Vibration damping devices for railway roof space frames and methods for detecting bolt loosening and crack propagation.

Abstract

This invention belongs to the field of vibration damping and health monitoring of railway roof space frames, and discloses a vibration damping device for railway roof space frames and its detection method for bolt loosening and crack propagation. The vibration damping device includes a first, second, and third vibration damping module for pipes. The first vibration damping module is connected to the pipe clamp via a pipe clamp support, the second vibration damping module is connected between the pipe clamp and the pipe support, and the third vibration damping module is symmetrically connected between the branch pipes via vibration damping. The bolt loosening detection method is based on monitoring the loosening state of bolt ball joint connections under vibration excitation. A piezoelectric ceramic sensor (PTZ) and a related circuit board amplifier are respectively set in the upper right pipe clamp and the pipe support. Through the inverse and direct piezoelectric effects of the piezoelectric material, the peak value of the stress signal is used as an indicator to monitor the bolt loosening state. The crack propagation monitoring method is based on PTZ and neural network technology, and damage is determined by the admittance curve of the stress signal.

Description

Technical Field

[0001] This invention belongs to the field of vibration reduction and health monitoring of railway roof space frames, and particularly relates to a vibration reduction device for railway roof space frames and a method for detecting bolt loosening and crack propagation. Background Technology

[0002] Among numerous structural systems, spatial steel structures possess characteristics such as lightweight and high strength, uniform material composition, and high degree of assembly. Compared to other structures, the detachability, ease of installation, and rapid construction of steel structures have secured their important position in the construction field. Many railway roofs now utilize spherical node space frame structures. In the application scenario of railway stations, vibration is a significant factor affecting the service life of spherical node space frame structures. Furthermore, under long-term, complex, and variable environments and operating conditions, problems such as bolt loosening and crack propagation can easily occur.

[0003] Due to the large span of the space frame structure and the long-term use of railway roof space frames, the installation of vibration damping devices and the implementation of structural health monitoring are very difficult. Many methods of designing vibration damping supports are not applicable to space frame structures that are already in use. Therefore, a simple and efficient testing method is needed to detect whether the space frame structure, especially the node connections, is healthy.

[0004] In summary, it is necessary to design a vibration damping device suitable for railway roof grid structures and a method that can effectively detect bolt loosening and crack propagation. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a vibration damping device for railway roof space frames and a method for detecting bolt loosening and crack propagation. This vibration damping device can effectively reduce the vibration of railway roof space frames and extend the service life of the space frame structure. This detection method can obtain two types of information—bolt loosening and crack propagation—through a set of sensors, and it is easy to install and provides accurate detection.

[0006] This invention provides the following technical solution:

[0007] This vibration damping device is used for railway roof space frames. The railway roof space frame includes side branches, an upper branch, and ball joints. The side branches and the upper branch are fixedly connected to the ball joints. The entire device is symmetrical between the side branches and includes a first damping module, a second damping module, and a third damping module. The first damping module is connected to the upper and lower clamping pipes and fixed to the side branches. The second damping module is supported by the upper inner clamping pipe and is movably connected via a slide rail. The third damping module is connected to the upper inner clamping pipe via spring damping and supported by an elastic support column on the lower inner clamping pipe. Piezoelectric ceramics (PZT1) and related circuit boards and signal amplifiers are placed in the upper inner clamping pipe cavity, while piezoelectric ceramics (PZT2) and related circuit boards and signal amplifiers are placed in the upper branch pipe support.

[0008] As a further improvement of the present invention, the first shock absorption module includes an upper positioning pin, an upper top shaft, a spring, a lower top shaft, a lower positioning pin, and a side support arm. The upper positioning pin is connected to the upper outer clamping tube support arm hole through a slot. The upper positioning pin is connected to the upper top shaft, and the lower top shaft is connected to the lower positioning pin. The upper and lower top shafts are respectively equipped with a knob one and a knob two, which can control the length of the spring. The lower positioning pin is connected to the lower outer clamping tube support arm hole through a bottom post. The upper and lower positioning pins are respectively provided with a slot one and a slot two, and the upper and lower support arms can move up and down in the slots. The side support is fixed between the upper and lower support arms, and a spring is provided inside the sleeve.

