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Railway and train security are very important in preventing service disruption and ensuring quality and safe journeys. Conventional gauges are used in laboratory environments for the strain measurement of rails used in railways. However, the use of these electrical sensors is not practical in long-distance railways. Instead, access to long distance...
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Context 1
... σ is stress, F is force, l is the distance between the supports (100 cm), c is the distance between the rail base and the center of gravity, and I is the rail's moment of inertia. The measurements of the 49E1 rail profile used in this experiment are described in EN 13674-1 standard of Vignole railway rails 46 kg/m and above as indicated in Figure 4. According to EN 13674-1 standard, for 49E1 rail profile, the distance between the rail base and the x-x center of gravity (c) is 7.341 cm, and the rail moment of inertia (I) is 1816 cm 4 . ...
Context 2
... σ is stress, F is force, l is the distance between the supports (100 cm), c is the distance between the rail base and the center of gravity, and I is the rail's moment of inertia. The measurements of the 49E1 rail profile used in this experiment are described in EN 13674-1 standard of Vignole railway rails 46 kg/m and above as indicated in Figure 4. According to EN 13674-1 standard, for 49E1 rail profile, the distance between the rail base and the x-x center of gravity (c) is 7.341 cm, and the rail moment of inertia (I) is 1816 cm 4 . When these values are put in Equation (13), the following equation between the force and stress is obtained; The strain is obtained using Equation (3) (Hooke's law) with the stress value obtained from the abovementioned equation according to the force applied to the rail. The elastic modulus for the rail is taken as 210 GPa. Thus, the relation between stress and strain for the rail is expressed as ...
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Citations
... In previous studies, scholars usually install FBG strain sensors on the rail surface to monitor the vertical train load by measuring the strain response during the passage of the train and combining the strain data with the calibration of field data [44][45][46], as shown in Fig. 1. However, during long-term service, the sensors are exposed to the external environment and might suffer from high-pressure shocks, mechanical damage from passing trains, and damage due to rust, corrosion, or changes in the shape of the rails. ...
... The fiber-optic vibration sensor is attracting attention because of its lightweight, simple structure, antielectromagnetic interference, and intrinsic explosion-proof characteristics, which can effectively solve the problem of long-term work in harsh working conditions. At present, the reported fiber-optic vibration sensor structures mainly include Fabry-Perot interferometer (FPI) [13][14][15], fiber Bragg grating (FBG) [16][17][18], Mach-Zehnder Interferometer (MZI) [19][20][21], etc. Yu et al proposed a fiber-optic vibration sensor with FPI using Kagome structured hollow-core photonic crystal fiber, with a single-frequency signal measurement range of 1 Hz to 20 kHz, but the sensor output signal would be slightly distorted [22]. Weng et al designed an FBG fiber optic seismic sensor, which consists of an L-shaped cantilever beam, a mass block, and a diaphragm. ...
With their long transportation distance and high productivity, belt conveyors are characterized as the main equipment for bulk material transportation in coal mines and other key industries. However, its speed detection method has always been an engineering challenge under harsh working conditions. In this work, the elastic-optical effect of the polarization-maintaining fiber is used to design a fiber ring laser vibration sensing system based on a fiber-optic Sagnac interferometer vibration sensor and its packaging structure. The vibration detection is achieved by detecting the change in optical power at the working wavelength, and the belt conveyor speed measurement is completed by detecting the vibration frequency. With such a method, the belt conveyor speed measurement obtained a relative error of less than 1.88%. The proposed method bears the characteristics of anti-electromagnetic interference, intrinsic explosion-proof, and adapts to the harsh smoke and dust working environment, which has a wide range of application prospects in the fields of engineering, machinery, security, etc.
... On the other hand, MMT, shown in Figure 4b, is a specially designed and equipped train for track maintenance tasks and has been described as a "workshop on wheels," providing a workplace which is from the sun, Railway track constantly degrades with use. It is subject to the enormous stresses of the lateral and longitudinal forces from trains [44]. Environmental conditions such as heavy rain, extreme cold, snow, scorching heat, etc., accelerate degradation. ...
