Search

A hydrogen and humidity simultaneous measurement system based on an integrated FBG sensor is proposed. Experimentally results indicate the sensor shows a high degree of hydrogen discrimination ranging from 100ppm-8000ppm and a high degree of humidity discrimination ranging from 20% - 80%, along with the high performance of anti-mutual interference of hydrogen and humidity.

Fiber Bragg grating (FBG) sensors are obviously attractive for many prominent advantages, such as strong antielectromagnetic interference ability, long transmission distance, and fast transmission speed. Due to these advantages, FBG sensors can be used for the health monitoring of high-voltage transmission lines. The FBG sensor can not only ensure the security of the transmission lines, but can realize real-time monitoring, which can effectively prevent serious accidents caused by rust breakage of overhead steel strand. In this paper, a new type of corrosion sensor based on FBG was developed to monitor and evaluate the degree of corrosion damage of the steel strand. To verify the performance of the FBG corrosion sensors, an electrochemical corrosion accelerated experiment was conducted on an actual steel strand. The experimental results show that the FBG corrosion sensors have a large measurement range of steel strand corrosion rate, and can monitor steel strand corrosion expansion damage in early stage effectively. The FBG corrosion sensor has practical application value in the field of electricity transmission engineering.

In this study, two fiber Bragg grating sensors are multiplexed using time division multiplexing. The fiber Bragg gratings are setup in a dual bus configuration and the sensor signals are detected using a transmit-reflect detection system. The results demonstrate that both the transmitted and reflected signals from both fiber Bragg gratings can be resolved when the sensors are separated by a sufficient distance.

In this process, the processing flow of fiber Bragg grating (FBG) embedded carbon fiber reinforced composites are prepared by means of pressurized film forming and end-surface elicitation. Firstly, the development of composites in aerospace field is introduced. Then, according to the principle of FBG sensor, a scheme for embedding fiber grating into carbon fiber composites is designed. There are three key steps involved in this process, namely, laying the bare fiber parallel to the carbon fiber cleavage direction, applying the end-surface elicitation method with the use of stainless steel thin tubes and Teflon fine tubes for protection, and pasting the rubber strip tile on the end to prevent the curing of the fiber break. After processing, a 260x60x3mm surface intact product is made according to the design scheme. There is no deformation in Carbon fiber surface and the end-surface is intact.

Long time lasted micro vibration will easily cause the looseness of bolts. It is critical for the health and safety monitoring of bolt looseness. Although many remarkable bolt looseness detection approaches already been developed in recent years, it is still difficult to the quantitatively evaluate the bolt degradation without do any harm to the bolt. In this article, a FBG (Fiber Bragg Grating) embedded smart washer was proposed to monitor the looseness of bolt connection and the theory analysis were induced to verify the linear tendency of smart washer annular strain. Two experiments were carried out to verify the analysis: first of all, the relationship between applied torque and bolt tension were investigated. A smart bolt which made by embedding FBG sensor into the bolt was used in the specimen and the experiment result indicates that bolt axial tension is linearly with applied torques which also consistent with previous researches. Then, the experiment which fabricated with smart washer and smart bolt was implement. The linear relationship between pre-load change and the wavelength increment was obtained. The analytical and experimental results both demonstrate that the proposed novel approach in this study is very sensitive to the bolt pre-load degradation and it is robust in monitoring the blot looseness.

The Department of Transportation classifies a vehicle depending on the number of axles and the space between them (wheelbase). Vehicle classification accuracy depends on the accuracy in estimating the speed and the wheelbase. In this study, a three-dimension Glass Fiber-Reinforced Polymer packaged Fiber Bragg Grating sensor (3D GFRP-FBG) is introduced for vehicle speed and wheelbase estimation. The experimental results show the ability of the sensor to estimate the speed and the wheelbase of a reference vehicle, with an accuracy of 95% or higher.

