scholarly journals Verification of the Propagation Range of Respiratory Strain Using Signal Waveform Measured by FBG Sensors

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7076
Author(s):  
Shouhei Koyama ◽  
Atsushi Fujimoto ◽  
Yuma Yasuda ◽  
Yuuki Satou
Keyword(s):  
Fiber Type ◽  
Strain Sensor ◽  
Signal Amplitude ◽  
Living Body ◽  
Fbg Sensor ◽  
Measured Strain ◽  
Signal Period ◽  
Fbg Sensors ◽  
Bragg Grating Sensor ◽  
Strain Signal

The FBG (Fiber Bragg grating) sensor is an optical fiber type strain sensor. When a person breathes, strain occurs in the lungs and diaphragm. This was verified using an FBG sensor to which part of the living body this respiratory strain propagates. When measured in the abdomen, the signal waveforms were significantly different between breathing and apnea. The respiratory cycle measured by the temperature sensor attached to the mask and the strain cycle measured by the FBG sensor almost matched. Respiratory strain was measured in the abdomen, chest, and shoulder, and the signal amplitude decreased with distance from the abdomen. In addition, the respiratory rate could be calculated from the measured strain signal. On the other hand, respiratory strain did not propagate to the elbows and wrists, which were off the trunk, and the respiratory time, based on the signal period, could not be calculated at these parts. Therefore, it was shown that respiratory strain propagated in the trunk from the abdomen to the shoulder, but not in the peripheral parts of the elbow and wrist.

scholarly journals Measurement of Mechanical and Thermal Strains by Optical FBG Sensors Embedded in CFRP Rod

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Keunhee Cho ◽  
Sung Tae Kim ◽  
Young-Hwan Park ◽  
Jeong-Rae Cho
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Strain Sensor ◽  
Thermal And Mechanical Properties ◽  
Fbg Sensor ◽  
Thermal Test ◽  
Fbg Sensors ◽  
Thermooptic Coefficient

The present study intends to provide the photoelastic coefficient and thermal expansion coefficient needed to use an FBG-embedded CFRP rod (smart rod) as strain sensor. Due to the monolithic combination of the FBG sensor with a CFRP rod, the smart rod is likely to exhibit thermal and mechanical properties differing from those of the bare FBG sensor. A tensile test showed that the photoelastic coefficient of the smart rod is 0.204, which is about 7.3% lower than the 0.22 value of the bare optical FBG. Moreover, the thermal expansion coefficient of the smart rod obtained through a thermal test appeared to be negative with a low value of −0.190×10−6/°C. Consequently, the temperature dependence of the smart rod is mainly expressed by means of the thermooptic coefficient. Compared to the bare FBG sensor, the smart rod is easier to handle and can measure compressive strains, which make it a convenient sensor for various concrete structures.

scholarly journals ANALYTICAL MODELS FOR ESTIMATION OF THE MAXIMUM STRAIN OF BEAM STRUCTURES BASED ON OPTICAL FIBER BRAGG GRATING SENSORS

2015 ◽  
Vol 22 (1) ◽  
pp. 86-91 ◽  
Author(s):  
Se Woon CHOI ◽  
Jihoon LEE ◽  
Byung Kwan OH ◽  
Hyo Seon PARK
Keyword(s):  
Maximum Stress ◽  
Strain Sensor ◽  
Elastic Beam ◽  
Analytical Models ◽  
Structural Safety ◽  
Maximum Strain ◽  
Beam Structures ◽  
Linear Elastic ◽  
Measured Strain ◽  
Fbg Sensors

The structural safety of a beam structure is assessed by a comparison between the maximum stress measured during monitoring and the allowable stress of the beam. However, the strain directly measured from a fiber Bragg grat- ing (FBG) strain sensor may not be identical with the actual maximum strain induced in the structural member. Unless a FBG strain sensor is installed exactly on where maximum strain occurs, the reliability of the evaluated safety based on the measured strain depends on the number and location of sensors. Therefore, in this paper, analytical models are presented for estimation of the maximum values of strains in a linear elastic beam using the local strains measured from FBG sensors. The model is tested in an experiment by comparing estimated maximum strain from FBG sensors and directly measured strain from electrical gages. For the assessment of safety of typical beam structures in buildings and infrastructures, analytical models for various loading and boundary conditions are provided.

Experiment Study on Shrink Strain Monitoring of Concrete in the Cure Period With FBG Sensors

2005 ◽  
Author(s):  
Li Sun ◽  
Hong-Nan Li ◽  
Liang Ren
Keyword(s):  
Temperature Sensor ◽  
Strain Measurement ◽  
Strain Sensor ◽  
Early Age ◽  
Thermal Drift ◽  
Experiment Study ◽  
Fbg Sensor ◽  
Strain Monitoring ◽  
Fbg Sensors ◽  
Ideal Method

Concrete is the material widely used in civil engineering. Cracks of concrete are mainly caused by the ununiform shrink in the cure period. The basic principle and merits of FBG are introduced. In order to monitor the shrink strain and temperature of concrete during the cure period, this paper presents a novelty strain sensor and temperature sensor based on FBG technology. The theoretical and experimental analyses of FBG sensor were implemented. The thermal drift experiment of sensor has also been carried out. Shrink strain and temperature of concrete have been successfully tested. The experiment results indicated that this monitor method is an ideal method in monitoring the concrete at the very early age. However, the thermal drift of FBG strain sensor should be considered during the strain measurement. This method could be used in monitoring the shrink strain and temperature of any volume concrete.

