Fiber Bragg Grating Accelerometer Research Articles

Highly stabilized fiber Bragg grating accelerometer based on cross-type diaphragm

A fiber Bragg grating (FBG) accelerometer based on cross-type diaphragm was proposed and designed, in which the cross-beam acts as a spring element. To balance the sensitivity and stability, the accelerometer structure was optimized. The experimental results show that the designed device has a resonant frequency of 556 Hz with a considerable wide frequency bandwidth of up to 200 Hz, which is consistent with the simulation. The sensitivity of the device is 12.35 pm/g@100 Hz with a linear correlation coefficient of 0.99936. The proposed FBG accelerometer has simple structure and strong anti-interference capability with a maximal cross-error less than 3.26%, which can be used for mechanical structural health monitoring.

Dual straight-wing FBG accelerometer for low-frequency vibration measurement

Fiber optic accelerometers have a wide range of applications in low-frequency vibration measurement, such as in earthquake monitoring, disaster early warning, underground resource exploration, and anti-seismic monitoring projects for critical structures like dams and bridges. In response to the current issues of Fiber Bragg Gratings (FBG) accelerometers being insensitive to low-frequency vibration signals and challenging to apply in engineering, a dual straight-wing FBG accelerometer for low-frequency vibration measurement is proposed. Firstly, a sensor model is established and theoretically analyzed. Secondly, the impact of the sensor's main structural parameters on sensitivity and natural frequency is analyzed, and the sensor is simulated using ANSYS. Finally, a prototype of the sensor is developed, and a low-frequency vibration testing system is set up to test the sensor's performance. Experimental results show that the accelerometer has a natural frequency of 39.1 Hz, operates in the 5–22 Hz frequency band, and has a sensitivity of 171.7 p.m./g, a dynamic range of 69.82 dB, and a transverse interference resistance of less than 9.5%. This research provides a new reference for the development of similar sensors.

Development of a Fiber Bragg Grating accelerometer based on a tandem single-notched hinge structure

A Fiber Bragg Grating low-frequency accelerometer with a single-notched hinge in series is proposed to improve the hinge structure’s sensitivity and the cross-sensitivity of the accelerometer of low-frequency seismic waves. The sensitivity and the cross-sensitivity of the accelerometer are improved by connecting the single-notched hinge structure in series and experimentally verified. Based on the theoretical analysis, the resonance frequency and sensitivity formula of the accelerometer are derived. At the same time, the accelerometer is simulated by finite element analysis software to simulate and analyze the characteristics of the accelerometer in terms of resonance frequency, strain distribution, and amplitude-frequency response. The structural parameters of the accelerometer are optimized by numerical analysis software, and the effects of the structural parameters on the sensitivity and resonance frequency of the accelerometer are analyzed. The experimental results show that the resonance frequency of the accelerometer is 110 Hz, the flat region is 0.6–50 Hz, the linearity is as high as 98.9%, the sensitivity is 1040.41 pm/g, and the cross-sensitivity of the accelerometer in the flat interval is 4.94%. This indicates that the accelerometer shows good linearity and cross-sensitivity in the flat interval, which well meets the needs of seismic wave signal monitoring in low-frequency oil and gas exploration.

Distributed strain monitoring method for structural vibration based on multi-point acceleration measurement

Fiber Bragg Grating (FBG) has been widely used in vibration monitoring due to its advantages of high sensitivity, resistance to electromagnetic interference and ease of networking. This paper proposes a method of distributed strain monitoring for vibrating structures where the surface is unsuitable for attaching FBG. This method utilizes measured multi-point acceleration to calculate dynamic displacement, and subsequently reconstructs distributed strain based on displacement matching and a displacement–strain function. Finite element simulation results demonstrate that the displacement matching scheme has higher strain reconstruction accuracy and broader adaptability. An FBG accelerometer with an equal-strength beam is designed, fabricated, and tested, exhibiting a resonant frequency of 56 Hz and an average sensitivity of 70 pm·g−1 in the flat frequency band. The proposed method is experimentally validated using a 12 m steel pipeline. It’s demonstrated that the displacement reconstruction error is less than 8 %, and the strain reconstruction error is less than 11 %.

