CN220743024U - Front end device for monitoring temperature and longitudinal stress of seamless rail - Google Patents
Front end device for monitoring temperature and longitudinal stress of seamless rail Download PDFInfo
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Abstract
The utility model discloses a front-end device for monitoring the temperature and longitudinal stress of a seamless rail, which comprises a monitoring module, a rail clamping module and a control module; the monitoring module comprises two fiber bragg grating strain sensors and a fiber bragg grating temperature sensor; the control module is internally provided with a power supply device, a fiber bragg grating demodulation device and a wireless transmission device and is packaged in the box-type box; the control module is fixed at the bottom of the steel rail through the rail clamping module, the monitoring module is arranged at the rail web of the steel rail through the rail clamping module, and the two fiber bragg grating strain sensors are respectively arranged longitudinally and vertically. The fiber grating demodulation device is used for demodulating output signals of the fiber grating strain sensor and the temperature sensor to obtain corresponding strain signals and temperature signals, and transmitting the corresponding strain signals and temperature signals to the remote terminal equipment through the wireless transmission device for stress calculation. The device applies the fiber bragg grating sensor to the monitoring of the stress change of the steel rail, and is convenient for realizing the real-time monitoring of the risk point of the seamless line.
Description
Technical Field
The present utility model relates to a temperature and strain detecting device.
Background
The high-speed railway generally adopts a seamless line, the seamless line eliminates gaps between steel rails, the impact force of wheel rails is reduced to a great extent, the comfort of the train is improved, and the equipment loss is reduced. However, as the rail gap disappears, the steel rail cannot freely stretch in the longitudinal direction when the temperature changes, so that huge temperature stress is generated in the steel rail, the steel rail becomes one of the reasons for track diseases, problems such as rail expansion and runway are generated when the steel rail is serious, and the operation safety of the high-speed rail is seriously affected. Therefore, at the beginning of the design of a seamless line, the temperature when the longitudinal temperature stress of the steel rail is zero (namely locking the rail temperature) needs to be reasonably selected by taking the history change range of the local temperature into consideration, so that the longitudinal temperature stress of the steel rail is always in a safe range. However, during long-term service of the seamless line, the railway service department performs actual measurement analysis on the existing line, and finds that the actual locking rail temperature often deviates from the designed locking rail temperature.
The reason for the design of the seamless actual lock rail Wen Pianli for the lock rail temperature is mainly as follows:
firstly, in the laying process, initial temperature stress is possibly generated when a steel rail is pulled in and folded in the loading and unloading and transportation processes, so that the actual locking rail temperature is deviated from the original design value;
secondly, in maintenance, the maintenance is generally considered to be safer due to the slightly existing tensile stress in the steel rail under the low-temperature condition, but under the low-temperature condition, the whole section of steel rail contracts, and the steel rail cannot completely return to the original length after locking, so that the temperature of the locked steel rail is reduced;
and thirdly, during operation, the train continuously runs and rolls on the steel rail, so that the steel rail is subjected to plastic elongation deformation, and pressure still exists at the original zero-stress rail temperature, so that the actual locking rail temperature is reduced. In addition, factors such as the insertion of short rails, local tension increase of the steel rail caused by frequent braking before and after a station, and the like can also cause the change of the actual locking rail temperature.
It is important that the line management department grasp the temperature and longitudinal stress of the seamless line rail to prevent the line from expanding the track due to the overrun of the compressive stress of the long rail in the high temperature season and simultaneously prevent the rail from breaking due to the overrun of the tensile stress of the long rail in the low temperature season.
At present, rail temperature in certain areas is manually measured by a rail thermometer in a skylight by a railway line management department, so that the rail temperature stress cannot be obtained in real time, the obtained monitoring data has small density, and the highest rail temperature and the lowest rail temperature in days, months and years are difficult to capture; the method occupies more labor force, has large measurement error and poor real-time performance, so that a timely, accurate and scientific decision basis is difficult to provide for railway work.
The current method for detecting the temperature stress of the steel rail on the seamless line can be divided into a strain method and a stress method in principle. The strain method is to detect the deformation of the steel rail by adopting a certain means so as to obtain the longitudinal stress information of the steel rail, and common strain methods include a displacement observation pile method, a measuring standard method, a deformation method, a strain resistance method and the like.