[0009] As a further improvement of the present invention, the upper outer clamping tube support arm is provided with an upper outer clamping tube support arm hole and connected to the upper outer clamping tube support, the upper outer clamping tube is fixedly connected to the upper inner clamping tube, the slide rail is used to support and connect the second shock absorption module, and the square groove is used to connect the spring damping.

[0010] As a further improvement of the present invention, the lower outer clamping tube support arm is provided with a lower outer clamping tube support arm hole and connected to the lower outer clamping tube support, the lower outer clamping tube and the lower inner clamping tube are fixedly connected, and the circular groove is used to connect the elastic support.

[0011] As a further improvement of the present invention, the second shock-absorbing module is symmetrically distributed from left to right. The tube support houses electronic components such as sensors, circuit boards, and signal amplifiers. Vertical shock absorbers stand between the tube support and the base plate. The base plate can move left and right via a bottom slide rail. Lateral shock absorbers and elastic support columns are mounted on the top plate. The vertical shock absorbers consist of a vertical support column and spring two, while the lateral shock absorbers consist of a horizontal support column and spring three. The lower panel of the elastic support column is fixed to the top plate and consists of a sliding surface, a main support column, and an elastic sleeve. Openings on the side panels are used to fix the lateral shock absorbers.

[0012] As a further improvement of the present invention, the spring damping is fixedly connected to the square plate and the square groove, and is connected to the square buffer plate and the support plate fixing pin one. The slot is connected to the fixing pin one, the circular buffer plate is connected to the spring support, the spring four abuts against the circular buffer plate, the lower end of the spring support is fixed to the circular groove, and the fixing pin two is used to connect with the fixing block.

[0013] As a further improvement of the present invention, the elastic support is connected to the circular plate and the circular groove, the first bolt fixes the square fixed plate and the movable block, the large washer is used for buffering the square fixed plate, the small washer is used for buffering the movable block, the second bolt connects the bolt washer plate and the flexible block, and the base column is connected to the flexible block through the circular groove.

[0014] As a further improvement of the present invention, the third shock absorption module includes a fixed block, a fixed block connector and a shock absorption center, a U-shaped groove connected to a spring damping, a circular fixed groove connected to an elastic support, and a fixed block connector connecting the fixed block and the shock absorption center through a sliding groove.

[0015] As a further improvement of the present invention, the shock-absorbing center is mainly composed of an upper clamping plate, a lower clamping plate and a side support plate. The square hole is used to connect the fixing block connector, the column is used for counterweight in different directions, the counterweight block is connected to the lateral support, the flexible rod connects the lateral support and the cavity, the cavity is used for air shock absorption, and the bearing connects the lower rotating block.

[0016] Another object of the present invention is to provide a method for monitoring bolt loosening in a space frame structure, based on the above-mentioned device, comprising the following steps:

[0017] S11. Place the piezoelectric ceramic (PZT1) in the upper inner clamp cavity and the piezoelectric ceramic (PZT2) in the upper branch pipe support.

[0018] S12. Confirm the connection status of the sensor. The corresponding signal amplifier, receiver and computer need to be connected.

[0019] S13. When there is vibration excitation, the inverse piezoelectric effect of PZT1 converts electrical energy into mechanical energy. The stress wave signal generated by PZT1 using this characteristic will be transmitted from the ball joint through the bolt at the intersection of the joint and the pipe to the pipe until PZT2 receives the stress wave signal and the first signal transmission is completed.

[0020] After receiving the stress wave signal, S14 and PZT2 utilize their characteristics as both sensors and actuators, and due to time reversal characteristics, PZT2 converts mechanical energy into electrical energy through the positive voltage effect, and transmits the electrical energy as a new signal to PZT1.