Inspection and repair interventions play vital roles in the asset management of railways. Autonomous mobile manipulators possess considerable potential to replace humans in many hazardous railway track maintenance tasks with high efficiency. This paper investigates the prospects of the use of mobile manipulators in track maintenance tasks. The current state of railway track inspection and repair technologies is initially reviewed, revealing that very few mobile manipulators are in the railways. Of note, the technologies are analytically scrutinized to ascertain advantages, unique capabilities, and potential use in the deployment of mobile manipulators for inspection and repair tasks across various industries. Most mobile manipulators in maintenance use ground robots, while other applications use aerial, underwater, or space robots. Power transmission lines, the nuclear industry, and space are the most extensive application areas. Clearly, the railways infrastructure managers can benefit from the adaptation of best practices from these diversified designs and their broad deployment, leading to enhanced human safety and optimized asset digitalization. A case study is presented to show the potential use of mobile manipulators in railway track maintenance tasks. Moreover, the benefits of the mobile manipulator are discussed based on previous research. Finally, challenges and requirements are reviewed to provide insights into future research.
... Structural health monitoring, supporting timely detection of damage, and exempting the interruption of the normal operation of a monitored system (e.g., track-vehicle system), has been widely applied to different civil structures [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Examples in railway engineering without the interruption of the normal operation of the train include the interval dynamic analysis of the train-bridge system [23], rail crack identification [24], wheel damage detection [21,25], and track condition monitoring [26][27][28][29][30][31][32][33][34][35][36][37]. ...
... Structural health monitoring, supporting timely detection of damage, and exempting the interruption of the normal operation of a monitored system (e.g., track-vehicle system), has been widely applied to different civil structures [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Examples in railway engineering without the interruption of the normal operation of the train include the interval dynamic analysis of the train-bridge system [23], rail crack identification [24], wheel damage detection [21,25], and track condition monitoring [26][27][28][29][30][31][32][33][34][35][36][37]. The studies on track condition monitoring involve track slab deformation measurement by using computer vision [33,34], dynamic strain and acceleration [27], and displacement measurement [28] by remote sensing, measurement of different parameters (such as stress and sound wave) by using wireless sensor networks [29], deformation measurement by using fiber Bragg grating (FBG) sensors [30][31][32][33], or distributed fiber optic sensors [34,35], track axial force measurement by using FBG sensors and electronic sensors [36], and geometrical rail track condition monitoring by using FBG and Raman distributed temperature sensors [37]. ...
... Examples in railway engineering without the interruption of the normal operation of the train include the interval dynamic analysis of the train-bridge system [23], rail crack identification [24], wheel damage detection [21,25], and track condition monitoring [26][27][28][29][30][31][32][33][34][35][36][37]. The studies on track condition monitoring involve track slab deformation measurement by using computer vision [33,34], dynamic strain and acceleration [27], and displacement measurement [28] by remote sensing, measurement of different parameters (such as stress and sound wave) by using wireless sensor networks [29], deformation measurement by using fiber Bragg grating (FBG) sensors [30][31][32][33], or distributed fiber optic sensors [34,35], track axial force measurement by using FBG sensors and electronic sensors [36], and geometrical rail track condition monitoring by using FBG and Raman distributed temperature sensors [37]. Both fiber optic sensors and piezoelectric sensors are commonly used in SHM. ...
China Railway Track System (CRTS)-II-slab ballastless track is a new type of track structure, and its interlayer connection state is considerably important for the operation safety and ride comfort of high-speed trains. However, the location and multiple influencing factors of interlayer debonding lead to difficulties in monitoring and identification. Here, the research on the design and application of a monitoring scheme that facilitates interlayer debonding detection of ballastless track and an effective indicator for debonding identification and assessment is proposed. The results show that on-site monitoring can effectively capture the vibration signals caused by train vibration and interlayer debonding. The features of the data acquired in the situations with and without interlayer debonding are compared after instantaneous baseline validation. Some significant features capable of obviously differentiating a debonding state from the normal state are identified. Furthermore, a new indicator, combining multiple debonding-sensitive features by similarity-based weights normalizing the initial difference between mutual instantaneous baselines, is developed to support rational and comprehensive assessment quantitatively. The contribution of this study includes the development and application of an interlay-debonding monitoring scheme, the establishment of an effective-feature pool, and the proposal of the similarity-based indicator, thereby laying a good foundation for debonding identification of ballastless track.
... On the other hand, nowadays, fiber optic and FBG sensors have been becoming much more attractive than conventional sensors, becoming widespread, and rapidly replacing electronic and conventional sensors [32,33]. In contrast to their attractions, fiber optic sensors or materials have never been used directly for temperature measurements in incubators. ...
... In contrast to the conventional sensors [24], the properties of all FBG sensors are perfectly similar to each other [22,32] as explained in detail in Section 1 and the previous section. For these reasons, temperature differences between FBG skin and FBG air temperature sensors were 0°C during the time of this test. ...
