avoids the FBG-pasting process and the associated limitations of chirping failure. The working principle of the proposed FBG vibration sensors with two different configurations has been built with considering the rotational interference of the mass. Static experiments have been completed to show that the sensitivity of the two configurations with paralleled optical fiber and metal beam is 193.6 and 3.275 pm/g, respectively. The paralleled metal beam-based vibration sensor has a working bandwidth of 12~250 Hz, much larger than that of 4~28 Hz for the paralleled string-type optical fiber configuration. The performance of the proposed acceleration sensor can be easily adjusted by arranging different types of the parallel structure and modifying their corresponding physical parameters to satisfy different vibration measurement requirements.