[0021] The positive voltage effect of S15 and PZT2, and the inverse voltage effect of PZT1, are jointly transmitted to the wave source signal to form a focused signal. By comparing the focused signal under healthy conditions with the focused signal under damaged conditions, if the comparison is consistent, it indicates that no damage has occurred; if the comparison is inconsistent, it indicates that the bolts at the node and pipe connection have become loose.

[0022] It should be noted that the initial signal The relationship with the focusing signal is In the formula, C is the transfer function of the structure itself, and the initial signal is the signal generated by the roof vibration.

[0023] Another objective of this invention is to provide a method for detecting crack propagation in a space frame structure, based on the aforementioned working principle of piezoelectric ceramics, comprising the following steps:

[0024] S21. Place the piezoelectric ceramic (PZT1) in the upper inner clamp cavity and the piezoelectric ceramic (PZT2) in the upper branch pipe support.

[0025] S22. Confirm the connection status of the sensor. The corresponding signal amplifier, receiver and computer need to be connected.

[0026] S23. Since there is a coupling relationship between the mechanical resistance of the structure and the admittance value of PZT, the change in the admittance value of PZT sheet can reflect structural damage and obtain stress wave signals in healthy and damaged states.

[0027] S24. Determine the sensitive segment based on the admittance curve under healthy operating conditions, and compare the sensitive segment under damaged operating conditions with the sensitive segment under healthy operating conditions to determine whether damage has occurred.

[0028] S25, Formula As a damage assessment indicator, the processed admittance value is input into the BP neural network, where... The signal energy value collected under healthy conditions. denoted as the signal energy value acquired under real-time damage conditions, where i is the frequency point.

[0029] S26. The neural network is trained with a large number of samples to establish a BP neural network, determine the structural design and parameter selection, and finally complete the identification of damage.

[0030] Compared with the original technology, the present invention can directly install a vibration damping device between the ball node and the pipe without changing the space frame structure. The vibration damping device has a good vibration damping effect, which can greatly extend the service life of the steel structure. Furthermore, it proposes an efficient detection method that can obtain two information: bolt loosening and crack propagation, using a set of piezoelectric sensors. This greatly reduces the consumption of manpower and time, and ensures the personal safety of construction personnel, making it highly practical. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall device of the railway roof grid vibration damping device of the present invention.

[0032] Figure 2 This is a schematic diagram of the first damping module of the railway roof grid damping device of the present invention.

[0033] Figure 3 This is a schematic diagram of the upper clamping tube of the railway roof grid shock absorption device of the present invention.

[0034] Figure 4 This is a schematic diagram of the lower clamping pipe of the railway roof grid vibration damping device of the present invention.

[0035] Figure 5 This is a schematic diagram of the second damping module of the railway roof grid damping device of the present invention.

[0036] Figure 6 The diagram above shows the second damping module of the railway roof grid damping device of the present invention.

[0037] Figure 7 This is a detailed schematic diagram of the elastic support column of the railway roof grid shock absorption device of the present invention.

[0038] Figure 8 This is a schematic diagram of the third damping module of the railway roof grid damping device of the present invention.

[0039] Figure 9 This is a schematic diagram of the overall damping center of the railway roof grid shock absorption device of the present invention.

[0040] Figure 10 This is an exploded schematic diagram of the spring damping mechanism of the railway roof grid shock absorption device of the present invention.

[0041] Figure 11 This is a schematic diagram of the explosive projection of the elastic support column of the railway roof grid shock absorption device of the present invention.

[0042] Figure 12 This is a stress wave focusing signal diagram for detecting loose bolts on a railway roof grid structure according to the present invention.

[0043] Figure 13 This is a flowchart of the railway roof grid bolt loosening detection method of the present invention.

