Railway bridge girder erection machine damage monitoring system and monitoring method based on acoustic emission technology

Abstract

The invention provides a railway bridge girder erection machine damage monitoring system and monitoring method based on the acoustic emission technology, and belongs to the technical field of nondestructive testing, the railway bridge girder erection machine damage monitoring system is characterized in that a bridge girder erection machine main beam and a bridge girder erection machine supporting leg transmit damage signals through a waveguide rod, and the waveguide rod is connected with the main beam and the bridge girder erection machine supporting leg in a welding mode; the waveguide rods are connected through connecting fasteners, and a coupling agent is smeared between every two adjacent waveguide rods; the black hole waveguide rods are connected to the two ends of the main beam waveguide rod through fasteners. The sensor is fixed at the end part of the black hole waveguide rod; a damage signal is captured by the sensor and then is collected by the acoustic emission signal collector; and finally, analyzing the signal to obtain the damage type of the bridge girder erection machine, and positioning the damage position. A new technology is provided for damage monitoring of the railway bridge girder erection machine, and compared with past damage detection, the monitoring system and method are wide in coverage range and high in sensitivity, labor dependence is reduced, and the long-term operation and maintenance cost of the bridge girder erection machine is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing, and in particular to a railway bridge erection machine damage monitoring system and method based on acoustic emission monitoring technology. Background Art

[0002] Railway bridge-erecting machines, crucial equipment in railway construction, are primarily used for the erection and installation of bridges. Due to their complex operating environments, heavy loads, and prolonged, high-intensity operation, key structural components (such as main beams and outriggers) are susceptible to damage such as cracks, deformation, and even breakage due to fatigue, overload, or external impact. If these damages are not promptly detected and addressed, they can lead to equipment failure and even serious safety accidents.

[0003] Traditional methods for detecting damage to railway bridge erection machines rely primarily on manual inspections and regular maintenance. Manual inspections typically detect damage through visual inspection, percussion and listening, or the use of simple detection tools such as ultrasonic detectors. However, these methods have the following limitations:

[0004] 1. Limited coverage: Manual inspections are difficult to fully cover all key parts of the bridge crane, especially internal structures or hard-to-reach areas;

[0005] 2. Low sensitivity: Manual inspections are difficult to detect minor or early-stage damage, resulting in potential risks not being addressed in a timely manner.

[0006] 3. Reliance on experience: The accuracy of test results is highly dependent on the experience and technical level of the inspectors, which may lead to subjectivity and the risk of misjudgment.

[0007] 4. Inefficiency: Manual inspections require a lot of time and manpower, and cannot achieve real-time monitoring, making it difficult to meet the efficient operation and maintenance needs of modern railway construction.

[0008] In recent years, nondestructive testing (NDT) technologies have been widely used in the field of engineering equipment monitoring. Acoustic emission (AE) monitoring, a dynamic NDT method, can monitor equipment damage in real time by capturing elastic wave signals released by materials under stress. AE technology, with its high sensitivity, wide coverage, and real-time monitoring capabilities, has been applied to the health monitoring of pressure vessels, bridges, wind turbines, and other equipment. However, its application in the field of damage monitoring for railway bridge erection machines is still in its infancy, and a systematic monitoring method and solution has yet to be established.

[0009] Therefore, developing a real-time damage monitoring method for railway bridge-erecting machines based on acoustic emission monitoring technology has important engineering significance and application value. This method can achieve comprehensive coverage and real-time monitoring of key parts of the bridge-erecting machine, improve the sensitivity and accuracy of damage detection, and reduce reliance on manual inspections, thereby significantly improving the safety and operation and maintenance efficiency of the bridge-erecting machine and reducing long-term operation and maintenance costs. Summary of the Invention

[0010] In view of the above situation, in order to improve the efficiency and accuracy of bridge-building machine damage monitoring and reduce the detection cost, the present invention provides a railway bridge-building machine damage monitoring system and monitoring method based on acoustic emission technology, which uses an acoustic emission collector to collect the acoustic emission signals generated during the operation of the bridge-building machine and analyze them to achieve the purpose of real-time monitoring of bridge-building machine damage.

