阅读说明：本技术 一种轨道扣件损伤的监测方法 (Method for monitoring damage of rail fastener ) 是由 蒋吉清 苏鑫杰 章亦然 蔡泽甬 吴熙 孙苗苗 于 2020-12-31 设计创作，主要内容包括：本发明涉及一种轨道扣件损伤的监测方法,包括步骤：步骤1、钢轨位移响应计算；步骤2、摩擦纳米发电机输出信号计算；步骤3、摩擦纳米发电机实测。本发明的有益效果是：在实际运营轨道安装摩擦纳米发电机,将监测所得电信号与计算所得的输出电压时程曲线进行对比,推算扣件损伤情况,并结合多个摩擦纳米发电机进行分析。直接对比模拟计算电压和实测电压,使用简单便捷。该方法可以监测轨道扣件损伤情况,保障列车系统运营安全。并且利用摩擦纳米发电机作为自供能传感器,减少人工检修耗费的人力物力。(The invention relates to a method for monitoring damage of a track fastener, which comprises the following steps: step 1, calculating the displacement response of the steel rail; step 2, calculating an output signal of the friction nano generator; and 3, actually measuring the friction nano generator. The invention has the beneficial effects that: installing the friction nano generator on an actual operation track, comparing the monitored electric signal with the calculated output voltage time-course curve, calculating the damage condition of the fastener, and analyzing by combining a plurality of friction nano generators. The direct comparison analog computation voltage and the actual measurement voltage are simple and convenient to use. The method can monitor the damage condition of the rail fastener and guarantee the operation safety of the train system. And utilize the friction nanometer generator as self-power supply sensor, reduce the manpower and materials that artifical maintenance consumed.)

1. A method for monitoring damage of a rail fastener is characterized by comprising the following steps:

firstly, obtaining an output signal rule of the friction nano generator under the steel rail under different fastener damage conditions through vehicle rail coupling theoretical calculation and friction nano generator theoretical calculation;

then, install in actual operation track friction nanometer generator uses the patrol and examine car to patrol and examine at non-operation period, and every friction nanometer generator output signal of telecommunication of record is found corresponding fastener damage situation in the output signal law picture under the different fastener damage circumstances.

2. The method for monitoring damage to a rail fastener according to claim 1, comprising the steps of:

step 1, steel rail displacement response calculation:

establishing a train-steel rail-track bed coupling calculation finite element model, wherein the vertical and nodding displacement is considered for a train body and a bogie, the vertical displacement is only considered for a wheel set, and the bogie and the wheel set, and the carriage and the bogie are respectively connected by primary suspension and secondary suspension; the steel rail adopts a flexible solid model, fasteners below the steel rail are distributed in a scattered mode at equal intervals, and a spring-damping unit is adopted for simulation; the ballast bed and the lining adopt rigid models; the steel rail is in an ideal state;

selecting a plurality of fastener damage working conditions, wherein the fastener damage working conditions comprise the number and the positions of the damaged fasteners, and the rigidity value of the fasteners and the steel rail in the fastener damage process is 0; calculating through a train-steel rail-track bed coupling calculation finite element model to obtain a middle point position between two fasteners, namely a steel rail displacement time curve z (t) of the installation position of the friction nano generator;

step 2, calculating an output signal of the friction nano generator:

the output signal of the friction nanogenerator is calculated according to the following formula

Wherein d is₀＝d₁/ε_r1+d₂/ε_r2Is an effective thickness constant, d₁、d₂Thickness, ε, of Nylon and PTFE, respectively_r1、ε_r2Dielectric constants of nylon and PTFE, respectively; epsilon₀Sigma is the charge density of the surface of the dielectric material, R is the size of the external resistor, S is the area of the friction pair, D (t) is the clearance of the friction pair, and the dielectric constant in vacuum is calculated according to the following formula