Incubator is a medical device that provide a climatic environment for a newborn and a preterm infant. In the incubator environment, especially, the temperature significantly increases the survival rate of infants. In this study, the incubator air temperature, temperature uniformity and infant skin temperature were measured and controlled with conventional methods and FBG based temperature sensors, and their results and related literature results were compared among them. To this end, in addition to classical sensors, six FBG sensors were used during the measurements, and very close results were obtained between them (R2 = 0.9989). In addition, since real time monitoring of the FBG bands were ensured with a user-friendly interface, measurement processes have been made more ergonomic. In this way, the insulation required for the measurements is also provided perfectly. Measurement errors caused by conventional sensors’ properties, which are different for each of them, change over/with time, and also change with different values, have been minimized by using this method. Moreover, in case of increasing the number of sensors for multi-point, continuous and real time temperature measurement in conventional methods, some of the problems such as monitoring of these sensors, obstructing or changing the air flow due to the confusions of these sensors and their cables in the incubator cabinet, and following these, control errors caused by these reasons, and difficulties that may be happened during the infant care and resuscitation procedures have been eliminated. Thus, thermoneutrality in closed incubators were also able to validated and assessed fast and more accurately for preterm and neonates.
... For measuring the strain of rails in railways, another work was proposed by Yucel et al. [25], in which the strain in a 49E1 rail type with hardness and quality of R260 was done. The force on the rail was applied through the rail bending test device. ...
Railroads are an important part of India's public transport facilities. Railway services and networks have been emanated as a remarkably resourceful mode of transport to fulfill the continuing requisition for passenger transport and cargo services. The utilization of such systems under extreme working and loading environment makes it highly vulnerable to deterioration and failure. Hence, the Structural Health Monitoring (SHM) of railroad track structures is quite crucial for safeguarding the rail structures, in order to avoid catastrophic mishaps and also considerably decrease the maintenance cost. Today, in structural health monitoring applications, Fiber Optic Sensor (FOS) has indeed found widespread use on account of its intrinsic characteristic advantages, viz reduced size, resistance to electromagnetic interference (EMI) lightweight, corrosion and embedding capacity. FOS enables early diagnosis and
... The liquid level method matched theoretical prediction. Yucel and Ozturk [125] established an experiment with a FBG sensor to measure the strain of rail tracks. A rail bending test device was used to apply force on the rail. ...
In recent years, railway infrastructures and systems have played a significant role as a highly efficient transportation mode to meet the growing demand in transporting both cargo and passengers. Application of these structures in extreme environmental situation under severe working and loading conditions, caused by the traffic growth, heavier axles and vehicles and increase in speed makes it extremely susceptible to degradation and failure. In the last two decades, a significant number of innovative sensing technologies based on fiber optic sensors (FOS) have been utilized for structural health monitoring (SHM) due to their inherent distinctive advantages, such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. Fiber optic-based monitoring systems use quasi-distributed and continuously distributed sensing techniques for real time measurement and long term assessment of structural properties. This allows for early stage damage detection and characterization, leading to timely remediation and prevention of catastrophic failures. In this scenario, FOS have been proved to be a powerful tool for meticulous assessment of railway systems including train and track behavior by enabling real-time data collection, inspection and detection of structural degradation. This article reviews the current state-of-the-art of fiber optic sensing/monitoring technologies, including the basic principles of various optical fiber sensors, novel sensing and computational methodologies, and practical applications for railway infrastructure monitoring. Additionally, application of these technologies to monitor temperature, stresses, displacements, strain measurements, train speed, mass and location, axle counting, wheel imperfections, rail settlements, wear and tear and health assessment of railway bridges and tunnels will be thoroughly discussed.
... Raya uygulanan her bir gerilme değerine karşılık dalgaboyunda oluşan kaymalar incelenerek, lineer regresyon ile dalgaboyu-gerilme ilişkisi hesaplanmıştır. Bu şekilde raya uygulanan kuvvet nedeniyle FBG'de oluşan dalgaboyu değişimleri ve gerilme değişimleri gerçek zamanlı olarak izlenmiştir [5,14]. FBG ile sıcaklık ölçümünde ise termal ortam olarak blok ısıtıcı kullanılmıştır. ...