[0011] A railway bridge erection machine damage monitoring system based on acoustic emission technology includes a bridge erection machine, wherein the bridge erection machine includes a left main beam of the bridge erection machine composed of a plurality of main beams with variable cross-sections connected on the left side, a right main beam of the bridge erection machine composed of a plurality of main beams with variable cross-sections connected on the right side, a bridge erection machine main beam composed of the left main beam of the bridge erection machine and the right main beam of the bridge erection machine, a plurality of transverse bridge erection machine legs, a No. 1 bridge erection machine leg, and a bolt plate composed of bolts and steel plates, wherein the bolt plates are multiple and installed at intervals on the inner bottom surfaces of the left main beam of the bridge erection machine and the right main beam of the bridge erection machine. The railway bridge erection machine damage monitoring system is characterized in that the railway bridge erection machine damage monitoring system includes:

[0012] Transverse monitoring units, the transverse monitoring units are arranged in two groups, respectively arranged inside the left main beam of the bridge erection machine and the right main beam of the bridge erection machine, and respectively located on the right side of the bottom of the corresponding left main beam of the bridge erection machine or the right main beam of the bridge erection machine in the same direction;

[0013] A vertical monitoring unit is arranged on the outside of the No. 1 bridge-building machine support leg and is located in the upper half of the No. 1 bridge-building machine support leg.

[0014] A method for monitoring damage of a railway bridge erecting machine based on acoustic emission technology, utilizing the railway bridge erecting machine damage monitoring system based on acoustic emission technology as claimed in claims 1-3, characterized in that it comprises:

[0015] S1: The lateral monitoring unit and the vertical monitoring unit are used to transmit the acoustic emission signals of the main beam and the No. 1 bridge-erecting machine leg during the operation of the bridge-erecting machine. An acoustic black hole waveguide (ABH) is connected to the end of the lateral monitoring unit. The acoustic emission signal is amplified by the acoustic black hole waveguide to ensure that the acoustic emission signal can be transmitted along the bridge-erecting machine steel beam to the piezoelectric ceramic sensor.

[0016] S2: Preprocessing the acoustic emission signal in S1 to separate the environmental vibration noise and the effective acoustic emission signal;

[0017] S3: Performing time domain analysis and frequency domain analysis on the acoustic emission signals separated in S2 to quantify the degree of damage using amplitude, energy, rise time, and impact quantity;

[0018] S4: constructing a damage classification model by performing machine algorithm learning on the acoustic emission signal separated in S2, inputting a time-frequency graph, and outputting a damage type;

[0019] S5: The damage location is calculated based on the time difference between the acoustic emission signal in any horizontal monitoring unit or vertical monitoring unit reaching the piezoelectric ceramic sensors at both ends thereof and the attenuation law of the signal energy.

[0020] The beneficial effects of the above technical solution are:

[0021] The present invention provides a system and method for real-time monitoring of bridge-building machine damage based on acoustic emission technology, which solves the problem of low efficiency of traditional detection methods, reduces the cost of bridge-building machine damage monitoring, increases the monitoring range, and reduces unnecessary waste of personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the overall process of the acoustic emission monitoring method of the present invention;

[0023] Figure 2 It is a perspective diagram of the overall arrangement of the acoustic emission monitoring system of the present invention;

[0024] Figure 3 This is a schematic diagram of the arrangement of waveguide rods at the main beam bolt plate of the present invention;

[0025] Figure 4 This is a schematic diagram of the fastener structure for directly connecting each section of the waveguide rod of the present invention;

[0026] Figure 5 This is a schematic diagram of the structure of the acoustic black hole waveguide rod of the present invention. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments and the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art before making creative work shall fall within the scope of protection of the present invention.