Wherein z (t) is the rail displacement of the monitoring position, A is the initial gap of the friction pair, and the value of the initial gap of the friction pair is calculated according to the calculation result, and is larger than the rail displacement when no fastener is damaged and smaller than the rail displacement when a plurality of fasteners are damaged;

by adopting a numerical integration mode, the relationship between the output signal of the friction nano generator at the monitoring position and the damage number and position of the fastener can be obtained, a table corresponding to the damage condition of the fastener and the damage signal of the friction nano generator is manufactured, whether the output signal of the friction nano generator is close to that under different damage working conditions in the table is checked, if yes, the initial clearance of the friction pair is changed, each working condition is recalculated according to the initial clearance, and the table is manufactured;

step 3, actually measuring the friction nano generator:

installing a plurality of friction nanometer generators between the steel rail and the track bed and at the middle positions of the two fasteners, wherein the initial gap is finally adopted according to the step 2; regularly using a test vehicle to carry out constant-speed inspection in a non-operation period, wherein the vehicle body parameters and the driving parameters of the test vehicle are the same as those of the finite element model established in the step 1;

extracting an output electric signal of the friction nano generator under the steel rail through which the test vehicle passes, recording the output electric signal, finding out the damage working condition of the corresponding fastener, and obtaining the damage condition of the fastener measured by a single monitoring device; the joint is compared a plurality of friction nanometer generator monitoring operating mode, and the number and the position of fastener damage are finally confirmed.

3. The method of monitoring rail fastener damage according to claim 1, wherein: the friction nano generator is based on a contact-separation type friction nano generator, consists of a friction pair, an electrode layer, a supporting layer and a buffer layer, is placed between a steel rail and a track bed, and is positioned in the middle of every two fasteners. The working principle is as follows: when the train passes through the rail, the rail vibrates in a reciprocating manner, when the rail displaces vertically downwards, the rail drives the upper half part of the friction pair to move downwards, the inner surfaces of the friction pair are continuously close until contacting and generating friction and charge transfer, and the buffer layer is extruded at the moment to protect the friction nano generator from being damaged under the action of train load; then the steel rail is vertically restored, the friction pairs are separated, at the moment, the gap between the friction pairs is changed, the electric potential between the electrode layers on the two sides is changed, and therefore electric potential difference is generated, and therefore current is generated in an external circuit connected with the lead. When the steel rail fastener is damaged or even fails, the vibration response of the steel rail is changed, so that the output signal of the friction nano generator is changed, and the number and the position of the damage of the fastener are presumed according to the electric signal.

4. The method of claim 3, wherein the step of monitoring damage to the rail clip comprises: the friction pair of the friction nano generator consists of a top dielectric material layer and a bottom dielectric material layer, the top dielectric material layer and the bottom dielectric material layer have the same area and opposite polarity, are completely paved in a film form and are parallel and opposite, and a certain initial gap is reserved between the top dielectric film layer and the bottom dielectric film layer; the electrode layers are two copper foils, are respectively bonded to the top dielectric material layer and the bottom dielectric material layer and are positioned at the outer sides of the friction pairs, and the copper foils are connected with leads which can output current; the supporting layer is composed of two acrylic flat plates which are respectively bonded to the outer sides of two copper foils of the electrode layer, so that the friction pair and the electrode layer are kept in a plane; the buffer layer is made of sponge or rubber materials and is positioned below the supporting layer below the buffer layer and used for buffering train load and protecting the structural safety of the friction nano generator.

Technical Field

The invention relates to the technical field of underground engineering, in particular to a method for monitoring damage of a track fastener.

Background

After the subway rail is operated for a long time, the fastener is used as an element for connecting the steel rail and the rail plate, and the conditions of breakage, falling and the like of the fastener elastic strip are easily generated in the continuous operation process of the subway, so that the dynamic response of a subway rail system is aggravated, and even the normal operation of a train is influenced. Therefore, the method for detecting the damage of the fastener has important guiding significance and application value for maintaining the safety of the subway rail and protecting the surrounding environment.