(1) Displacement observation pile method
Before the long rail is laid, displacement observation piles are buried on shoulders at the center of the long rail and at two sides of the specified position according to the prior design position, namely the starting and ending points of the expansion of the long rail. After the long rail is paved and locked, marks (zero points) are made on the steel rail corresponding to each observation pile immediately and are used as observation points for observing the crawling of the steel rail.
The pile observation method is one of the common methods for monitoring the temperature stress of the steel rail and actually locking the rail temperature by railway service departments due to simple and easily understood principle. The greatest disadvantage of the method is that the observation precision is insufficient, the observation precision is influenced by measuring instruments, observation piles and rail temperature measurement precision, the grasping of displacement is limited to millimeter level, and the method can meet the requirement of daily maintenance and repair, but cannot be widely applied, if the distance between adjacent observation piles is increased when a seamless line is overlong, the monitoring effect can not meet the actual requirement when a steel rail crawls less, in addition, the observation piles are difficult to set at the line positions of bridge transition sections and the like, and the effective monitoring of the temperature stress of the steel rail of the seamless line is greatly discounted.
(2) Measuring method
The standard length of steel rail is marked initially by a common steel ruler in a workshop of a rail welding factory, the length of the standard length of steel rail is generally 24m, and the distance is called as the gauge length, so the method is also called as the gauge length rail length method. Marking is generally carried out using a punch having a diameter of not more than 0.5 mm. The marked steel rails are welded into long steel rails according to the requirements, and a group of marked steel rails are arranged at intervals. After on-site laying, the distance between the gauge points can be measured regularly by using a calibrated steel ruler, and the principle is that the actual locking rail temperature and the change rule thereof are deduced by combining a plurality of groups of measurement data according to the difference value of the gauge distance and the length of the ruler. The accuracy of the current measuring and marking method is about +/-3 ℃ by considering systematic errors and accidental errors existing in the actual measuring process. In addition, the standard measurement method has strict technological process and management system and high technical requirements on measuring staff, so the method is only in a research and test stage and is also time and day apart from wide popularization and use.
(3) Deformation method
The deformation method adopts a deformation measuring instrument consisting of an indium steel ruler and a dial indicator to measure the deformation of the steel rail. The device is generally arranged at a certain fixed position in a neutral layer area of the steel rail, and when the steel rail is deformed, the deformation of the steel rail is obtained through a dial indicator, so that the longitudinal stress in the steel rail is known. The method has the defects that the method is greatly influenced by the installation precision and the reading error, and the practical measurement shows that the precision of the line locking rail temperature detected by adopting a deformation method is about +/-4 ℃ and does not meet the safety requirement, so the method is not widely applied.
(4) Strain resistance method
The methods are relatively visual deformation displacement measurement methods, and domestic and foreign scholars propose a strain resistance method based on the principle. The method adopts a Wheatstone bridge circuit formed by resistance strain gages to measure the longitudinal stress of the steel rail. However, the state monitoring of the track is generally performed outdoors, and is affected by various external factors such as natural environment, and the zero drift and electromagnetic interference of the resistance strain gauge are serious.
The stress method is characterized in that the longitudinal stress in the steel rail can be directly obtained, and the representative methods include a vertical tension method, a Barkhausen method, an X-ray method, an ultrasonic method and the like.
(1) Vertical pulling method
The force of the magnitude F acts on the two ends of the steel rail to release the fastener within the length range L and the distance between the two ends L of the steel rail 1 、L 4 Respectively placing the height H 1 And H is 2 Then a pulling force P is applied at the midpoint of the rail, and the resulting displacement is noted as H. When the length of L reaches a certain value, the steel rail can be regarded as a chord with fixed two ends and a tensile force F. If F is unchanged and Δh is within a certain range, the ratio of the pulling force P to the displacement H remains unchanged, i.e. the lifting stiffness k=p/Δh of the string is constant. And calculating the relation between the lifting rigidity K and the tension F by adopting a finite element method, so as to obtain the longitudinal stress. The method is simple in principle, but the method needs to be carried out in skylight time, a fastener with a certain length needs to be released, time and labor are wasted, and meanwhile, longitudinal stress can be generated in the steel rail when the steel rail is lifted, and the detection result is influenced, so that the method is not suitable for long-term monitoring of the temperature stress of the steel rail.