A medium-high frequency FBG accelerometer based on a V-shaped flexible hinge

Acquiring medium- and high-frequency acceleration signals is vital for broad infrastructure health monitoring, such as bridges, railways, and tunnels. This article introduces an innovative fiber Bragg grating (FBG) accelerometer featuring a V-shaped flexure hinge structure with enhanced sensitivity. Theoretical calculation and simulation analysis software were employed to evaluate the proposed structure's parameters. Experimental results show a sensitivity of approximately 67.9 pm/G under a working bandwidth of 400–900 Hz and a resonant frequency of 1250 Hz. The influence of temperature at 8.4 pm/°C and transverse interference validate 3.5%. These findings align with simulations, affirming the sensor's performance. This innovation holds promise for enhancing structural integrity monitoring in large-scale structures by detecting medium- and high-frequency vibration measurements.

A symmetrical dual-mass block fiber Bragg grating vibration sensor based on a V-shaped flexible hinge

Real-time monitoring of vibration properties in micro-seismic applications, such as petroleum exploration, physical oceanography, and perimeter security, is important for deep exploration and the prediction of geological disasters and other fields. The fiber Bragg grating (FBG) vibration sensor with symmetrical V-shaped flexible hinges and a dual mass block is proposed. Utilizing formula derivation and simulation software, the sensor's structural parameters are optimized and subjected to analysis. These simulations inform the fabrication of the actual sensor, and subsequently, the sensor's performance is empirically tested. The results show an average sensitivity of 73.86 pm/G and a natural frequency of 800 Hz, with a working range of 20–340 Hz. Its exhibits anti-interference in the transverse direction is less than 5 % during vibration measurement. The research outcomes offer a point of guidance for the progress of FBG accelerometer development within applications that involve measuring low- to medium-frequency accelerations.

Cascadable Four-Core Fiber Bragg Gratings Accelerometer for 2-D Low-Frequency Vibration Measurement

Cascadable Four-Core Fiber Bragg Gratings Accelerometer for 2-D Low-Frequency Vibration Measurement

Vector fiber Bragg gratings accelerometer based on silicone compliant cylinder for low frequency vibration monitoring

Vector accelerometer has attracted much attention for its great application potential in underground seismic signal measurement. We propose and demonstrate a novel vector accelerometer based on the three fiber Bragg gratings (FBGs) embedded in a silicone rubber compliant cylinder at 120° distributed uniformly. The accelerometer is capable of detecting the orientation of vibration with a range of 0°–360° and the acceleration through monitoring the central wavelength shifts of three FBGs simultaneously. The experimental results show that the natural frequency of the accelerometer is about 85 Hz, and the sensitivity is 84.21 pm/g in the flat range of 20 Hz–60 Hz. Through experimental calibration, the designed accelerometer can accurately obtain vibration vector information, including vibration orientation and acceleration. In addition, the range of resonant frequency and sensitivity can be expanded by adjusting the hardness of the silicone rubber materials. Due to the characteristics of small size and orientation recognition, the accelerometer can be applied to low-frequency vibration acceleration vector measurement in narrow spaces.

Low frequency fiber optic accelerometer based on lever amplification structure

Combined with the lever amplification principle, this paper designed a fiber Bragg grating (FBG) accelerometer based on the structure of an equal-section cantilever beam, which can weaken the contradiction between the lateral immunity and sensitivity of the equal-section cantilever beam. Increasing the thickness of the beam increases its stiffness, thus improving the lateral immunity of the beam; at the same time, the lever structure increases the axial strain of the FBG, further enhancing the sensitivity of the accelerometer. The experimental study and theoretical analysis of the accelerometer show that the accelerometer response sensitivity is 239.12 pm/G with a good fit of R2 = 0.995 for frequencies varying from 5 to 90 Hz and accelerations varying from 0.1 to 1G; the lateral anti-interference degree is less than 6.27%. It shows that the accelerometer has good sensing performance. And the structure is simple and easy to package. The thickness of the beam or the length of the lever can be changed to further extend the measurement range of the accelerometer.