Study on Strain Transfer of Substrate Encapsulation FBG Strain Sensor

2014 ◽  
Vol 578-579 ◽  
pp. 1037-1041 ◽  
Author(s):  
Li Sun ◽  
Bo Zhang ◽  
Chuang Li ◽  
Chuan Yun Yue
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Multilayer Structure ◽  
Transfer Rate ◽  
Strain Sensor ◽  
Stress And Strain ◽  
Element Analysis ◽  
Strain Transfer ◽  
Fbg Sensor ◽  
Fbg Sensors

The FBG sensors of measuring stress and strain on the surface of concrete are mainly based on substrate encapsulation in engineering. Since the substrate encapsulation FBG sensor has a multilayer structure, there is certain consumption when the stress is transferred from the surface of concrete to optical fiber, which leads to difference between measured value and actual value. This paper analyzes the influencing factors of strain transfer rate by the method of theoretical calculation and finite element analysis. The formula of strain transfer is thereby obtained.

scholarly journals Installation Technique of Fiber Optic Sensor into FRP Used as NSM Structural Strengthening System

2020 ◽  
Vol 12 (20) ◽  
pp. 8501
Author(s):  
Soo-Yeon Seo ◽  
Jeong-Hun Park ◽  
Hyun-Do Yun ◽  
Kang-Su Kim
Keyword(s):  
Optical Fiber ◽  
Fiber Optic ◽  
Fiber Optic Sensor ◽  
Near Surface ◽  
Fbg Sensor ◽  
Optic Sensor ◽  
Near Surface Mounted ◽  
Fbg Sensors ◽  
Bragg Grating Sensor ◽  
Frp Strips

Recently, it has become necessary to develop a monitoring technology that combines an FBG (fiber Bragg grating) sensor as a means for continuously monitoring whether the reinforcing effect of an FRP (fiber-reinforced polymer) is maintained on FRP-reinforced structural members. However, most existing research focuses on the insertion of FBG sensors into bar-shaped FRPs, and there is a lack of studies that analyze the details for an FRP strip combined with FBG sensors. In this regard, this paper seeks to develop a reinforcement for an NSM (near-surface-mounted) retrofit in which an optical fiber with an FBG sensor is combined with FRP strips. For this, a series of experiments were performed to find the adhesive strength of optical fiber-epoxy-FRP interfaces, the tensile strength of the FBG sensor part of optical fiber with a reflection lattice, and the sensing performance depending on the adhesion length between the optical fiber and the FRP strips. As a result of the study, the adhesion length not less than 20 mm in one direction from the center, with a total adhesion length of 40 mm, needs to be secured when the optical fiber with an FBG is attached and fixed between the two FRP strips with epoxy. In addition, it is expected that the proposed model can be used to properly predict the strain transfer of an FRP strip with a fiber optic sensor and can also be utilized when determining optimum dimensions.

scholarly journals Application of the Microclamped Fiber Bragg Grating (FBG) Sensor in Rock Bolt Support Quality Monitoring

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Xinxin Guo ◽  
Bo Wang ◽  
Zhenyu Wang ◽  
Wei Yu ◽  
Zhenwang Ma ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Mechanical Performance ◽  
Rock Bolt ◽  
Theoretical Formula ◽  
Bragg Grating ◽  
Test Sensitivity ◽  
Fbg Sensor ◽  
Measured Strain ◽  
Fbg Sensors ◽  
Rock Bolt Support

The force-measuring rock bolt instrumented with bare fiber Bragg grating (FBG) sensors are generally factory-fabricated. To enable users to fabricate a force-measuring rock bolt by themselves, the microclamped FBG sensor is proposed to replace the encapsulated bare FBG sensor. A theoretical formula of strain sensitivity is also established. The strain sensibility measured by indoor calibration is consistent with the theoretical one, indicating that the microclamped FBG sensor can measure strain accurately. Besides, the measured strain sensibility coefficient (wavelength difference/strain) matches the theoretical values, making the installed microclamped sensor free from the need for recalibration and proving the installation method to be reliable. Also, the test sensitivity can be adjusted as needed. The instrumented rock bolt with microclamped FBG sensors shows great mechanical performance in the field test, awaiting further usage in applications.

scholarly journals Intensity and Wavelength Division Multiplexing FBG Sensor System Using a Raman Amplifier and Extreme Learning Machine

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yibeltal Chanie Manie ◽  
Run-Kai Shiu ◽  
Peng-Chun Peng ◽  
Bao-Yi Guo ◽  
Mekuanint Agegnehu Bitew ◽  
...  
Keyword(s):  
Extreme Learning Machine ◽  
Wavelength Division Multiplexing ◽  
Sensor System ◽  
Bragg Wavelength ◽  
Wavelength Division ◽  
Raman Amplifier ◽  
Fbg Sensor ◽  
Transmission Distance ◽  
Fbg Sensors ◽  
Learning Machine