In this work, Pd/Pt material based fiber Bragg grating (FBG) sensors has been proposed for detection of hydrogen sulfide gas. Here, characteristics of FBG parameters were numerically calculated and simulated. The variation in reflectivity based on refractive index has been shown. The reflectivity of FBG can be varied when refractive index is changed. The proposed sensor works on very low concentration i.e., 0% to 1%, which has the capability to detect in the early stage.

Authors of this article focused on the analysis of the influence location of the fiber-optic sensor on the measurement and determination the heart rate of the human body. The sensor uses a Fiber Bragg Grating (FBG) and is encapsulated in the polymer polydimethylsiloxane (PDMS). The combination of fiber-optic technology and its encapsulation in a polymer PDMS allows the use of the sensor e.g. in magnetic resonance environments (MRI). Among currently solved doctors requirements belongs field focusing on the study of hyperventilation and panic attacks of patients during MRI examination due to their very frequent occurrence. Proposed FBG sensor can help doctors to predict (based on heart rate) hyperventilation and panic attacks of patients during MRI examinations. For the most accurate determination of the heart rate, it is necessary to know the influence location of the sensor on the human body. The sensor functionality and analysis of the sensor placement on the heart rate has been verified by a series of real experimental measurements of test subjects in laboratory environment.

This article focuses on the analysis and verification of a non-invasive fiber Bragg grating (FBG) sensor used for the monitoring of a patient`s heart rate (HR) and respiratory rate (RR) in a magnetic resonance environment (MRI). Measuring heart and respiratory rate were carried out on a group of five volunteers with their written consent during MRI examinations. The type of the scanner used in the experiment was GE Signa HDxt 1.5T. The benefit of this article lies in the design of a sensor in the form of a sensor pad. The sensor is placed beneath a patient`s body lying supine. The purpose is to increase and improve the patient`s safety as well as to help doctors to predict panic and hyperventilation attacks of patients during MRI examinations. Provided Bland-Altman statistical analysis demonstrates the heart and respiratory rate detection with a satisfactory accuracy for all five volunteers.

At present, Spacecraft manufacturing face with high adventure for its complicate structure, serious space environment and not maintained on orbit. When something wrong with spacecraft, monitoring its health state, supply health data in real time would assure quickly locate error and save more time to rescue it. For FBG sensor can distributed test several parameters such as temperature, strain, vibration and easily construct net. At same time, it has more advantages such as ant-radiate, anti-jamming, rodent-resistant and with long lifetime, which more fit for applying in space. In this paper, a spacecraft health monitor system based on FBG sensors is present, Firstly, spacecraft health monitor system and its development are introduced. Then a four channels FBG demodulator is design. At last, Temperature and strain detecting experiment is done. The result shows that the demodulator fully satisfied the need of spacecraft health monitor system.

Authors of this article focused on the use of fiber-optic technology for monitoring heart and respiratory rate of the human body. The article describes an innovative method of encapsulating fiber Bragg grating (FBG) into polymer polydimethylsiloxane (PDMS) and comparison of this measuring probe with an FBG sensor glued on the plexiglass pad. The team of authors offers a solution which is basically focused on the monitoring of long-term ill patients with a minimum of physical movement load. Real data were acquired from a group of 10 volunteers with their written consent in the laboratory environment. Acquired data was compared by the Bland-Altman method.

Technology fiber Bragg grating (FBG) belongs to the most widespread fiber optic sensors. It used for measuring a large number of chemical and physical quantities. Immunity to el ectromagnetic interference, small size, high sensitivity and principle information encoding about the measured value to the spectral characteristics cause usability of FBG sensors in medicine for monitoring vital signs such as heart rate, blood pressure, temperature or respiration. An important factor in this area is the use of an inert material for the Bragg gr atings encapsulation. An interesting choice is the elastomer polydimethylsiloxane (PDMS). PDMS is optically clear, general inert, non-toxic and non-flammable. The material commonly used for biomedical and medical applications. Experimental results presented in this paper describe the creation of prototype FBG sensor for the heart rate monitoring of a human body. The sensor is realized by Bragg grating encapsulated into polydimethylsiloxane. The FBG sensor is part of the elastic contact strap which encircles the chest of the patient. This chest expansion leads to a spectral shift of the reflected light from the FB G. The research based on the monitoring of eight different test persons. Heart rate meas urements were compared with a reference signal ECG and analyzed objectively by th e Bland-Altman statistic.