(2) Barkhausen method
Barkhausen (BARBHAUSEN) noise was taught by the university of Dresden, germany in 1919, and its study found that ferromagnetic materials were composed of small magnetic domains of different orientations, and that the total magnetization effect of the ferromagnetic materials tended to zero without disturbance from the external environment. When the tensile stress in the steel rail is larger, the Barkhausen signal is enhanced, otherwise, if the compressive stress exists in the steel rail, the Barkhausen signal is reduced along with the increase of the compressive stress.
The Barkhausen method is based on the principle, and although the method is simple and quick, the detection result is greatly influenced by the internal structure of the steel rail, which is one of the reasons why the method cannot be widely applied.
(3) X-ray method
According to the theory of elastic mechanics and X-ray crystallography, under the stress-free condition, the distances d between the same-family crystal faces in different directions of an ideal polycrystal are equal, if residual stress exists, the distances between the same-family crystal faces of different crystal grains can be regularly changed along with the directions of the crystal faces and the sizes of the stress, so that the X-ray diffraction lines are caused to deviate, and the basic principle of detecting the stress by an X-ray method is adopted.
Under the action of tensile stress, the interplanar spacing of the detected structure becomes larger, the diffraction angle becomes smaller, and under the action of compressive stress, the interplanar spacing becomes smaller and the diffraction angle is increased. Therefore, the stress value can be obtained by measuring the change speed of the diffraction angle. However, the method has a small detection range, and can only detect the stress condition of the surface of the steel rail within a range of tens of micrometers, so that the result is greatly influenced by the residual stress of the surface of the steel rail, and the method is not suitable for wide application.
In the above detection and monitoring methods, the strain method needs to be calibrated in the zero stress state of the seamless rail, and the partial stress method needs to be calibrated on the rail material, thus causing certain limitation to the application of the field detection and monitoring technology; the method for directly calculating the longitudinal force of the steel rail and the actual locking rail temperature according to the rigidity and physical stress model does not need to calibrate the steel rail material or calibrate the steel rail in a zero stress state of the seamless rail, is a detection method convenient and quick to operate, and does not meet the requirement for real-time monitoring of the longitudinal stress of the steel rail of the seamless rail.
While fiber optic sensing technology is now the leading edge and popular technology in the sensing arts, it has now been applied to various fields including civil engineering. The sensing process based on the fiber bragg grating is to obtain sensing information by directly influencing the wavelength drift of the fiber bragg grating through strain, and is a wavelength modulation type fiber bragg sensor. The fiber bragg grating has the advantages of capability of measuring strain and temperature simultaneously, high structural integration level, accurate measurement result, cost saving and the like. Therefore, the fiber bragg grating sensing technology is utilized to monitor the temperature and stress state of the steel rail, and a new direction is opened up for the state monitoring of the seamless rail.
In the fiber grating sensor, light with a certain bandwidth is incident into the fiber grating through a circulator by a wide-spectrum light source (such as SLED or ASE), the light meeting the condition is reflected back under the wavelength selectivity action of the fiber grating, and then the light is sent into a demodulation device through the circulator to measure the reflection wavelength change of the fiber grating. When the fiber grating is used as a probe to measure the external temperature or strain, the change of the reflection wavelength is caused by the change of the grating pitch of the grating, and the demodulation device deduces the external temperature or strain by detecting the change of the wavelength.
Disclosure of Invention
The utility model aims to: aiming at the prior art, a front-end device for monitoring the temperature and the longitudinal stress of a seamless rail is provided, and the front-end device is used for outputting the temperature and the strain signals of the rail to remote terminal equipment in real time to calculate the longitudinal stress.
The technical scheme is as follows: a front-end device for monitoring the temperature and longitudinal stress of a seamless rail comprises a monitoring module, a rail clamping module and a control module; the monitoring module comprises two fiber bragg grating strain sensors and a fiber bragg grating temperature sensor; the control module is internally provided with a power supply device, a fiber bragg grating demodulation device and a wireless transmission device, and is packaged in a box; the control module is fixed at the bottom of the steel rail through the rail clamping module, the monitoring module is arranged at the rail web of the steel rail through the rail clamping module, and the two fiber bragg grating strain sensors are respectively arranged longitudinally and vertically; the fiber bragg grating demodulation device is used for demodulating output signals of the two fiber bragg grating strain sensors and the fiber bragg grating temperature sensor to obtain corresponding strain signals and temperature signals, and the strain signals and the temperature signals are sent to remote terminal equipment through the wireless transmission device to perform stress calculation.