A fiber Bragg grating (FBG) sensor is a favorable sensor in measuring strain, pressure, vibration, and temperature in different applications, such as in smart structures, wind turbines, aerospace, industry, military, medical centers, and civil engineering. FBG sensors have the following advantages: immune to electromagnetic interference, light weight, small size, flexible, stretchable, highly accurate, longer stability, and capable in measuring ultra-high-speed events. In this paper, we propose and demonstrate an intensity and wavelength division multiplexing (IWDM) FBG sensor system using a Raman amplifier and extreme learning machine (ELM). We use an IWDM technique to increase the number of FBG sensors. As the number of FBG sensors increases and the spectra of two or more FBGs are overlapped, a conventional peak detection (CPD) method is unappropriate to detect the central Bragg wavelength of each FBG sensor. To solve this problem, we use ELM techniques. An ELM is used to accurately detect the central Bragg wavelength of each FBG sensor even when the spectra of FBGs are partially or fully overlapped. Moreover, a Raman amplifier is added to a fiber span to generate a gain medium within the transmission fiber, which amplifies the signal and compensates for the signal losses. The transmission distance and the sensing signal quality increase when the Raman pump power increases. The experimental results revealed that a Raman amplifier compensates for the signal losses and provides a stable sensing output even beyond a 45 km transmission distance. We achieve a remote sensing of strain measurement using a 45 km single-mode fiber (SMF). Furthermore, the well-trained ELM wavelength detection methods accurately detect the central Bragg wavelengths of FBG sensors when the two FBG spectra are fully overlapped.

Investigation on Temperature Compensation of Fiber Bragg Grating Sensors for Hull Monitoring

2018 ◽  
Author(s):  
Ruiqi Ma ◽  
Guoqing Feng ◽  
Huilong Ren ◽  
Peng Fu ◽  
Shuang Wu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Fiber Bragg Grating ◽  
Temperature Compensation ◽  
Compensation Method ◽  
Bragg Grating ◽  
Theoretical Derivation ◽  
Temperature Changes ◽  
Hull Girder ◽  
Fbg Sensor ◽  
Fbg Sensors

Hull monitoring system with Fiber Bragg Grating (FBG) sensors increasingly receives people’s attentions. However, for the ship hull monitoring, the deformation of hull girder changes a lot as is subjected to a huge temperature variation. Therefore, the compensation method with only FBG temperature self-correction is not suitable for the hull monitoring sensors because no material thermal expansion effects are reasonably included. In this paper, the new compensation method of hull monitoring FBG sensor based on the sensor theory with both FBG temperature self-correction and steel thermal expansion effects correction is studied. The coupled compensation method suitable for hull monitoring sensor is obtained by theoretical derivation. As the comparison, the coupled compensation experiment was carried out. The results show that the relative error under the temperature compensation method is large in the case of drastic strain and temperature changes, and the correction results of the tested method will be closer to the true level.

scholarly journals Understanding the Impact of Machine Learning Models on the Performance of Different Flexible Strain Sensor Modalities

2021 ◽  
Vol 8 ◽  
Author(s):  
Brett C. Hannigan ◽  
Tyler J. Cuthbert ◽  
Wanhaoyi Geng ◽  
Mohammad Tavassolian ◽  
Carlo Menon
Keyword(s):  
Machine Learning ◽  
Mean Squared Error ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Signal Amplitude ◽  
Electrical Signal ◽  
Gauge Factor ◽  
Piezoresistive Sensor ◽  
Fibre Strain ◽  
The Impact

Fibre strain sensors commonly use three major modalities to transduce strain—piezoresistance, capacitance, and inductance. The electrical signal in response to strain differs between these sensing technologies, having varying sensitivity, maximum measurable loading rate, and susceptibility to deleterious effects like hysteresis and drift. The wide variety of sensor materials and strain tracking applications makes it difficult to choose the best sensor modality for a wearable device when considering signal quality, cost, and difficulty of manufacture. Fibre strain sensor samples employing the three sensing mechanisms are fabricated and subjected to strain using a tensile tester. Their mechanical and electrical properties are measured in response to strain profiles designed to exhibit particular shortcomings of sensor behaviour. Using these data, the sensors are compared to identify materials and sensing technologies well suited for different textile motion tracking applications. Several regression models are trained and validated on random strain pattern data, providing guidance for pairing each sensor with a model architecture that compensates for non-ideal effects. A thermoplastic elastomer-core piezoresistive sensor had the highest sensitivity (average gauge factor: 12.6) and a piezoresistive sensor of similar construction with a polyether urethane-urea core had the largest bandwidth, capable of resolving strain rates above 300% s−1 with 36% signal amplitude attenuation. However, both piezoresistve sensors suffered from larger hysteresis and drift than a coaxial polymer sensor using the capacitive strain sensing mechanism. Machine learning improved the piezoresistive sensors’ root-mean-squared error when tracking a random strain signal by up to 58% while maintaining their high sensitivity, bandwidth, and ease of interfacing electronically.

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