The surface-bonding method of the fiber Bragg grating(FBG) sensor is easier to handle than embedding method. However surface bonded FBG sensors have the limitation of the signal characteristics being affected by the bonding layer. In this study, the effects of the bonding length on the surface installed FBG sensor signal characteristics under various load types were empirically investigated. To evaluate the stability of the signal characteristics of the FBG sensors, the strain transfer rate and the multiple peaks ratio of the reflected spectrum were calculated and compared. From the experimental results, the strain transfer ratio and multiple peaks ratio varied because of the different strain gradients formed depending on the applied load type. Therefore, it was found that the effective bonding length for respective load types need to be determined to get a stable signal from the surface bonded FBG sensors.

We investigate the sensitivity improvement of fiber Bragg grating (FBG) sensors based on the optical attenuation-based weak value amplification (WVA). We successfully enhance the strain sensitivity of the FBG sensor based on the proposed WVA. The amplification factor (A) controlled by the optical attention is optimized to improve the sensitivity of the FBG sensing probe. The strain sensitivity of the FBG sensor using the proposed attenuation-based WVA is successfully enhanced by a factor of 2.73 compared with that without the WVA.

The curing process of epoxy resin was monitored real-time by using embedded fiber Bragg grating (FBG) sensor. The resin was cured at room temperature 24°C for 24 hours. The curing monitor test showed that the temperature inside the resin went up quickly at the first 70 minutes. Then the temperature increased slowly till 120 minutes. Afterward, the central wavelength decreased which indicated two stage of curing, i.e. temperature reduction and curing shrinkage. Furthermore, the cured resin sample under tensile load was studied. Strain gauges were applied in order to evaluate the FBG sensor. Experimental results showed that difference existed between the mentioned sensors.

Fibre Bragg Grating (FBG) sensors are increasingly being used on a wide range of civil, industrial and aerospace structures. The sensors are created inside optical fibres (usually standard telecommunication fibres); the optical fibres technology allows to install the sensors on structures working in harsh environments, since the materials are almost insensitive to corrosion, the monitoring system can be positioned far away from the sensors without sensible signal losses, and there is no risk of electric discharge. FBG sensors can be used to create strain gages, thermometers or accelerometers, depending on the coating on the grating, on the way the grating is fixed to the structure, and on the presence of a specifically designed interface that can act as a transducer. This paper describes a test of several different FBG sensors to monitor an high pressure pipe that feeds the hydraulic actuators of a 6 degrees-of-freedom shaking table at the ENEA Casaccia research centre. A bare FBG sensor and a copper coated FBG sensor have been glued on the pipe. A third sensor has been mounted on a special interface to amplify the vibrations; this last sensor can be placed on the steel pipe by a magnetic mounting system, that also allows the its removal. All the sensor are placed parallel to the axis of the pipe. The analysis of the data recorded when the shaking table is operated will allow to determine which kind of sensor is best suited for structural monitoring of high pressure pipelines. © 2017 SPIE.

Applications of composite materials in aerospace structures is increasing due to the outstanding properties, however, monitoring such composite structures exposed to harsh environments is still a posing issue. Low Earth orbit space structures are exposed to property degradation and damage from high-degree vacuum, ultraviolet radiation, thermal cycling, and atomic oxygen attack which are detrimental to composite materials. In this study, FBG sensors for embedding in CFRP composite plates in different thickness locations to provide health and damage monitoring of the material exposed to such environments regarding the overall health of the material with a focus on the exposed surface are explored in comparison to conventional FBG sensors.