Further, ear plates are vertically arranged in the middle of the front side and the rear side of the box-shaped box respectively; the rail clamping module comprises two bolts which respectively and correspondingly penetrate through the lug plate horizontally; each bolt is respectively sleeved with a pair of clamping plates for clamping two sides of the rail bottom of the steel rail, a spring is arranged between the two clamping plates and the lug plate, and the other end of the bolt is provided with a fastening nut; vertical baffles are fixed at the tops of the front clamping plate and the rear clamping plate which are positioned on the same side; the monitoring module is arranged in the protective cover, and the protective cover is fixedly connected to the vertical baffle.
Further, the fiber bragg grating strain sensor is packaged by adopting a sheet type surface adhesion, and comprises a mechanical fixing sheet, wherein the mechanical fixing sheet comprises an elastic beam, a base connected with two ends of the elastic beam, a grating grid area is arranged on the surface of the elastic beam, and the base is fixed on the protective cover through screws.
Furthermore, the fiber grating temperature sensor adopts tubular package and comprises a grating region positioned on a metal substrate, wherein two ends of the grating region are connected with polyimide tubes, and the whole outside is a metal shell.
Furthermore, two ends of the protective cover facing the outer side face of the rail web of the steel rail are respectively provided with a magnetic attraction device.
The beneficial effects are that: the utility model applies the fiber bragg grating sensor to the monitoring of the stress change of the steel rail, realizes the real-time monitoring of the risk point of the seamless line, takes the fiber bragg grating as a sensing medium, has the characteristics of high sensitivity, corrosion resistance, electromagnetic interference resistance and the like, and can be suitable for the strain measurement in the severe environment.
The control module of the device is arranged at the bottom of the steel rail, fully utilizes the space at the bottom of the rail, avoids the operation of drilling or welding on the rail to damage the rail, and does not influence the rail structure. Meanwhile, in order to reduce the damage of vibration to equipment when a train passes, a damping spring is arranged between the control module and the rail clamping module, so that the control module can be effectively protected from being damaged. Meanwhile, the control module adopts a waterproof structure design to prevent rainwater from entering the control box to damage equipment.
Drawings
FIG. 1 is a view of a state of use reference of the device of the present utility model;
FIG. 2 is a schematic diagram of the structure of the device of the present utility model;
FIG. 3 is a schematic view of the external structure of a control module in the device of the present utility model;
FIG. 4 is a schematic diagram of the internal structure of a control module in the apparatus of the present utility model;
FIG. 5 is a schematic view of a mechanical stator of a fiber bragg grating strain sensor in the apparatus of the present utility model;
FIG. 6 is a schematic diagram of a package structure of a fiber grating temperature sensor in the device of the present utility model;
fig. 7 is a schematic view of the appearance structure of a fiber grating temperature sensor in the device of the present utility model.
Detailed Description
The utility model is further explained below with reference to the drawings.
As shown in fig. 1 to 4, a front end device for monitoring the temperature and longitudinal stress of a seamless rail comprises a monitoring module 1, a rail clamping module 2 and a control module 3. The monitoring module 1 comprises two fiber bragg grating strain sensors and one fiber bragg grating temperature sensor. The control module 3 is internally provided with a power supply device, a fiber bragg grating demodulation device and a wireless transmission device, and the control module 3 is packaged in the box 301. The control module 3 is fixed in rail 4 bottom through clamp rail module 2, and monitoring module 1 arranges in rail web department through clamp rail module 2, and two fiber bragg grating strain sensor are vertical and vertical setting respectively. The fiber bragg grating demodulation device is used for demodulating output signals of the two fiber bragg grating strain sensors and the fiber bragg grating temperature sensor to obtain transverse and vertical strain signals of the steel rail and steel rail temperature signals, and the signals are sent to the remote terminal equipment through the wireless transmission device to perform stress calculation.
Specifically, the middle parts of the front and rear sides of the box 301 are vertically provided with ear plates 302, respectively. The rail clamping module 2 comprises two bolts 201 which respectively and correspondingly penetrate through the lug plates 302 horizontally, a pair of clamping plates 202 used for clamping two sides of the rail bottom of the steel rail are respectively sleeved on each bolt 201, a spring 203 is arranged between each clamping plate 202 and each lug plate 302, and a fastening nut 204 is arranged at the other end of each bolt 201. A vertical baffle 205 is fixed to the top of the front and rear clamping plates 202 on the same side. In order to prevent the monitoring module 1 from being affected by external environment during use, the monitoring module 1 is placed in the protective cover 101, and the protective cover 101 is fixedly connected to the vertical baffle 205 by using 4M 5 bolts. The two ends of the protective cover 101 facing the outer side surface of the rail web of the steel rail are respectively provided with a magnetic attraction device 102.