[0028] Example 1, as Figure 2As shown, in this embodiment, the bridge-building machine includes a left main beam 1 of the bridge-building machine which is internally connected by several main beams with variable cross-sections 3 on the left side, a right main beam 4 of the bridge-building machine which is internally connected by several main beams with variable cross-sections 5 on the right side, a main beam of the bridge-building machine composed of the left main beam 1 of the bridge-building machine and the right main beam 4 of the bridge-building machine, several transverse bridge-building machine legs, No. 1 bridge-building machine leg 2, and a bolt plate 6 composed of bolts 61 and steel plates 62. There are several bolt plates 6 which are installed at intervals on the inner bottom surfaces of the left main beam 1 of the bridge-building machine and the right main beam 4 of the bridge-building machine. This is the basic design structure of the railway bridge-building machine currently on the market.

[0029] like Figure 2-5 As shown, the present disclosure provides a railway bridge-erecting machine damage monitoring system based on acoustic emission technology, which is divided into a horizontal monitoring unit and a vertical monitoring unit.

[0030] Among them, there are two groups of lateral monitoring units, which are respectively arranged inside the left main beam 1 of the bridge-building machine and the right main beam 4 of the bridge-building machine, and are respectively located on the right side of the bottom of the corresponding left main beam 1 or right main beam 4 of the bridge-building machine in the same direction.

[0031] The lateral monitoring unit is assembled by a series waveguide rod group, a main beam U-shaped waveguide rod 11, a black hole waveguide rod 14, a piezoelectric ceramic sensor 8, an acoustic emission signal collector 10, and a data cable 9.

[0032] Among them, the series waveguide rod group is composed of several 4-meter-long main beam waveguide rods 7, which are spliced and assembled in pairs through fasteners 12, and a coupling agent is applied at the connection to increase the degree of coupling, so that the attenuation of the signal is minimized when it is transmitted between two adjacent main beam waveguide rods 7. The series waveguide rod group is welded to the contact point of the inner wall of the corresponding main beam left variable section 3 or the main beam right variable section 5, and the fasteners 12 are tightened by fixing screws 13 to install and connect the two semi-cylinders.

[0033] The main beam waveguide rod 7 is cylindrical in shape and its function is to guide and transmit the sound wave signal so that the acoustic emission signal can be transmitted to the sensor efficiently and accurately.

[0034] Among them, the main beam U-shaped waveguide rod 11 is made of a waveguide rod bent by a machine, presenting a structure with vertical bends at the openings on both sides of the U-shape. The three sides of its bottom are welded around the contact point of the upper end surface of the bolt plate 6, and the tops of the two vertically bent sides are welded to the bottom contact point of the series waveguide rod group.

[0035] During the actual operation of the railway bridge-building machine, due to the excessive weight of the high-speed railway box girder, the main beam will produce a certain degree of downward deformation, and the bolt plate 6 at the bottom of the main beam will produce a large bending stress, and the bolts may become loose or break. Therefore, the waveguide rod is bent into a U shape by a bending device to make a main beam U-shaped waveguide rod 11, and then the main beam U-shaped waveguide rod 11 is connected in series to the series waveguide rod group of the main beam, and the signal generated by the bolt damage is transmitted to the main beam waveguide rod 7 in the series waveguide rod group, and the bolt plate 6 is surrounded by the main beam U-shaped waveguide rod 11 to focus on monitoring the bolt plate 6 at the bottom of the main beam, so as to capture the defects caused by the bolts in time.

[0036] Among them, the black hole waveguide rod 14 is a rod with a flat end, i.e. the acoustic black hole part is 25 cm long and the other end is cylindrical. The total length is selected to be 50 cm, which is not easy to produce large deformation and can achieve better signal amplification effect. Both ends of the series waveguide rod group are installed and docked with one cylindrical end of a black hole waveguide rod 14 through fasteners 12.