[0044] Figure 14 This is a flowchart of the railway roof grid crack propagation detection method of the present invention. Detailed Implementation

[0045] The technical solutions in the implementation are described clearly and completely below with reference to the accompanying drawings in the examples of the present invention. The described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] This invention provides a vibration damping device for railway roof space frames, such as... Figure 1 As shown, the railway roof grid structure includes side branch pipes 3, upper branch pipes 1, and ball joints 2. Side branch pipes 3 and upper branch pipes 1 are fixedly connected to ball joints 2. The entire device is symmetrical between the side branch pipes and includes a first damping module, a second damping module, and a third damping module. The first damping module 4 is connected to the upper clamping pipe 5 and the lower clamping pipe 6 and fixed to the side branch pipe 3. The second damping module 7 is supported on the upper inner clamping pipe 5-5 and is movably connected via a slide rail 5-7. The third damping module 9 is connected to the upper inner clamping pipe 5-5 via a spring damper 8 and supported on the lower inner clamping pipe 6-5 via an elastic support column 10. The piezoelectric ceramic PZT1 and related circuit boards and signal amplifiers are placed in the upper inner clamping pipe cavity 5-6, and the piezoelectric ceramic PZT2 and related circuit boards and signal amplifiers are placed in the pipe support 7-1 of the upper branch pipe 1.

[0047] like Figure 2As shown, the first damping module 4 includes an upper positioning pin 4-2, an upper top shaft 4-4, a spring 4-5, a lower top shaft 4-6, a lower positioning pin 4-8, and a side support arm 4-11. The upper positioning pin 4-2 is connected to the upper outer clamping tube support arm hole 5-2 via a slot 4-1. The upper positioning pin 4-2 is connected to the upper top shaft 4-4, and the lower top shaft 4-6 is connected to the lower positioning pin 4-8. The upper top shaft 4-4 and the lower top shaft 4-6 are respectively equipped with a knob 4-3 and a knob 4-7, which can control the length of the spring 4-5. The lower positioning pin 4-8 is connected to the lower outer clamping tube support arm hole 6-2 via a base post 4-16. The upper positioning pin 4-2 and the lower positioning pin 4-8 are respectively provided with slot 1 4-10 and slot 2 4-15. The upper support arm 4-9 and the lower support arm 4-14 can move up and down in the slots. The side support 4-13 is fixed between the upper support arm 4-9 and the lower support arm 4-14. A spring is provided inside the sleeve 4-12.

[0048] like Figure 3 As shown, the upper outer clamping tube support arm 5-1 has an upper outer clamping tube support arm hole 5-2 and is connected to the upper outer clamping tube support 5-3. The upper outer clamping tube 5-4 is fixedly connected to the upper inner clamping tube 5-5. The slide rail 5-7 is used to support and connect the second shock absorption module 7. The square groove 5-8 is used to connect the spring damper 8.

[0049] like Figure 4 As shown, the lower outer clamping tube support arm 6-1 has a lower outer clamping tube support arm hole 6-2 and is connected to the lower outer clamping tube support 6-3. The lower outer clamping tube 6-4 is fixedly connected to the lower inner clamping tube 6-5. The circular groove 6-6 is used to connect the elastic support column 10.

[0050] like Figure 5 , Figure 6 , Figure 7 As shown, the second damping module 7 is symmetrically distributed from left to right. The tube support 7-1 houses electronic components such as sensors, circuit boards, and signal amplifiers. The vertical damping module 7-2 stands between the tube support 7-1 and the base plate 7-4. The base plate 7-4 can move left and right via a bottom slide rail. The horizontal damping module 7-6 and the elastic support column 7-5 are mounted on the top plate 7-3. The vertical damping module 7-2 consists of a vertical support column 7-1-2 and a second spring 7-1-1. The horizontal damping module 7-6 consists of a horizontal support column 7-6-1 and a third spring 7-6-2. The lower panel of the elastic support column 7-5 is fixed to the top plate 7-3 and is composed of a sliding surface 7-5-4, a main support column 7-5-3, and an elastic sleeve 7-5-2. The opening 7-5-6 on the side plate 7-5-5 is used to fix the horizontal damping module 7-6.