As shown in fig. 5, the fiber grating strain sensor adopts a sheet type surface adhesive package, and comprises a mechanical fixing sheet, wherein the mechanical fixing sheet comprises an elastic beam, bases connected with two ends of the elastic beam, grating regions are arranged on the surface of the elastic beam, and the bases are fixed on a protective cover 101 through screws. Mechanical property analysis is performed on the mechanical fixing piece by ANSYS software under various working conditions to obtain a stress cloud picture and a deformation cloud picture, and the structural stress of the packaging substrate structure is found to be dispersed through simulation, the stress of the middle part is larger, the middle part is free from bulge deformation, the structural reliability is higher, and the environment change can be accurately and sensitively caused. Through finite element simulation, the package substrate is verified to be beneficial to monitoring the stress strain of the fiber bragg grating.
When an optical fiber is used as a temperature sensing element, the temperature sensing element is usually required to be packaged, and the optical fiber is fragile in material and is extremely easy to break under the action of external force. As shown in fig. 6 and 7, the fiber grating temperature sensor adopts a tube package, and comprises a grating region 1052 on a metal substrate 1051, wherein two ends of the grating region are connected with polyimide tubes 1053, and the whole outside is a metal shell 1054. The middle of the metal shell 1054 is a cylinder, two ends of the metal shell are tapered gradually, and the position of the grating region 1052 is near the central axis of the cylinder. According to analysis of a temperature sensing model, the sensitivity of the fiber bragg grating to temperature is micro-deformation according to thermal expansion and cold contraction of a measured piece, so that the period and the effective refractive index of the fiber bragg grating are changed, and finally the center wavelength of the fiber bragg grating is shifted, so that constraint and boundary conditions are fixed constraint and tensile stress when ANSYS finite element simulation analysis is carried out on the fiber bragg grating temperature sensor. From the strain distribution diagram, the deformation of the fiber grating temperature sensor packaging structure under tensile stress is as follows: the strain is gradually decreased from the bottom to the top in a step shape, and the whole stress of the package is uniformly distributed. The position of the fiber grating is near the central axis of the cylinder, and the ANSYS analysis cloud chart shows that the perceived strain is half of the maximum strain of the bottom layer, so that the fiber grating is guaranteed to have good sensing performance on temperature after packaging, and the packaging has a certain desensitizing effect from a certain angle, so that the influence of stress change on the packaged fiber grating temperature sensor is reduced, and the accuracy of temperature measurement in practical engineering use is improved.
The device adopts lithium battery power supply, and the power supply device is positioned inside the control module, and the control module is integrally designed by adopting a waterproof structure, so that rainwater is prevented from entering the control box to damage equipment. The rail clamping module 2 is used for fixing the monitoring module 1 and the control module 3, fixing the monitoring module 1 at the rail web of the outer side of the steel rail, and fixing the control module 3 at the rail bottom of the steel rail. The control module 3 is of a box structure, and is used for receiving the central wavelength data transmitted by the monitoring module 1, converting the wavelength data into temperature and strain data by utilizing the fiber bragg grating demodulation device, and finally transmitting the temperature and strain data to the remote terminal equipment through the wireless transmission device. The modulation principle and the specific implementation process of the fiber grating demodulation device are all the prior art.
And the remote terminal equipment calculates the longitudinal stress of the steel rail according to the received temperature and strain signals, so that the real-time monitoring of the risk point of the seamless line is realized, namely, scientific guidance is provided for maintenance and repair of the seamless line through the collected steel rail stress and temperature data.