To enrich the sensing mechanism of the FBG sensors, the cantilever FBG sensor is taken as an example to analyze the effect of the deflection on the embedded stress distribution and structure parameters of the FBG, and a widely applicable analysis method is thus proposed. Models of the single-core and multi-core FBG sensor are built by the proposed method and a modified transmission matrix method is utilized to simulate the built models. The lateral resolution of the multicore FBG sensor is proved to be 1500 times higher than the single-core FBG sensor. Simulation results of the proposed models indicate that this approach is tally with the experiment of other researches, and it can be used to analyze the performance of the designed sensors, such as spectrum signal and resolution, or as a guide of designing FBG sensors.

Space deployable mechanisms are widely used, important and multi-purpose components in aerospace fields. In order to ensure the mechanism in normal situation after unfolded, detecting the deformation caused by huge temperature difference in real-time is necessary. This paper designed a deployable mechanism setup, completed its distributed deformation measurement by means of fiber Bragg grating (FBG) sensors and BP neural network, proved the mechanism distributed strain takes place sequence and FBG sensor is capable for space deployable mechanisms deformation measuring.

The FBG sensor has globally been commercialized in various fields that is actively applied in Korea as well. Especially it is widely used as a structural monitoring sensor in civil engineering and construction structures due to its advantages including electrical stability, chemical stability and multiplexing. This report aims to introduce safety inspection of the FBG sensor in respect of radioactivity which has been applied to a silo structure for radioactive waste disposal as an example.

The large span and heterogeneous components of multi-layered pavement structure usually bring about stochastic damage, and many modern approaches, such as ground penetrating radar, integral imaging and optical fiber sensing technology, have been employed to detect the degeneration mechanism. Restricted by the cost and universality, novel elements for pavement monitoring are in high demand. Optical fiber sensing technology for high sensitivity, long stability, anti-corrosion and resistance to water erosion then is considered. Therefore, a movable FBG sensor located in flexible pipe is developed, which has long stroke inside inner wall of the hollow pipe, and a full-scale shape of the structure could be sketched just with one FBG. Theoretical and experimental methods about establishing the relationship between wavelength variable and curvature have been provided, and function about reconfiguring the coordinate is converted to a mathematic question. Move over, transfer error modification has been taken into account for modify related error. Multi-layered pavement model embedded with this sensor will be accomplished to inspect its performance in later work. The work in the paper affords a feasible method for shape monitoring and would be potentially valuable for the maintenance and inverse design of pavement structure.

We demonstrated a simple method for temperature-independent refractive index measurement by use of two cascaded fiber Bragg gratings fabricated in single-mode fiber and microfiber, respectively. The reflective peaks of the two FBGs exhibit almost identical temperature sensitivity of 10.1 pm/°C and different responses to ambient refractive index. Based on the differential measurement method, of the issue of temperature cross-sensitivity for FBG sensors is solved. The refractive-index sensitivity of the sensor is 17.22 nm/RIU when the diameter of microfiber is 6.5 μm.

A novel real-time monitoring system based on Fiber Bragg Grating (FBG) sensor has been developed to detect chatter in boring process. In the system, a boring bar with large length-to-diameter ratio (FSTUP3225R/L-16S) was the test subject. The FBG sensor was installed on the surface of the boring bar with the length of 225mm. A classical strain gauge was employed to measure the vibratory strain and compare the results with the ones from FBG sensor. The measurements were carried out using various cutting parameters to obtain the desired chatter phenomenon. The analysis of the experimental data was verified the chatter happened during the deep hole boring. Comparison between the experimental results from two kinds of sensors demonstrated that the measurement technique could be used to detect the dynamic strain, as well as the permitting one to research the method to identify boring chatter on-line be using optical fiber sensor system.