[0051] like Figure 8 , Figure 9As shown, the third damping module 9 includes a fixed block 9-1, a fixed block connector 9-4, and a damping center 9-5. A U-shaped groove 9-2 connects to the spring damper 8, and a circular fixed groove 9-3 connects to the elastic support column 10. The fixed block connector 9-4 connects the fixed block 9-1 and the damping center 9-5 via a sliding groove. The damping center 9-5 is mainly composed of an upper clamping plate 9-6-1, a lower clamping plate 9-6-3, and a side support plate 9-6-4. A square hole 9-6-2 is used to connect the fixed block connector 9-4. The column 9-6-5 is used for counterweights in different directions. The counterweight block 9-6-6 connects to the lateral support 9-6-7. A flexible rod 9-6-8 connects the lateral support to the cavity 9-6-9, which is used for air damping. The bearing 9-6-10 connects to the lower rotating block 9-6-11.

[0052] like Figure 10 As shown, the spring damper 8 is fixedly connected to the square groove 5-8 via the square plate 8-1, and is interconnected with the square buffer plate 8-2, the support plate 8-3, and the fixing pin 8-4. The slot 8-5 is connected to the fixing pin 8-4. The circular buffer plate 8-6 is connected to the spring support 8-7. The spring 8-8 rests on the circular buffer plate 8-6. The lower end of the spring support 8-7 is fixed to the circular groove 8-9. The fixing pin 8-10 is used to connect with the fixing block 9-1.

[0053] like Figure 11 As shown, the elastic support 10 is connected to the circular groove 6-6 via the circular plate 10-1. Bolt 10-5 fixes the square fixed plate 10-2 and the movable block 10-6. The large washer 10-3 is used to buffer the square fixed plate 10-2, and the small washer 10-4 is used to buffer the movable block 10-6. Bolt 2 10-8 connects the bolt washer 10-7 and the flexible block 10-9. The base column 10-11 is connected to the flexible block 10-9 via the circular groove 10-10.

[0054] Figure 12 This is a focused signal diagram of stress waves for bolt loosening detection. Figure 13 This is a flowchart of the method for detecting loose bolts on a space frame, based on... Figure 12 , 13Piezoelectric ceramic (PZT1) is placed on the ball node 2 of the grid structure, and piezoelectric ceramic (PZT2) is placed on the pipe 4 behind the pipe damper 5. The connection status of the sensors needs to be confirmed, requiring the connection of the corresponding signal amplifier, receiver, and computer. When a train passes through the station, vibration excitation is generated. At this time, the inverse piezoelectric effect of PZT1 converts electrical energy into mechanical energy. The stress wave signal generated by PZT1 using this characteristic will be transmitted from the ball node through the bolt at the intersection of the node and the pipe, and then to the pipe, until PZT2 receives the stress wave signal and the first signal transmission is completed. After receiving the stress wave signal, PZT2, utilizing its characteristic of being both a sensor and an actuator, and through time-reversal technology, converts the mechanical energy into electrical energy using a positive voltage effect, transmitting the electrical energy as a new signal to PZT1. The positive voltage effect of PZT2 and the inverse voltage effect of PZT1 are jointly transmitted to the wave source signal to form a focused signal. The focused signals are categorized and compared between signals from a healthy state and signals from a damaged state. If the two signals match, it indicates that no damage has occurred; if they do not match, it indicates that the bolts at the node and pipe connection have loosened. It should be noted that the initial signal... With focus signal The relationship is In the formula, C is the transfer function of the structure itself.