When the environment where the fiber grating sensor is located changes, the period of the fiber grating and the effective refractive index of the grating mode change. When the period of the grating and the effective refractive index of the grating mode are changed, the central reflection wavelength of the fiber grating is changed, and if the change of the external physical quantity is required to be obtained, the change can be obtained by measuring the drift quantity of the resonance wavelength. The external strain and temperature variations are the main causes of the shift in the center wavelength of the fiber bragg grating. The temperature influence is not considered, and under the action of axial strain, the central reflection wavelength of the fiber Bragg grating is in a linear relation with the axial strain; the center reflection wavelength of the fiber Bragg grating is in a linear relation with the temperature change under the action of temperature without considering the stress influence. Because the change of the center wavelength of the fiber Bragg grating is related to the strain and the temperature, if the change of the strain is required to be obtained independently, if the change of the ambient temperature cannot be compensated effectively, the measurement of the fiber Bragg grating sensor is affected, and therefore, the temperature is required to be compensated for when the strain is required to be obtained independently.
Under the action of no additional force, the steel rail is restrained in the longitudinal direction due to the locking action of the steel rail fastener, and the longitudinal deformation of the steel rail is limited, so that the longitudinal temperature of the steel rail becomes zero. Although the longitudinal direction is not subjected to temperature strain, the vertical direction of the steel rail is in a free state, and the vertical direction of the steel rail is strained under the action of temperature stress. The temperature stress can be obtained by measuring the vertical strain. The fiber grating sensing principle can show that the center wavelength of the fiber grating changes under the action of temperature or strain. The device arranges three fiber grating sensors at the rail web, namely, one fiber grating strain sensor 103 and one fiber grating strain sensor 104 are respectively arranged at the rail web of the steel rail in the longitudinal direction and the vertical direction, the temperature sensitivity and the strain sensitivity of the two sensors are the same, and a fiber grating temperature sensor 105 is additionally arranged. The longitudinal fiber bragg grating strain sensor 103 can monitor strain generated by additional forces such as braking force of a train and expansion and contraction of a bridge, so that the change amount of the actual locking rail temperature of the steel rail can be calculated conveniently by remote terminal equipment; the vertical fiber bragg grating strain sensor 104 can obtain the rail strain in the vertical direction when the rail temperature changes. The remote terminal device can also perform temperature compensation according to the temperature measured by the fiber grating temperature sensor 105, so as to eliminate the influence of the temperature on the fiber grating strain sensor.
The principle of the remote terminal device for calculating stress according to the output signal of the device is briefly described as follows.
The fiber bragg grating strain sensor 103 can monitor the strain generated by the braking force of the train, the expansion and contraction of the bridge and other additional forces, and further calculate the change amount of the actual locking rail temperature of the steel rail, and the principle is as follows:
wherein Deltalambda 1 Is 103 central wavelength variation, lambda 1 Is 103 central wavelength, K ε Is the strain sensitivity coefficient, ε is the strain change, K T Is the temperature sensitivity coefficient, delta T is the change of the rail temperature relative to the locking rail temperature, epsilon f The strain generated by the braking force of the train, the expansion and contraction of the bridge and other additional forces, namely the equal strain generated by the elongation of the optical fiber by the steel rail through the force, is respectively the thermal expansion coefficient of the optical fiber grating and the thermal-optical coefficient of the optical fiber grating.
Due to the locking effect of the rail fastener, the rail is restrained in the longitudinal direction and not restrained in the vertical direction, and the fiber bragg grating strain sensor 104 can obtain the rail strain in the vertical direction when the temperature of the rail changes.
The strain generated by the poisson effect is caused by the elongation or shortening of the steel rail and the application of force to the sensor f +μβΔt); the vertical direction of the steel rail is in a free state, but the linear expansion coefficient beta of the steel rail is larger than the linear expansion coefficient alpha of the fiber bragg grating, so that the strain corresponding to alpha delta T is free strain, and (beta-alpha) delta T is constraint strain, namely the strain generated by the steel rail strain driving sensor through force, and the principle is shown as follows:
wherein Deltalambda 2 Is 104 central wavelength variation, lambda 2 Is 104 center wavelength, μ is poisson's ratio of the rail, β is linear expansion coefficient. Then there are:
wherein F is z Is the longitudinal force of a seamless rail, F t Is the basic temperature force of the steel rail, F s Is a telescopic beam for bridge temperature changeThe additional force of expansion and contraction caused by rail interaction, E is the modulus of elasticity of the rail and F is the cross-sectional area of the rail.
The method is the basic principle of a steel rail temperature force bidirectional strain test scheme based on fiber gratings. It can be seen that rail temperature force and relative wavelength difference are linear.
The remote terminal equipment is arranged in a rear working section or workshop, can download collected data from a network cloud and analyze and process the data, and finally stores all the data in a server for a long time. The data acquisition of the remote monitoring terminal system is mainly automatic acquisition and is manually assisted.