[0037] The black hole waveguide rod 14 utilizes a power function gradient to gradually reduce the wave propagation velocity within it, ideally to zero, thereby achieving near-zero wave reflection. It is used to amplify the signals transmitted by the main beam waveguide rod 7. Designing the black hole waveguide rod 14 presents a challenge: if the acoustic black hole portion is too long, significant deformation may occur during installation and use. If the acoustic black hole portion is too short, the signal amplification function will be reduced. Therefore, after experimentation, a 50 cm total length black hole waveguide rod 14 with a 25 cm acoustic black hole portion was ultimately chosen, achieving both minimal deformation and excellent signal amplification. It is important to note that the black hole waveguide rods 14 are only installed at the ends of the tandem waveguide rod assembly. Because the main beam span is long, acoustic emission signals experience significant signal attenuation during propagation. Furthermore, the monitoring range at the first leg 2 is relatively small, so conventional waveguide rods can effectively transmit signals.

[0038] Among them, the sensing end of the piezoelectric ceramic sensor 8 is installed and connected to the flat end of the black hole waveguide rod 14, which is used to convert the acoustic signal amplified by the black hole waveguide rod into an electrical signal and perform secondary amplification processing to ensure the integrity of the captured acoustic emission signal.

[0039] The piezoelectric ceramic sensor 8 has high sensitivity and can detect slight structural damage.

[0040] The two ends of the acoustic emission signal collector 10 are electrically connected to the connection terminals of a piezoelectric ceramic sensor 8 via a data line 9 .

[0041] The acoustic emission signal collector 10 is used to amplify the acoustic signal generated by the acoustic emission collected by the piezoelectric ceramic sensor 8 and convert it into an electrical signal for transmission and storage in a terminal computer device.

[0042] The data line 9 is used to transmit the electrical signal converted by the piezoelectric ceramic sensor 8 to the acoustic emission signal collector 10 .

[0043] The length of the data cable 9 is customized according to the length of the main beam of the bridge erection machine.

[0044] In addition, the vertical monitoring unit is arranged on the outside of the No. 1 bridge-building machine leg 2 and is located in the upper half of the No. 1 bridge-building machine leg 2. It is assembled from a leg waveguide rod 15, a piezoelectric ceramic sensor 8, and an acoustic emission signal collector 10.

[0045] Among them, the support leg waveguide rod 15 is U-shaped and welded to the contact point of one side surface of the No. 1 bridge-building machine support leg 2; a piezoelectric ceramic sensor 8 is installed at each end of the U-shaped opening of the support leg waveguide rod 15, and is connected to the sensing end of the piezoelectric ceramic sensor 8; the two ends of the acoustic emission signal collector 10 are electrically connected to the wiring terminal of a piezoelectric ceramic sensor 8 through a data line 9.

[0046] The leg waveguide rod 15 is 110 cm away from the bottom of the main beam. It is made by bending several rods that are the same as the main beam waveguide rod 7 and splicing them through fasteners 12. It is also for transmitting sound wave signals so that the acoustic emission signals can be transmitted to the sensor efficiently and accurately.

[0047] It should be noted that the acoustic emission signal collector 10 in this experiment is a DS9 acoustic emission signal collector. A total of three sets of DS9 acoustic emission signal collectors were used, including one set for each of the two main beams, namely the left main beam 1 of the bridge-building machine and the right main beam 4 of the bridge-building machine, and a separate set for the No. 1 support leg 2. Due to the large attenuation of the acoustic emission signal, one acoustic emission signal collector cannot fully monitor the key parts of the bridge-building machine. Therefore, the main beam with larger deflection and the relatively weak No. 1 support leg are selected for monitoring.