[0055] Figure 14 This is a flowchart of a crack propagation detection method, based on... Figure 14 The process is as follows: piezoelectric ceramic (PZT1) is placed on the ball node 2 of the space frame, and piezoelectric ceramic (PZT2) is placed on the pipe 4 behind the pipe damper 5. After attaching the sensors, confirm their connection status, requiring connection of the corresponding signal amplifier, receiver, and computer. Since there is a coupling relationship between the mechanical resistance of the structure and the admittance value of the PZT, changes in the admittance value of the PZT sheet can reflect structural damage. Based on the positive and negative voltage effects of PZT1 and PZT2, stress wave signals under healthy and damaged conditions are obtained. Sensitive segments are determined based on the admittance curve under healthy conditions. The sensitive segments under damaged conditions are compared with those under healthy conditions to determine if damage has occurred. The formula is then used... As a damage assessment indicator, the processed admittance value is input into a backpropagation (BP) neural network. The network is trained on a large number of samples to establish the BP neural network structure, determine its design and parameter selection, and ultimately identify the damage.

[0056] The specific implementation methods described above further illustrate the technical solution and beneficial effects of the present invention. It should be understood that the above description is a specific embodiment of the present invention, and any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A damping device for a railway canopy grid, characterized in that: The railway roof grid includes a side branch pipe (3), an upper branch pipe (1), and a ball joint (2). The side branch pipe (3) and the upper branch pipe (1) are fixedly connected to the ball joint (2). The device is symmetrical between the side branch pipes (3) and includes a first damping module (4), a second damping module (7), and a third damping module (9). The first damping module (4) is connected to the upper clamping pipe (5) and the lower clamping pipe (6) and fixed to the side branch pipe (3). The second damping module (7) is carried on the upper inner clamping pipe (5-5) and is movably connected by the slide rail (5-7). The third damping module (9) is connected to the upper inner clamping pipe (5-5) by the spring damper (8) and supported by the lower inner clamping pipe (6-5) by the elastic support (10). The piezoelectric ceramic PZT1 and the circuit board and the signal amplifier are placed in the upper inner clamping pipe cavity (5-6). The piezoelectric ceramic PZT2 and the circuit board and the signal amplifier are placed in the pipe support (7-1) of the upper branch pipe (1).

2. The damping device for railway roof grid according to claim 1, characterized in that: The first shock absorption module (4) includes an upper positioning pin (4-2), an upper top shaft (4-4), a spring (4-5), a lower top shaft (4-6), a lower positioning pin (4-8), and a side support arm (4-11). The upper positioning pin (4-2) is connected to the upper outer clamping tube support arm hole (5-2) through a slot (4-1). The upper positioning pin (4-2) is connected to the upper top shaft (4-4), and the lower top shaft (4-6) is connected to the lower positioning pin (4-8). The upper top shaft (4-4) and the lower top shaft (4-6) are respectively equipped with a knob (4-3). The second knob (4-7) is used to control the length of the first spring (4-5); the lower positioning pin (4-8) is connected to the lower outer clamping tube support arm hole (6-2) through the bottom post (4-16); the upper positioning pin (4-2) and the lower positioning pin (4-8) are respectively provided with slot one (4-10) and slot two (4-15), the upper support arm (4-9) and the lower support arm (4-14) can move up and down in the slots, the side support (4-13) is fixed between the upper support arm (4-9) and the lower support arm (4-14), and the sleeve (4-12) is provided with a spring.

3. The vibration damping device for railway roof space frame according to claim 1, characterized in that: The upper outer clamping tube support arm (5-1) has an upper outer clamping tube support arm hole (5-2) and is connected to the upper outer clamping tube support (5-3). The upper outer clamping tube (5-4) is fixedly connected to the upper inner clamping tube (5-5). The slide rail (5-7) is used to support and connect the second shock absorption module (7). The square groove (5-8) is used to connect the spring damper (8). The lower outer clamping tube support arm (6-1) has a lower outer clamping tube support arm hole (6-2) and is connected to the lower outer clamping tube support (6-3). The lower outer clamping tube (6-4) is fixedly connected to the lower inner clamping tube (6-5). The circular groove (6-6) is used to connect the elastic support column (10).