Recent Advances in Multidimensional Fiber Bragg Grating Accelerometers

Fiber Bragg grating (FBG) accelerometers measure vibrations by demodulating wavelength shifts induced by dynamic strain. Their high-temperature resistance and multiplexing capabilities provide them with opportunities for quasi-distributed applications in harsh environments. The basic principle of an FBG accelerometer is based on vibration-strain coupling. In the design of a sensor's mechanical structure, improving the coupling efficiency can effectively enhance the sensitivity of the accelerometer. Moreover, an FBG accelerometer can be developed as a multidimensional sensor, which is a unique feature compared to distributed-fiber vibration-sensing technology. In this paper, we review the recent advances in FBG accelerometer developments and by focusing on two main trends: sensitivity enhancement and orientation identification. We emphatically introduce new techniques for FBG accelerometers including hybrid strain loading, thin-cladding fiber FBGs, multicore FBGs and cladding FBGs.

Shock accelerometer based on fiber Bragg grating sensor with a novel 3D printed structure for medium frequency measurement applications and high acceleration range

This study aims to develop a shock accelerometer that can measure signals from two directions in one-dimensional space for medium frequency measurement applications and high acceleration range. A fiber Bragg grating (FBG) sensor is attached to a structure fabricated using Fused Deposition Modeling technology (FDM) to achieve this. The finite element method is utilized to observe the sensor’s operating mechanism and harmonic response, as well as to demonstrate the accelerometer’s customizability. The sensor’s design enables it to detect acceleration resulting from shock motion on both sides (+X and –X direction) of the Hopkinson bar system. When the elastic structure deforms, the wavelength inside the FBGs’ core changes. During the test with different random accelerations, FBG1 showed a total Bragg wavelength shift of 6.403 nm within the 450 g to 1800 g range, while FBG2 showed a total shift of 2.033 nm within the 330 g to 1200 g range. According to the findings of the linearity analysis conducted on the proposed sensor, the linear values of the data obtained from FBG1 were over 96%, while those from FBG2 were close to 94%. In addition, the sensor’s harmonic response was examined, and it was recommended that the sensor be operated within a frequency range of 20 to 600 Hz, with the resonant frequency being 660 Hz. The sensor’s amplitude anti-interference is also considered negligible when the horizontal noise signal relative to the working axis signal is less than 3% in both directions. These findings suggest that the proposed accelerometer has great potential for various applications. Furthermore, the proposed FBG accelerometer sensor utilizes 3D printing technology, which offers several advantages, including rapid fabrication time, reduced production costs, and high customizability.

Design and test of a FBG acceleration sensor basedon multi-stage flexible hinges.

High-precision and high-sensitivity vibration acceleration sensors have been a research hotspot in engineering technology, which play an important role in engineering structural health monitoring, earthquakes, tsunamis, and geological exploration. A novel, to the best of our knowledge, fiber Bragg grating (FBG) acceleration sensor incorporating a mass block and flexible hinge was proposed against the low sensitivity and poor transverse interference resistance of existing FBG acceleration sensors. The FBG accelerometer with the multi-stage flexible hinge was modeled and theoretically analyzed, the structural parameters of the sensor were optimized and actual sensors were developed, and a sensor performance test experiment was carried out in the end. The result suggested that the sensor's natural frequency was as high as 1400Hz, and its response was flat in the frequency range of 50-800Hz; its sensitivity was 18.4pm/g, linearity R 2 was 0.9983, and transverse interference immunity was below 3.2%. The research findings offered a new way of thinking about high-precision and high-sensitivity vibration measurement in engineering technology.