After the steel rail fastener is damaged, the supporting rigidity of the steel rail fastener is reduced sharply, so that the vibration response of the steel rail is changed greatly when a train passes through the steel rail fastener, and the steel rail fastener is related to the damaged position and the number of the fasteners. The current detection methods for damaged fasteners mainly include: frequency domain signal processing, image processing, manual polling, and the like. There is no method for monitoring the location of fastener damage by altering the vibrational response of a local rail by fastener damage.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for monitoring damage of a rail fastener.

The method for monitoring the damage of the rail fastener comprises the following steps: firstly, obtaining an output signal rule of the friction nano generator under the steel rail under different fastener damage conditions through vehicle rail coupling theoretical calculation and friction nano generator theoretical calculation; secondly, install in actual operation track friction nanometer generator uses the patrol and examine car to patrol and examine at non-operation period, and every friction nanometer generator output signal of telecommunication of record is found corresponding fastener damage situation in the output signal law picture under the different fastener damage circumstances.

Preferably, the method specifically comprises the following steps:

step 1, steel rail displacement response calculation:

establishing a train-steel rail-track bed coupling calculation finite element model, wherein a train body adopts a 10-freedom-degree multi-rigid-body train model, namely the train body and a bogie consider vertical and nodding displacement, a wheel set only considers vertical displacement, and the bogie and the wheel set, and a carriage and the bogie are respectively connected by primary suspension and secondary suspension; the steel rail adopts a flexible solid model, fasteners below the steel rail are distributed in a scattered mode at equal intervals, and a spring-damping unit is adopted for simulation; the ballast bed and the lining adopt rigid models; the steel rail is in an ideal state, and the irregularity of the rail is not considered;

selecting a plurality of fastener damage working conditions, wherein the fastener damage working conditions comprise the number and the positions of the damaged fasteners, and the rigidity value of the fasteners and the steel rail in the fastener damage process is 0; calculating through a train-steel rail-track bed coupling calculation finite element model to obtain a middle point position between two fasteners, namely a steel rail displacement time curve z (t) of the installation position of the friction nano generator;

step 2, calculating an output signal of the friction nano generator:

the output signal of the friction nanogenerator is calculated according to the following formula

Wherein d is₀＝d₁/ε_r1+d₂/ε_r2Is an effective thickness constant, d₁(d₂) And ε_r1(ε_r2) The thickness and dielectric constant of nylon and PTFE, respectively; epsilon₀Sigma is the charge density of the surface of the dielectric material, R is the size of the external resistor, S is the area of the friction pair, D (t) is the clearance of the friction pair, and the dielectric constant in vacuum is calculated according to the following formula

Wherein z (t) is the rail displacement of the monitoring position, A is the initial gap of the friction pair, and the value of the initial gap of the friction pair is calculated according to the calculation result, and is larger than the rail displacement when no fastener is damaged and smaller than the rail displacement when a plurality of fasteners are damaged;

by adopting a numerical integration mode, the relationship between the output signal of the friction nano generator at the monitoring position and the damage number and position of the fastener can be obtained, a table corresponding to the damage condition of the fastener and the damage signal of the friction nano generator is manufactured, whether the output signal of the friction nano generator is close to that under different damage working conditions in the table is checked, if yes, the initial clearance of the friction pair is changed, each working condition is recalculated according to the initial clearance, and the table is manufactured;

step 3, actually measuring the friction nano generator:

installing a plurality of friction nanometer generators between the steel rail and the track bed and at the middle positions of the two fasteners, wherein the initial gap is finally adopted according to the step 2; regularly using a test vehicle to carry out constant-speed inspection in a non-operation period, wherein the vehicle body parameters and the driving parameters of the test vehicle are the same as those of the finite element model established in the step 1;

extracting an output electric signal of the friction nano generator under the steel rail through which the test vehicle passes, recording the output electric signal, finding out the damage working condition of the corresponding fastener, and obtaining the damage condition of the fastener measured by a single monitoring device; the joint is compared a plurality of friction nanometer generator monitoring operating mode, and the number and the position of fastener damage are finally confirmed.