Structural Health Monitoring Systems based on embedded FBG sensors, to identify damage conditions, are largely dependent on the spectral distortion of the sensors. The uneven stress gradient occurring along the grating of FBG sensors, due to damage inside composite structures can be estimated by analysing significant changes that appear in the FBG response spectra. However, the stochastic nature of the distorted shape of the FBG spectra makes it difficult to interpret and quantify the existing damage at the location of the FBG sensors. There are several indexing methods proposed by researchers. We have previously presented a novel concept of the “Distortion Index (DI)” which is defined using distorted spectra of FBG sensors. It was observed that the DI increases with the increase in damage size. The Distortion Index (DI) is introduced to create a correlation between the damage and the distortion of the response spectra of a FBG sensor. This index provides the ability to generalise the distortion of FBG spectra for a particular structure. The index can be used to quantify the damage in the structure relative to its original condition, which can be the condition of structure during a regulated time, i.e. a month uninterrupted operation or first hours in operation, of a structure can be used as no damage condition. In this paper we discuss the application of distortion index and comparison with available several other indexes.

We present a solid-state FBG array interrogator and multiplexer capable of determining absolute FBG wavelengths and of providing high-speed, high-resolution static and dynamic measurements. Using a described procedure, deployable on multiplexing passive-interferometric schemes, the system is able to determine initial sensor wavelengths and thereafter track wavelength changes with interferometric resolution. The scheme allows high-resolution interrogation of FBG sensor arrays to be applied to many industrial applications, where previously the lack of combined absolute and quasi-static wavelength measurement precluded the use of interferometric techniques. Using a preliminary laboratory embodiment, we demonstrate a wavelength determination accuracy of

It is the aim of this paper to present the design of a sensor system based on fiber Bragg gratings (FBG) for the strain monitoring of an adaptive trailing edge (ATE) device. Some of the activities herein showed comes from developments inside the project SARISTU (EU-FP7), funded by the European Union inside the VII Framework Programme and focused on smart aircraft structures. Because the TE is immerged into 3D structural and aerodynamic fields, the sensor system network should have chord- and span-wise features. The ATE device will be equipped with a shape monitoring system using a widely distributed sensors based on fiber optic (FO) elements herein referred to, mainly with the aim of reducing the number of channels (then expense, complexity, etc.). In what follows, the mathematical modelling of a sensor system concept based on FBG is applied to evaluate the chord-wise strain of a trailing edge device. A hinge rotation detection capabilities based on strain measurements is presented. The detection and process of data concerning the in-flight ATE local deformation are necessary to reconstruct the shape produced by the action of a dedicated actuation system.

The proposed desensitized encapsulation structure solved the problem that more than 5500μe test range for FBG sensor. The single steel wire with proposed FBG sensor tension test in laboratory before and after fatigue experiment showed the rationality and reliability of sensor structure. A scheme using desensitized encapsulation FBG sensor to fabricate smart cable which was compatible with production process of parallel steel wires cable was designed. The specimen cable tension test verified sensors high survival rate of the design scheme and good long-term precision after fatigue experiment. Also the actual application of smart cable was tested by one bridge during the construction and operation stage.

The strain sensitivity of FBG-based strain sensors that had been inscribed into three different types of optical fibers were determined for both conditions, for fibers that were glued on a specimen and for free, bare fibers, i. e. fibers that were not bonded to a structure at the location of the FBG. The influence of the gluing technique on the strain sensitivities of the FBG sensor elements was investigated by comparing the strain sensitivities of a multitude of attached and free sensor elements on a statistical basis. A good agreement between the strain sensitivities of free and attached fibers was achieved, which shows the high quality of the gluing method employed.

Corrosion of steel in structures has become a major cause of structural degradations. Corrosion detection and monitoring are necessary for evaluation of structural service conditions. A novel FBG based sensor for steel corrosion detection and monitoring is developed previously. In this paper the sensor performances are evaluated by comparing to the corrosive rate of rebars in the corrosive environments. The correlation between the wavelength shifts of the sensor and the corrosive depth is established. It is proved that the sensor responses successfully to the occurrence of rebar corrosion, which shows the promising feasibility of applying the sensor for corrosion indicator.