Serially Connected Cantilever Beam-Based FBG Accelerometers: Design, Optimization and Testing.

We focus on the design, optimization, fabrication, and testing of fiber Bragg grating (FBG) cantilever beam-based accelerometers to measure vibrations from active seismic sources in the external environment. These FBG accelerometers possess several advantages, such as multiplexing, immunity to electromagnetic interference, and high sensitivity. Finite Element Method (FEM) simulations, calibration, fabrication, and packaging of the simple cantilever beam-based accelerometer based on polylactic acid (PLA) are presented. The influence of the cantilever beam parameters on the natural frequency and sensitivity are discussed through FEM simulation and laboratory calibration with vibration exciter. The test results show that the optimized system has a resonance frequency of 75 Hz within a measuring range of 5-55 Hz and high sensitivity of ±433.7 pm/g. Finally, a preliminary field test is conducted to compare the packaged FBG accelerometer and standard electro-mechanical 4.5-Hz vertical geophones. Active-source (seismic sledgehammer) shots are acquired along the tested line, and both systems' experimental results are analyzed and compared. The designed FBG accelerometers demonstrate suitability to record the seismic traces and to pick up the first arrival times. The system optimization and further implementation offer promising potential for seismic acquisitions.

A Miniaturized Low-Frequency FBG Accelerometer Based on Symmetrical Cantilever Beam

Real-time monitoring of vibration characteristics of large-scale engineering structures such as buildings, bridges, and dams is important for research in structural health monitoring and other fields. Aiming at the key problem that the characteristic index and miniaturization of the existing fiber Bragg grating (FBG) accelerometer with a cantilever beam cannot be considered simultaneously, a miniaturized low-frequency FBG accelerometer with a symmetrical cantilever beam is proposed. Using formula derivation and analysis system (ANSYS) simulation software, the structural parameters of the sensor are optimized and simulated for analysis. According to the simulation results, the real sensor is made. Finally, the sensor performance is tested. The results show that the natural frequency of the sensor is about 72 Hz, which can be used to monitor vibration signals in the frequency range of 8–52 Hz. The sensitivity of the sensor is about 681.7 pm/g, and the resistance to transverse interference is less than 4.9%. Its volume is only 6.48 cm3, which is much smaller than that of an FBG accelerometer of the same kind. The research results provide a reference for the development of an FBG accelerometer of the same type.

Fabrication and testing of FBG sensor-based one-dimensional shock accelerometer attached to novel 3D printed structure

This study presents an FBG-based one-dimensional shock accelerometer fabricated by Fused Deposition Modelling (FDM) technology. The bare fiber Bragg grating (FBG) sensor is fixed to the 3D-printed elastomer structure. The dimension of the sensor was simulated by the finite element method to explore the customizability of the acceleration sensor. The deformation in the elastic material structure leads to a change in the wavelength of the FBG sensor, and it is observed that the total Bragg wavelength shift over the acceleration range was recorded as 2.53 nm, corresponding to an acceleration sensitivity of 1.16 pm/g with a randomly generated acceleration between 655 g and 2635 g (1 g = 9.81 m/s2). A linear analysis showed that the linear values of the data obtained in the experiments reached above 96%. A comparison of the accelerometer signal obtained from the piezoelectric accelerometer data with the FBG accelerometer shows an excellent match in pulse amplitudes with pulse durations of only about 100 μs each time the acceleration occurs and the proposed sensor operating frequency is from 200 to 3000 Hz. The proposed FBG acceleration sensor is based on 3D printing technology, so it also inherits the outstanding advantages of this technology such as fast manufacturing time, saving production costs, and especially the ability to easily customize based on the size change of the structure, weight of mass block or the printed material.