[0048] Example 2, as Figure 1 As shown, this embodiment is a real-time monitoring method for bridge erection machine damage based on acoustic emission, based on the monitoring system of Example 1, which is divided into the following steps:

[0049] S1: Design waveguide rods of corresponding length and shape based on the measured dimensions of the bridge-building machine. The main beam in this experiment is 66.4m long, and a section of the main beam waveguide rod inside is 4m long. Each main beam waveguide rod is connected end to end by fasteners and welded to the main beam and support legs of the bridge-building machine. The bolt group is surrounded by the main beam U-shaped waveguide rod on the bolt plate at the main beam connection. The main beam U-shaped waveguide rod is connected in series to the series waveguide rod group formed by splicing the main beam waveguide rods.

[0050] S2: Black hole waveguide rods are connected to the two ends of the series-connected waveguide rod group along the entire length of the main beam via fasteners. However, due to the large structure of the bridge-erecting machine, the propagation distance of the damage acoustic emission signal in the structure is limited. Therefore, an acoustic black hole waveguide rod (ABH) is required to be connected to the end of the lateral monitoring unit. The acoustic black hole waveguide rod is used to amplify the acoustic emission signal, thereby better collecting the acoustic emission signal generated by damage during the operation of the bridge-erecting machine main beam and the No. 1 bridge-erecting machine leg. The acoustic black hole waveguide rod is a waveguide rod designed with a specific geometric shape. The length of the black hole waveguide rod here is selected to be 50 cm, so that it can enhance the intensity of the acoustic emission signal. The mathematical model of its acoustic emission signal enhancement efficiency is shown in the following formula:

[0051]

[0052] Where, η A is the acoustic emission signal enhancement efficiency, A withABH The maximum amplitude of the acoustic emission signal collected by the acoustic emission sensor arranged at the cut-off height of the acoustic black hole waveguide rod, A withoutABH The maximum amplitude of the acoustic emission signal collected by the acoustic emission sensor arranged at the end of the acoustic black hole waveguide rod that is not embedded in the acoustic black hole ensures that the acoustic emission signal can be transmitted along the steel beam of the bridge crane to the sensor.

[0053] S3: For the main beam, the piezoelectric ceramic sensor is fixed to the end of the black hole waveguide rod, and the acoustic emission signal generated during the operation of the bridge-building machine is collected through the DS9 acoustic emission collector; for the outrigger, the piezoelectric ceramic sensor is directly placed at the end of the outrigger waveguide rod to collect the damage signal.

[0054] S4: Preprocess the collected acoustic emission signals through acoustic emission signal analysis software, including using filtering technology (such as low-pass filtering, band-pass filtering) to remove high-frequency noise and low-frequency interference; intercept the effective acoustic emission signal segment according to the time or energy threshold.

[0055] S5: Extract key features from the preprocessed signal for subsequent damage identification and location, including time domain features, frequency domain features, and time-frequency domain features.

[0056] S6: Classify features and identify damage types using machine learning algorithms. Specifically, by constructing a deep neural network model or employing classic machine learning algorithms such as support vector machines and random forests, the time-frequency characteristics of preprocessed structural vibration signals or acoustic emission signals are analyzed. The signals are converted into time-frequency plots (such as wavelet time-frequency plots or short-time Fourier transform plots) as model input. Machine learning algorithms can automatically learn the characteristic damage patterns implicit in the time-frequency plots. Through hierarchical processing in the feature extraction and pattern recognition layers, a nonlinear mapping is achieved from the raw time-frequency images to damage type labels. Finally, the model is trained using historical data to improve recognition accuracy.

[0057] S7: Determine the location of the damage through the propagation characteristics of the acoustic emission signal. The specific method of use is the time difference positioning method, that is, the time difference between multiple sensors receiving the same signal is used to calculate the position of the signal source, or the damage position is determined through geometric relationships based on the propagation speed of the acoustic emission signal in the material. Specifically, assuming that the distance between the piezoelectric ceramic sensor S1 (denoted as Sensor-1) and the piezoelectric ceramic sensor S2 (denoted as Sensor-2) at both ends of a horizontal monitoring unit or a longitudinal monitoring unit is D, the arrival time of the signals received by Sensor-1 and Sensor-2 are expressed as T1 and T2 respectively, and the arrival time difference is ΔT = |T2-T1|. The distance d from the acoustic emission source to the piezoelectric ceramic sensor that receives the signal first can be determined based on the propagation speed v of the acoustic emission wave in the component, as shown in the following formula:

[0058]

[0059] The above technical solutions are preferred implementation schemes of the present disclosure, and are intended to provide technical guidance for professionals in the relevant technical field to fully understand and implement the present disclosure. It should be noted that those skilled in the art can implement various adaptive modifications or adjustments to the present solution based on the existing technical level and engineering practice experience, and these technical variations should be regarded as reasonable extensions of the technical concept of the present disclosure. The scope of protection of the present disclosure is not limited to the implementation scheme recorded in words, but should cover all technical solutions that are consistent with the technical features defined in the claims of the present disclosure and the core innovations disclosed in the specification. Any equivalent replacement or local improvement that does not deviate from the technical principles of the present disclosure shall fall within the scope of protection of the claims of the present disclosure.

Claims

1. A railway bridge-erecting machine damage monitoring system based on acoustic emission technology, comprising a bridge-erecting machine, wherein the bridge-erecting machine comprises a left main beam (1) of the bridge-erecting machine internally connected by a plurality of left main beam variable cross-sections (3), a right main beam (4) of the bridge-erecting machine internally connected by a plurality of right main beam variable cross-sections (5), a bridge-erecting machine main beam consisting of the left main beam (1) and the right main beam (4), a plurality of transverse bridge-erecting machine legs, a No. 1 bridge-erecting machine leg (2), and a bolt plate (6) consisting of bolts (61) and a steel plate (62), wherein the bolt plates (6) are multiple and are installed at intervals on the inner bottom surfaces of the left main beam (1) and the right main beam (4) of the bridge-erecting machine, and characterized in that: The railway bridge erection machine damage monitoring system comprises: Transverse monitoring units, the transverse monitoring units are in two groups, respectively arranged inside the left main beam (1) and the right main beam (4) of the bridge erection machine, and respectively located on the right side of the bottom of the corresponding left main beam (1) or the right main beam (4) of the bridge erection machine; A vertical monitoring unit is arranged outside the No. 1 bridge-erecting machine support leg (2) and is located at the upper half of the No. 1 bridge-erecting machine support leg (2).

2. The railway bridge erection machine damage monitoring system based on acoustic emission technology according to claim 1 is characterized in that: The lateral monitoring unit comprises: A series waveguide rod group, wherein the series waveguide rod group is formed by splicing and assembling a plurality of main beam waveguide rods (7) in pairs through fasteners (12), and a coupling agent is applied at the connection to increase the degree of coupling, so that the attenuation of the signal when transmitting between two adjacent main beam waveguide rods (7) is minimized, and the series waveguide rod group is welded to the inner wall contact position of the corresponding main beam left variable section (3) or main beam right variable section (5); A main beam U-shaped waveguide rod (11), wherein the main beam U-shaped waveguide rod (11) is a U-shaped structure with two openings on both sides being vertically bent, and three sides of the bottom thereof are welded around the contact portion of the upper end surface of the bolt plate (6), and the tops of the two vertically bent sides are welded to the contact portion of the bottom surface of the series waveguide rod group; A black hole waveguide rod (14), wherein the black hole waveguide rod (14) is a rod having a flat end, i.e., an acoustic black hole portion, with a length of 25 cm and a cylindrical end, and a total length of 50 cm. It is not easy to produce large deformation and can achieve a good signal amplification effect. Both ends of the series waveguide rod group are respectively mounted and docked with one cylindrical end of the black hole waveguide rod (14) through a fastener (12); A piezoelectric ceramic sensor (8), wherein a sensing end of the piezoelectric ceramic sensor (8) is mounted and connected to a flat end of the black hole waveguide rod (14), and is used to convert the acoustic signal amplified by the black hole waveguide rod into an electrical signal and perform secondary amplification processing to ensure the integrity of the captured acoustic emission signal; An acoustic emission signal collector (10), wherein both ends of the acoustic emission signal collector (10) are electrically connected to a connection terminal of the piezoelectric ceramic sensor (8) via a data line (9); A data line (9) is used to transmit the electrical signal converted by the piezoelectric ceramic sensor (8) to the acoustic emission signal collector (10).