We used a bimetallic strip to increase the sensitivity of a fiber Bragg grating temperature sensor. The temperatureinduced deflection of the strip strained the FBG sensor, increasing the Bragg wavelength shift in addition to the temperature-induced one. The total Bragg wavelength shift is about 4 times larger than that of the intrinsic FBG temperature sensor. With experiments in various conditions, the sensitivity characteristics according to the bimetal parameters were analyzed and the feasibility of the suggested sensor has been shown

In this paper, we report our recent work in an application of fiber Bragg grating (FBG) sensors in progressive failure monitoring of E-glass/vinylester top-hat stiffener (THS) composites. FBG sensor arrays were embedded at strategic points within the THS to monitor the onset and progress of failure modes as the THS undergone a transverse loading. Techniques to embed FBGs in-situ during composite structure fabrication are developed. Our experiments demonstrated that key structural failure information can be obtained from the analysis and assessment of data, such as average strain, strain gradient and full spectrum measurements, collected by the embedded FBG sensors.

Detecting the possibility of train derailment and preventing the happening of derailment are very important to railway safety affairs. The FBG has the anti-electromagnetic interference, anti-corrosion and strong stability characteristics which make it very practical for high-speed train's safety detection. A quasi-distributed Fiber Bragg Grating (FBG) based strain sensing system for railway derailment detecting is presented in this paper. The FBG sensor system is designed to detect possible factors which may lead to train derailment, such as the speed of train, the max value of coefficient of derailment and off load ratio R. Then there is algorithm to analysis the possibility of train derailment with detected data. The FBG's characteristic of multiplexing make the railway safety networks service becomes possible.

We suggest a spectrometer demodulation method of FBG sensors for the possible uses in wind power generator's blade monitoring. High signal-to-noise ratio outputs and linear demodulation were obtained by combining a fiber laser light source and a spectrometer which used a holographic volume grating and a 512-pixel PD array. Preliminary experimental results are presented to show the feasibility of the suggested FBG demodulation system.

The importance of real-time detection of cable force during stretching construction can hardly be overstated, especially in long-span space cable system. In this paper, a novel approach to monitor the cable structure health using fiber Bragg grating (FBG) sensors was elaborated and applied in monitoring the tensioning process of suspend-cable dome of Dalian Gymnasium under construction. The encapsulated FBG strain sensors were adhered to the anchor to detect the cable force. Calibration tests conducted prior to leaving factory in order to get the cable force sensitivity coefficient were also presented. The monitoring results of stage stretching construction prove that this cable force monitoring method based on FBG sensors has advantages of easy installation, non-destruction to structure and high precision, showing promising potential in cable structure health monitoring.

In the past few years, fiber Bragg grating (FBG) sensors have attracted a lot of interest and there were number of studies on the use of FBG sensors to detect the strain of steelworks. This paper describes the strain sensors based on FBG with different package used for steelwork. Strain distribution of the steelwork is predicted through Finite element analysis. Bare FBG, FBG sensor packaged with steel sheet and resistance strain gauges are set on the same specified location of steel specimen, and load is added on the steelwork by rally machine. Strain values of the steel specimen can be caught by three kinds of sensors when load is stabilized. Then the load added on the steelwork is changed from 0KN to 50KN and back to 0KN, meanwhile the values of strain are recorded respectively. Results of three sensors are compared mutually and are all close to theoretical values provided by FEA.

Many established and recently-introduced optical biosensor concepts rely on the detection of a small wavelength change in response to change of temperature, adhesion of bio-particles, strain, or chemical environment. Special coatings are used to sensitize them to specifically bound molecules (e.g., biomarkers). We describe a compact and fast wavelength monitor that can resolve sub-pm wavelength changes. The unit was demonstrated by reading out a FBG sensor and can resolve wavelength changes as small as 50fm with a bandwidth of more than 100Hz.