In the embodiment, the device performs multiple data measurements within 24 hours after installation, and effectively monitors and analyzes the change condition of the rail temperature force at different times of day and under different temperature conditions through the remote terminal equipment, wherein the data sampling time interval in the test is fixed to be 2 seconds. Since this test time is approximately one whole day, the temperature profile generally reflects the change of rail, roadbed, atmosphere for one whole day, gradually increasing in temperature over time from the morning to a maximum in temperature between 2 pm, and then gradually decreasing again. The temperature profile also reflects that the rail temperature change is greater than atmospheric temperature change at near high temperatures, but at low temperatures the rail temperature is substantially consistent with the bridge temperature change. The roadbed is made of large-volume concrete and has the worst sensitivity to heat, so that the change amplitude and the change trend are smaller. In the change trend, the change of the steel rail and the atmospheric temperature is synchronous, and the change of the temperature of the roadbed is lagged. The subgrade has the smallest temperature change amplitude at high temperature, but has higher temperature than the atmosphere and the steel rail at low temperature.
The foregoing is merely a preferred embodiment of the present utility model and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present utility model, which are intended to be comprehended within the scope of the present utility model.
Claims (5)
1. The front-end device for monitoring the temperature and longitudinal stress of the seamless rail is characterized by comprising a monitoring module (1), a rail clamping module (2) and a control module (3); the monitoring module (1) comprises two fiber bragg grating strain sensors and a fiber bragg grating temperature sensor; a power supply device, a fiber bragg grating demodulation device and a wireless transmission device are arranged in the control module (3), and the control module (3) is packaged in a box-type box (301); the control module (3) is fixed at the bottom of a steel rail through the rail clamping module (2), the monitoring module (1) is arranged at the rail web of the steel rail through the rail clamping module (2), and the two fiber bragg grating strain sensors are respectively arranged longitudinally and vertically; the fiber bragg grating demodulation device is used for demodulating output signals of the two fiber bragg grating strain sensors and the fiber bragg grating temperature sensor to obtain corresponding strain signals and temperature signals, and the strain signals and the temperature signals are sent to remote terminal equipment through the wireless transmission device to perform stress calculation.
2. Front end device for monitoring the temperature and longitudinal stress of a seamless rail according to claim 1, characterized in that the middle parts of the front and rear sides of the box (301) are respectively vertically provided with an ear plate (302); the clamping rail module (2) comprises two bolts (201) which respectively and horizontally penetrate through the lug plate (302); a pair of clamping plates (202) for clamping two sides of the rail bottom of the steel rail are sleeved on each bolt (201), a spring (203) is arranged between each clamping plate (202) and each lug plate (302), and a fastening nut (204) is arranged at the other end of each bolt (201); the tops of the front clamping plate (202) and the rear clamping plate (205) which are positioned on the same side are fixedly provided with vertical baffles (205); the monitoring module (1) is arranged in the protective cover (101), and the protective cover (101) is fixedly connected to the vertical baffle (205).
3. The front-end device for monitoring the temperature and longitudinal stress of a seamless rail according to claim 2, wherein the fiber bragg grating strain sensor is packaged by adopting a sheet type surface adhesion, and comprises a mechanical fixing sheet, wherein the mechanical fixing sheet comprises an elastic beam, bases connected with two ends of the elastic beam, grating regions are arranged on the surface of the elastic beam, and the bases are fixed on the protective cover (101) through screws.
4. The front-end device for monitoring the temperature and longitudinal stress of a seamless rail according to claim 2, wherein the fiber bragg grating temperature sensor is packaged in a tube type, and comprises a grating region positioned on a metal substrate, wherein two ends of the grating region are connected with polyimide tubes, and the whole outside is a metal shell.
5. Front end device for monitoring the temperature and longitudinal stress of a seamless rail according to any of the claims 2-4, characterized in that the two ends of the protective cover (101) facing the outer side of the web of the rail are provided with a magnetic attraction device (102), respectively.
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| CN202322360391.5U CN220743024U (en) | 2023-08-31 | 2023-08-31 | Front end device for monitoring temperature and longitudinal stress of seamless rail |
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| CN202322360391.5U CN220743024U (en) | 2023-08-31 | 2023-08-31 | Front end device for monitoring temperature and longitudinal stress of seamless rail |
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