Fiber Bragg Izgaralar (FBG) yaklaşık 1 cm boyutlara sahip olup, klasik tek modlu fibere kolaylıkla bağlanabilirler. Hassas olmalarına rağmen dış ortam koruma tasarımları ile her türlü ortama kolaylıkla monte edilebilirler. Sıcaklık ve gerilme gibi fiziksel büyüklüklerin değişimleri, doğrusal olarak FBG’lerin merkez dalgaboylarında değişime sebep olmaktadır. FBG algılama sistemlerinde, yansıyan sinyalin merkez dalgaboyunun tespiti en önemli araştırma konularından biri olmaktadır. FBG’nin merkez dalgaboyunun tespiti için farklı yaklaşımlar üzerinde çalışılmakla birlikte, en yaygın yaklaşım sinyalin en yüksek güç değerine karşılık gelen dalgaboyunun merkez dalgaboyu olarak kabul edilmesi yaklaşımıdır. Bu en yüksek güç değerine sahip dalgaboyunu tespit etmek için de farklı yöntemler kullanılmaktadır. Bu yöntemler içerisinde en kararlı sonuç veren yöntem ise Gaussian uyarlama yöntemidir. Bu çalışmada sıcaklık değişimine karşılık FBG’nin merkez dalgaboyunun tespiti için Gaussian uyarlama yöntemi teorik ve deneysel olarak incelenmiştir. Sonuç olarak 5 FBG dizinden sıcaklık ölçümü alınarak, anlamlandırılmış ve sıcaklık algılama sistemi gerçekleştirilmiştir.
... As an emerging technology, optical fiber sensors have attracted increasing attention, because of their immunity to electromagnetic interference, simple structure and compact size [1][2][3]. The strain sensors based on optical fiber technology has been used widely to monitor the health of railways, bridges, airfoils and machine tools [4][5][6][7]. Though the optical fiber made of silicon dioxide with a melting point of approximately 1700 °C has excellent high-temperature endurance, its limited stretchability severely restricts the dynamic range of strain measurement. ...
The large-range and high-sensitivity strain measurement in high-temperature ambiance is a great challenge in engineering applications. Because of the frangibility of the glass material, the traditional optical fiber strain sensors cannot endure a limit strain of 1%. To break through the limit, we propose a hybrid silica/polymer optical fiber sensor. It can endure extraordinarily large strain. The maximum strain of 35% is confirmed by experiments. To achieve high sensitivity and detect a small change in strain, a phase tracking method is used. The sensitivity of the sensor is 28 pm/με which is 28 times larger than that of the traditional FBG sensors. In addition, because of the excellent high-temperature endurance of polyimide (PI) and adhesive, the sensor can survive in the high temperature up to 220 °C. The proposed hybrid silica/polymer optical fiber sensor has potentials to monitor deformation in plastic products, structure health in composite materials, and even strain in biomaterials.
... Using the formulas related to temperature and thermal strain dependencies of Young's modulus of the sensing fiber core E T K = 69.68 + 1.126 x 10 −2 T K and E ε = E 0 ( 1 + 5.75 ε ) respectively [12,13,14], temperature dependence of the thermal strain format ions can be written by ...
Brillouin frequency shift (BFS) and Brillouin power change (BPC) and the core refractive index of the sensing fiber vary linearly with thermal formations in the medium. In this study, a no vel Brillouin Coherent detection based distributed temperature and thermal strain sensing model depending on the core refractive index dependencies of BFS and BPC has been proposed. Using this model, core refractive index dependencies of BFS and BPC ha ve been theoretically analyzed and corresponding simulations have been performed, accordingly. In this research, for 20 °C-39.44 °C temperature range of the sensing fiber, refractive index of the fiber core changes from 1.44183 to 1.44202. Moreover, BFS and BPC values along the sensing fiber have been obtained as 43.80 MH z, 62.05 MHz and 66.92 MHz and 10.44 %, 13.04 % and 13.73 % versus core refractive index values of 1.44193, 1.44200 and 1.44202, respectively. Nevertheless, RMS error values of BFS and BPC have been computed for specific fiber regions along the sensing fiber and then using the interpolation method, linear and quadratic equations of the RMS curves have been derived. According to the results of the simulations and the equations, average values of the frequency and power RMS have been attained as ~ 1.60 MH z and ~ 0.26 %, respectively. Furthermore, quadratic equations related to the core refracti ve index dependencies of Brillouin parameters and the cubic equations relative to the temperature and thermal strain resolutions of the system have been produced by utilizing interpolation and curve fitting methods. Consequently, temperature and thermal strain resolutions of the system have been calculated as ~ 0.76 °C and ~ 46.80 μɛ for the entire length of the sensing fiber, respectively. Keywords: Brillouin Coherent detection, Distributed sensing, Core refractive index of optical fiber, Brillouin frequency shift RM S, Brillouin power change RM S, RM S error value