In this paper, to investigate a method improving high temperature response characteristics, the high temperature sensing properties of fiber Bragg gratings packaged by the red copper and cuprum and aluminum respectively were studied. The results indicate that the response characteristics of FBG have very good linearity, and the linearity of FBG packaged by aluminum is best, but its response time is slower because of lower heat conductivity of packing material, and that higher thermal expansion coefficient of packaging base material can effectively reduce the nonlinearity of FBG sensor in high temperature environment. At last, a method improving the temperature sensitivity of FBG sensor and reducing FBG's nonlinear response versus temperature was presented, and packaging material is selected according to response time versus temperature change.

Over the last few years, fiber Bragg grating (FBG) sensors have attracted a lot of interest and they are being used in various applications. This paper describes the FBG sensors used for strain monitoring of bogie and other steelworks. FBG sensors and resistance strain gauges are set on different position of steel girder, and weight is loaded on the steel girder. Strain value of the steel girder can be caught by two kinds of sensors when weight loaded is changed. Result of experiment shows that strain value obtained by resistance strain gauges and FBG sensor is coinciding. There is a linear correlation between value of strain and the weight loaded on the steel girder. FBG sensors with different encapsulations are set on bogie by acrylic plastic materials in order to monitor its dynamic strains. When sinusoidal load with its frequency from 0.15Hz to 2Hz was set on the bogie, FBG sensor system with data sampling rate of 20Hz were used to monitoring the dynamic strains. Strain data caught by FBG sensor system can offer accurate description of dynamic strain, and value of strain provided by FBG sensor suits theoretical values well. The experimental observations show that FBG sensors can be set on steelworks easily, and can monitor both static strain and dynamic strains well.

Being an important bridge engineering structural strengthening manner, external prestressing method usually makes steel strand which is one of the most widely used member in external cable bear large strain in construction and operating stage. By means of directly testing structural strain to monitor the mechanical condition and prestressing loss of steel strand is a great challenge for civil engineers. In order to exert the advantages of FBG sensing technology, study FBGbased bridge external prestressing test method, achieve the FBG-based prestressing loss monitoring, in this paper, the difficulties that use FBG to test structural large strain were analyzed and a FBG-based monitoring strategy was elicited. In order to verify the proposed method, a real bridge strengthening engineering paradigm was given. The monitoring results showed that the proposed strategy not only met the requirement for structural large strain testing during the whole construction process, but also the intact FBG sensor still played a role in the subsequent prestressing loss monitoring.

An extensive model test program had been carried out to investigate the issues of ice loading on bridge pier model. This paper investigated design principle of three kinds of FBG sensor modules, including FBG-based displacement sensor module, FBG-based strain sensor module and FBG-based force sensor module. A series of calibration tests of all FBG sensors had been made to detect the sensitivity of FBG sensor modules previously. There were 12 FBG-based sensors applied to monitor the failure progress and to predict the cracking inside the bridge pier model. The results of the ice loading tests proved that the FBG-based sensor had many advantages, characterized by its small size, high precision, easier installation, water resistance and cold resistance, demonstrating promising potentials in cracking and failure monitoring of bridge pier model.

A human physiological parameters intelligent clothing is researched with FBG sensor technology. In this paper, the principles and methods of measuring human physiological parameters including body temperature and heart rate in intelligent clothing with distributed FBG are studied, the mathematical models of human physiological parameters measurement are built; the processing method of body temperature and heart rate detection signals is presented; human physiological parameters detection module is designed, the interference signals are filtered out, and the measurement accuracy is improved; the integration of the intelligent clothing is given. The intelligent clothing can implement real-time measurement, processing, storage and output of body temperature and heart rate. It has accurate measurement, portability, low cost, real-time monitoring, and other advantages. The intelligent clothing can realize the non-contact monitoring between doctors and patients, timely find the diseases such as cancer and infectious diseases, and make patients get timely treatment. It has great significance and value for ensuring the health of the elders and the children with language dysfunction.