Preferably, the method comprises the following steps: the friction nano generator is based on a contact-separation type friction nano generator, consists of a friction pair, an electrode layer, a supporting layer and a buffer layer, is placed between a steel rail and a track bed, and is positioned in the middle of every two fasteners. The working principle is as follows: when the train passes through the rail, the rail vibrates in a reciprocating manner, when the rail displaces vertically downwards, the rail drives the upper half part of the friction pair to move downwards, the inner surfaces of the friction pair are continuously close until contacting and generating friction and charge transfer, and the buffer layer is extruded at the moment to protect the friction nano generator from being damaged under the action of train load; then the steel rail is vertically restored, the friction pairs are separated, at the moment, the gap between the friction pairs is changed, the electric potential between the electrode layers on the two sides is changed, and therefore electric potential difference is generated, and therefore current is generated in an external circuit connected with the lead. When the steel rail fastener is damaged or even fails, the vibration response of the steel rail is changed, so that the output signal of the friction nano generator is changed, and the number and the position of the damage of the fastener are presumed according to the electric signal.

Preferably, the method comprises the following steps: the friction pair of the friction nano generator consists of a top dielectric material layer and a bottom dielectric material layer, the top dielectric material layer and the bottom dielectric material layer have the same area and opposite polarity, are completely paved in a film form and are parallel and opposite, and a certain initial gap is reserved between the top dielectric film layer and the bottom dielectric film layer; the electrode layers are two copper foils, are respectively bonded to the top dielectric material layer and the bottom dielectric material layer and are positioned at the outer sides of the friction pairs, and the copper foils are connected with leads which can output current; the supporting layer is composed of two acrylic flat plates which are respectively bonded to the outer sides of two copper foils of the electrode layer, so that the friction pair and the electrode layer are kept in a plane; the buffer layer is made of sponge or rubber materials and is positioned below the supporting layer below the buffer layer and used for buffering train load and protecting the structural safety of the friction nano generator.

The method has the advantages that finite element software is adopted to calculate the steel rail displacement response time-course curves under different fastener damage working conditions, the curves are substituted into a friction nano-generator output calculation formula, and the output electric signal of the friction nano-generator under each working condition is obtained through calculation. Installing the friction nano generator on an actual operation track, comparing the monitored electric signal with the calculated output voltage time-course curve, calculating the damage condition of the fastener, and analyzing by combining a plurality of friction nano generators. The direct comparison analog computation voltage and the actual measurement voltage are simple and convenient to use. The method can monitor the damage condition of the rail fastener and guarantee the operation safety of the train system. And utilize the friction nanometer generator as self-power supply sensor, reduce the manpower and materials that artifical maintenance consumed.

Drawings

FIG. 1 is a side view of the installation position of a friction nano-generator in a rail

FIG. 2 is a top view of the installation position of the friction nano-generator in the rail

FIG. 3 is a schematic structural diagram of a friction nano-generator

FIG. 4 shows the calculation results of the output signals of the friction nano-generator under the damage conditions of 4 fasteners

FIG. 5 is an example of monitoring results

Description of reference numerals: 1-a steel rail; 2-rail fastener I; 3-steel rail fastener II; 4-a sleeper; 5-friction nano-generator; 6-ballast bed; 7-upper support layer; 8-upper electrode layer; 9-upper half of the friction pair (top dielectric material layer); 10-lower half of the friction pair (bottom dielectric material layer); 11-a lower electrode layer; 12-a lower support layer; 13-a buffer layer; 14-conducting wire.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

As an example:

as shown in fig. 1-2, the friction nano-generator 5 of the present invention is installed between a steel rail 1 and a track bed 6, and is installed at a position between two fasteners of the steel rail, and the adjacent fasteners can be divided into a 2-rail fastener I and a 3-rail fastener II, which are close to each other, according to the positional relationship with the friction nano-generator.