3. The railway bridge erection machine damage monitoring system based on acoustic emission technology according to claim 2 is characterized in that: The vertical monitoring unit includes: A leg waveguide rod (15), the leg waveguide rod (15) is U-shaped and welded to a contact portion of a side surface of the No. 1 bridge-erecting machine leg (2); A piezoelectric ceramic sensor (8), wherein each of the two ends of the U-shaped opening of the leg waveguide rod (15) is provided with a piezoelectric ceramic sensor (8), and is connected to a sensing end of the piezoelectric ceramic sensor (8); An acoustic emission signal collector (10), wherein both ends of the acoustic emission signal collector (10) are electrically connected to a connection terminal of the piezoelectric ceramic sensor (8) via a data line (9).

4. A railway bridge erection machine damage monitoring method based on acoustic emission technology, using the railway bridge erection machine damage monitoring system based on acoustic emission technology as claimed in claims 1-3, characterized in that: include: S1: The lateral monitoring unit and the vertical monitoring unit are used to transmit the acoustic emission signals of the main beam and the No. 1 bridge-erecting machine leg during the operation of the bridge-erecting machine. An acoustic black hole waveguide (ABH) is connected to the end of the lateral monitoring unit. The acoustic emission signal is amplified by the acoustic black hole waveguide to ensure that the acoustic emission signal can be transmitted along the bridge-erecting machine steel beam to the piezoelectric ceramic sensor. S2: Preprocessing the acoustic emission signal in S1 to separate the environmental vibration noise and the effective acoustic emission signal; S3: Performing time domain analysis and frequency domain analysis on the acoustic emission signals separated in S2 to quantify the degree of damage using amplitude, energy, rise time, and impact quantity; S4: constructing a damage classification model by performing machine algorithm learning on the acoustic emission signal separated in S2, inputting a time-frequency graph, and outputting a damage type; S5: The damage location is calculated based on the time difference between the acoustic emission signal in any horizontal monitoring unit or vertical monitoring unit reaching the piezoelectric ceramic sensors at both ends thereof and the attenuation law of the signal energy.

5. The method for monitoring damage of a railway bridge erecting machine based on acoustic emission technology according to claim 4 is characterized in that: The S5 includes: recording the positions of the piezoelectric ceramic sensors at both ends of any horizontal monitoring unit or vertical monitoring unit as S1 and S2 respectively. When damage occurs at a certain position in the structure and an acoustic emission signal is generated, the signal will propagate toward the two ends of the waveguide rod at a certain speed v. Since the two piezoelectric ceramic sensors are at different distances from the damage position, the time it takes for the signal to reach the two piezoelectric ceramic sensors will be different. By measuring this time difference ΔT and the known signal propagation speed v, the distance relationship between the damage position and the two sensors can be calculated, thereby determining the damage position.

6. The method for monitoring damage of a railway bridge erecting machine based on acoustic emission technology according to claim 5 is characterized in that: The damage location determination specifically includes: assuming that the distance between sensor S1 and sensor S2 is D, the arrival times of the signals received by the piezoelectric ceramic sensors at both ends of any horizontal monitoring unit or vertical monitoring unit are represented as T1 and T2 respectively, and the arrival time difference is recorded as ΔT = |T2-T1|. Then, the distance d between the acoustic emission source and the piezoelectric ceramic sensor that receives the signal first can be determined based on the propagation speed v of the acoustic emission wave in the component, as shown in the following formula: 。

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