Fibre Bragg gratings are promising sensors for medical and bioengineering applications, mainly because of their small dimensions and chemical inertness. Although few examples of such applications are published up to date, we present results that show the expected potential for FBG sensor applications in biomechanical engineering.

A fiber Bragg grating (FBG) sensors network in the roadbed temperature monitoring system in Qinghai-Tibet railway is presented. This sensor network is composed of FBG sensor chains embedded in the roadbed, slave optical cables, work stations which include the FBG sensor interrogator and the optical router, master optical cables, and center workstation. We give the primary experimental results of this sensor network in monitoring the roadbed temperature of the railway at DK0985+000 near Chumar River. The te mperature data was collected after a m onth when the temperature field in the monitoring hole became stable. This experiment had been car ried out for more than one year. The FBG sensor network has successfully measured the temperature in the roadbed with an accuracy of 0.1 centigrade. Furthermore, the experimental result shows the stability and reliability of the FBG sensor network in the harsh environment of Qinghai-Tibet plateau. The prospect of the FBG sensor network in monitoring other parameters in the Qinghai-Tibet plateau is also presented. Keywords: FBG, sensor, network, railway

In this paper, a novel 3D strain FBG sensor based on cylinder structure is reported. In our experiment, we used 3 FBGs as sensing element and fixed them on the side of the cylinder according to 120° angle intervals. Based on the physical and mathematics principle, theoretical derivations and experiment setup were also showed. In application, this sensor would have a good prospect.

A FBG-based dynamic strain sensor system, whose responding frequency and resolution can be high as 16Hz and ~1μe respectively, is described and the system is applied to monitor the dynamic strain of Como Railway Bridge in Australia. The results of one-month long measurement show that the system can figure out all dynamic strain caused by passed trains and also prove the stability of the sensor system.

There is a growing demand for lightweight structures in aircraft systems for energy and cost savings. The authors have therefore continued development of the Highly Reliable Advanced Grid Structure (HRAGS) with the aim of application of the same to aircraft. HRAGS is provided with health monitoring functions that make use of Fiber Bragg Grating (FBG) sensors in advanced grid structures, which have been the focus of attention in recent years as lightweight structures. It is a new lightweight structural concept that enables lighter weight to be obtained while maintaining high reliability. This report describes the tests and evaluation of the Proto System conducted to verify experimentally the concept of the highly reliable advanced grid structure. The Proto System consists of a skin panel embedded with 29 FBG sensors and a wavelength detection system. The artificial damage to the skin panel of the specimen was successfully detected by comparing the strain distributions before and after the introduction of the damage measured by FBG sensors. Next, the application of HRAGS to the wing tip was studied. The results of the studies above are reported here.

This research proposes use of Fiber Bragg Grating (FBG) sensors to measure and monitor patient body temperature non-intrusively on a Smart Bed Sheet. The use of FBG sensors allows smart bed sheet to have the look and feel of an ordinary conventional bed sheet since FBG sensors have a very thin and light linear geometry. Additionally, they are dielectric in nature, and have a total immunity to electromagnetic and RF interferences. Recent developments in FBG research have made these sensors considerably inexpensive but very reliable. Simple signal processing techniques can extract very precise temperature from FBG sensors.

It is a great challenge to prevent cracks occurring due to the temperature deviation of inside and exterior of large mass concrete structures during construction. 237 FRP (Fiber Reinforced Polymer)-packaged FBG (Fiber Bragg Grating) temperature and strain sensors have been used to monitor the temperature and strain course of mass concrete structures for construction control of Nanjing 3rd Yangtze Bridge. The practical investigation results show that the FRP-packaged FBG sensors are proper for construction control of mass concrete structures, which show great advantages rather than conventional sensors.