As shown in fig. 3, the friction nanogenerator is composed of a friction pair, an electrode layer, a support layer and a buffer layer, wherein the friction pair is composed of a friction pair upper half part 9 made of a commercial nylon film and a friction pair lower half part 10 made of a polytetrafluoroethylene film, the friction pair upper half part 9 and the friction pair lower half part 10 are the same in size, are completely paved and are opposite in parallel, and an initial gap is reserved between the friction pair upper half part and the friction pair lower half part. An upper electrode layer 8 made of copper foil is bonded on the upper side of the upper half part 9 of the friction pair, an upper support layer 7 made of acrylic plate is bonded on the upper side of the upper half part, a lower electrode layer 11 made of copper foil is bonded on the lower side of the lower half part 10 of the friction pair, a lower support layer 12 made of acrylic plate is bonded on the lower side of the lower half part of the friction pair, and a sponge or rubber buffer layer 13 is arranged on the lower side of the lower half part of the friction pair. The upper electrode layer 8 and the lower electrode layer 11 are each provided with a wire 14.

When a train passes, due to train load and vibration, the steel rail 1 is displaced downward and then displaced upward to recover when the train passes. In the process, the friction nano-generator 5 generates a potential difference between the upper electrode layer 8 and the lower electrode layer 11 due to the electrostatic induction effect, and generates two times of pulse currents with opposite positive and negative polarities in an external circuit through the lead 14.

When the rail fastener is damaged, the supporting rigidity of the rail fastener is reduced, so that the displacement of the rail is increased when a train passes through the rail fastener, and different electric signals generated by the friction nano-generator 5 are generated.

As an example:

(1) manufacturing a correspondence table of the damage working condition of the fastener and the output electric signal of the friction nano generator: a finite element model for train-steel rail-track bed coupling calculation is established by adopting finite element software, steel rail displacement under various fastener damage working conditions is calculated, the steel rail displacement is substituted into a friction nano generator theoretical calculation formula, and proper initial clearance is selected for calculation to obtain a correspondence table of the fastener damage working conditions and the friction nano generator output electric signals.

(2) Monitoring the damage condition of the fastener: between the steel rail and the track bed of the actual operation track, the friction nanometer generator is installed at the middle position of every two fasteners, the monitored voltage is recorded, the corresponding working condition is searched in the fastener damage working condition and the friction nanometer generator output electric signal corresponding table, and meanwhile, the friction nanometer generators at a plurality of different positions are crossed and compared to calculate the fastener damage working condition.

The friction nano generator consists of a friction pair, an electrode layer, a supporting layer and a buffer layer.

The friction pair is composed of a top dielectric material layer and a bottom dielectric material layer, the top dielectric material layer and the bottom dielectric material layer are identical in area and opposite in polarity, the top dielectric material layer and the bottom dielectric material layer are completely paved in a film form and are parallel and opposite, and a certain initial gap is reserved between the dielectric films.

The electrode layer is composed of two copper foils, the two copper foils are respectively bonded to the top dielectric material layer and the bottom dielectric material layer and located on the outer sides of the friction pairs, and the copper foils are connected with leads which can output current.

The supporting layer is composed of two acrylic flat plates which are respectively bonded to the outer sides of two copper foils of the electrode layer, so that the friction pair and the electrode layer are kept flat.

The buffer layer is made of sponge or rubber materials and is positioned below the supporting layer below the buffer layer, so that the important effects of enhancing the energy harvesting efficiency of the generator, buffering the load of the train and protecting the safety of the friction nano generator structure are achieved.

The monitoring method comprises the following steps, wherein step 1 and step 2 are to manufacture a correspondence table of the damage working condition of the fastener and the output electric signal of the friction nano generator, and step 3 is to actually measure the damage of the fastener.

The monitoring method comprises the following steps:

step 1, steel rail displacement response calculation:

establishing a train-steel rail-track bed coupling calculation finite element model, wherein a train body adopts a 10-freedom-degree multi-rigid-body train model, namely the train body and a bogie consider vertical and nodding displacement, a wheel set only considers vertical displacement, and the bogie and the wheel set, and a carriage and the bogie are respectively connected by primary suspension and secondary suspension; the steel rail adopts a flexible solid model, fasteners below the steel rail are distributed in a scattered mode at equal intervals, and a spring-damping unit is adopted for simulation; the ballast bed and the lining adopt rigid models; the rail is in an ideal state, and the irregularity of the rail is not considered.