Resonant-Frequency-Adjustable Fiber Bragg Grating Accelerometer Based on Extra Transverse Force Loading

We propose a resonant-frequency-adjustable fiber Bragg grating (FBG) accelerometer. The accelerometer employs a special hexagonal energy transfer structure and a microhelical cylinder as a carrier. When the geophone vibrates, transverse force and axial force are applied to FBG at the same time, which breaks the traditional accelerometer that the FBG is only subjected to a single direction force. The resonant frequency can be changed by preadjusting the position of the microhelical cylinder. We introduced the structural principle and experimental model of the accelerometer and determined the structural parameters through finite-element simulation. In addition, we carried out a series of experimental tests, and the results show that the resonant frequency of the accelerometer can be increased from 680 to 980 Hz, and the frequency bandwidth is widened by 300 Hz. When the resonant frequency reaches 800 Hz, the maximum sensitivity can achieve 46.1 pm/g.

A novel short fiber Bragg grating accelerometer based on a V-type dual mass block structure for low- and medium-frequency vibration measurements

A novel short fiber Bragg grating (FBG) accelerometer based on a dual mass block structure is presented in this paper. The sensor is established on a solid, symmetrical design comprising a V-type beam. The configuration in the FBG accelerometer causes the FBG fiber to distort twice as much when subjected to external vibration. The theoretical research and optimization of the FBG accelerometer's natural frequency and sensitivity are performed using MATLAB software, while static structural stress and modal simulation analysis are examined using ANSYS software. An experimental test is applied to evaluate the implementation of the sensors. The natural frequency of the sensor is 880 Hz, and its stability frequency response is flat in the 20–340 Hz low- to middle-frequency range. The linearity of the average sensitivity is approximately 66.95 pm/g, and the transverse anti-interference of the FBG fiber is around 6.53%. This work proposes a suitable method to observe low- and medium-frequency vibration signals in large-scale applications.

High-Sensitivity Three-Axis FBG Accelerometer Based on Elliptical Spring

We propose an elliptical spring-based three-axis fiber Bragg grating (FBG) accelerometer fabricated by appropriately arranging and encapsulating three identical one-axis sensing structures in a cylindrical shell. The derived theoretical equations and the established simulation model of the sensing structure are in good agreement with the experimental results. Sensors on three axes operate in a frequency band of 10–70 Hz; the sensitivities of the proposed accelerometer in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> directions are 1197.82, 1157.78, and 1223.04 pm/g, respectively, showing high sensitivity, good consistency, directional response, and resistance to transverse interference.

A 2-D Fiber Bragg Grating Acceleration Sensor Based on Circular Flexure Hinges Structure

This work proposes and experimentally validates a 2D low- and medium-frequency fiber Bragg grating (FBG) acceleration sensor. The investigation of the vibration sensor uses a symmetrical circular flexure hinge structure with similar sensitivity in both measuring directions. The two FBGs are arranged differently to avoid a temperature impact; the sensitivity is double that of only one FBG fiber. First, the operating theory and theoretical system of the FBG accelerometer were analyzed. Second, the theoretical research and optimization improved the FBG sensor’s design, resonance frequency, and sensitivity. Third, the viability of the optimization findings and the simulation was evaluated using ANSYS software. Finally, the product was created, and the sensor calibration was performed using the simulation results. The theoretical values and experimental findings largely concur. According to performance tests, the resonance frequencies in the x- and y-direction are 440 and 500 Hz, respectively, with a flat frequency range from 20 to 300 Hz. Furthermore, the sensor shows average sensitivities along the two spatial dimensions of 124 and 83 pm/G, respectively. The overall anti-interference between the two measuring directions is less than 6%. This sensor is useful in various applications, including vibration monitoring, machine condition monitoring, and robotics.

Fiber Bragg Grating Accelerometer Based on F-beam

Fiber Bragg Grating Accelerometer Based on F-beam