Selecting a plurality of fastener damage working conditions, wherein the fastener damage working conditions comprise the fastener damage number and the fastener damage position, and the rigidity value of the fastener and the steel rail separation is 0 when the fastener is damaged. And calculating through a train-steel rail-track bed coupling calculation finite element model to obtain a middle point position between the two fasteners, namely a steel rail displacement time course curve z (t) of the installation position of the friction nano generator.

Step 2, calculating an output signal of the friction nano generator:

the output signal of the friction nanogenerator is calculated according to the following formula

Wherein d is₀＝d₁/ε_r1+d₂/ε_r2Is an effective thickness constant, d₁(d₂) And ε_r1(ε_r2) The thickness and dielectric constant of nylon and PTFE, respectively; epsilon₀Sigma is the charge density of the surface of the dielectric material, R is the size of the external resistor, S is the area of the friction pair, D (t) is the clearance of the friction pair, and the dielectric constant in vacuum is calculated according to the following formula

And z (t) is the displacement of the steel rail at the monitoring position, A is the initial gap of the friction pair, and the value of the initial gap of the friction pair is calculated according to the calculation result, is larger than the displacement of the steel rail without fastener damage and is smaller than the displacement of the steel rail with a plurality of fasteners damage.

By adopting a numerical integration mode, the relationship between the output signal of the friction nano generator at the monitoring position and the damage number and position of the fastener can be obtained, a table corresponding to the damage condition of the fastener and the damage signal of the friction nano generator is manufactured, whether the output signal of the friction nano generator is close to that under different damage working conditions in the table is checked, if yes, the initial clearance of the friction pair is changed, each working condition is recalculated according to the initial clearance, and the table is manufactured.

In this example, 4 conditions were selected for calculation, fastener I damaged, fastener II damaged, fastener I, II damaged and no fastener damaged, respectively. The calculation results are shown in fig. 4, the output signals of the friction nano-generator under 4 working conditions have specificity, wherein the output voltage increases along with the increase of the number of damaged fasteners, and when a single fastener is damaged, the output signal voltage is greater when a fastener I closer to the friction nano-generator is damaged than when a fastener II farther from the friction nano-generator is damaged. Therefore, the corresponding signal table of the output of the friction nanometer generator corresponding to the damage number and the position of different fasteners can be manufactured. For example, in this example, the peak voltages of the tribo nanogenerator when no fastener damage, fastener I damage, fastener II damage, and fastener I \ II damage were 3.1V, 52.3V, 23.6V, and 109.2V, respectively, and the data was recorded for use in step 3.

Step 3, actually measuring the friction nano generator:

and (3) installing a plurality of friction nano generators between the steel rail and the track bed, and adopting initial gaps according to the initial gaps finally adopted in the step (2) at the middle positions of the two fasteners. And (3) regularly using the test vehicle to carry out constant-speed inspection in a non-operation period, wherein the vehicle body parameters and the driving parameters of the test vehicle are the same as those of the finite element model established in the step 1.

And extracting the output electric signal of the friction nano generator under the steel rail passed by the test vehicle, recording the output electric signal, finding out the damage working condition of the corresponding fastener, and obtaining the damage condition of the peripheral fastener measured by a single monitoring device. The joint is compared a plurality of friction nanometer generator monitoring operating mode, and the number and the position of fastener damage are finally confirmed.

For example, as shown in fig. 5, when a fastener fails, two friction nano-generators at two ends of the fastener sequentially output voltages of 23.6V, 52.3V and 23.6V respectively. Namely, during monitoring, if the output voltage of a certain friction nano generator is 52.3V, it is indicated that a damage exists in the first fastener adjacent to a certain side of the device, and other fasteners are not damaged. At this time, the reading of the friction nano-generator on the adjacent side can be read again, and if 52.3V is read, it indicates that the damaged fastener is located in the middle position of the two read friction nano-generators. If 23.6V is read, it indicates that the fastener damage is located on the side of the friction nano-generator which reads 52.3V for the first time and is far away from the device which reads 23.6V for the second time.