4. The vibration damping device for railway roof space frame according to claim 1, characterized in that: The second shock absorption module (7) is symmetrically distributed from left to right. The tube support (7-1) contains sensors, circuit boards, signal amplifiers, and electronic components. The vertical shock absorber (7-2) stands between the tube support (7-1) and the base plate (7-4). The base plate (7-4) can move left and right via the bottom slide rail. The horizontal shock absorber (7-6) and the elastic support column (7-5) are set on the top plate (7-3). The vertical shock absorber (7-2) is supported by vertical support columns (7-1-2). It consists of spring 2 (7-1-1), and the transverse damping (7-6) consists of transverse support column (7-6-1) and spring 3 (7-6-2); the lower panel of the elastic support column (7-5) is fixed on the top plate (7-3) and is composed of sliding surface (7-5-4), main support column (7-5-3) and elastic sleeve (7-5-2); the opening (7-5-6) on the side plate (7-5-5) is used to fix the transverse damping (7-6).

5. The vibration damping device for railway roof space frame according to claim 1, characterized in that: The spring damper (8) is fixedly connected to the square groove (5-8) via the square plate (8-1), and is connected to the square buffer plate (8-2) and the support plate (8-3) via the fixing pin one (8-4). The slot (8-5) is connected to the fixing pin one (8-4). The circular buffer plate (8-6) is connected to the spring support column (8-7). The spring four (8-8) abuts against the circular buffer plate (8-6). The lower end of the spring support column (8-7) is fixed to the circular groove (8-9). The fixing pin two (8-10) is used to connect with the fixing block (9-1).

6. The vibration damping device for railway roof space frame according to claim 1, characterized in that: The elastic support (10) is connected to the circular groove (6-6) through the circular plate (10-1). Bolt 1 (10-5) fixes the square fixed plate (10-2) and the movable block (10-6). The large washer (10-3) is used for buffering the square fixed plate (10-2). The small washer (10-4) is used for buffering the movable block (10-6). Bolt 2 (10-8) connects the bolt washer plate (10-7) and the flexible block (10-9). The base column (10-11) is connected to the flexible block (10-9) through the circular groove (10-10).

7. The vibration damping device for railway roof space frame according to claim 1, characterized in that: The third damping module (9) includes a fixed block (9-1), a fixed block connector (9-4), and a damping center (9-5). The fixed block (9-1) is connected to the spring damper (8) through a U-shaped groove (9-2) and to the elastic support (10) through a circular fixed groove (9-3). The fixed block connector (9-4) connects the fixed block (9-1) and the damping center (9-5) through a sliding groove. The damping center (9-5) consists of an upper clamping plate (9-6-1) and a lower clamping plate (9-6-1). It consists of a plate (9-6-3) and a side support plate (9-6-4). A square hole (9-6-2) is used to connect the fixing block connector (9-4). A column (9-6-5) is used for counterweights in different directions. The counterweight block (9-6-6) is connected to the transverse support (9-6-7). A flexible rod (9-6-8) connects the transverse support to the cavity (9-6-9). The cavity (9-6-9) is used for air shock absorption. A bearing (9-6-10) is connected to the lower rotating block (9-6-11).

8. A method for detecting bolt loosening in railway roof space frames, characterized in that, The vibration damping device for railway roof space frame according to any one of claims 1-7 includes the following steps: S11. Place the piezoelectric ceramic PZT1 in the upper inner clamp cavity (5-6) and the piezoelectric ceramic PZT2 in the pipe support (7-1) of the upper branch pipe (1); S12. Confirm the connection status of the sensor. The corresponding signal amplifier, receiver and computer need to be connected. S13. When there is vibration excitation, the inverse piezoelectric effect of the piezoelectric ceramic PZT1 converts electrical energy into mechanical energy. The stress wave signal generated by the piezoelectric ceramic PZT1 using this characteristic will be transmitted from the ball node through the bolt at the intersection of the node and the pipe to the pipe until the piezoelectric ceramic PZT2 receives the stress wave signal and the first signal transmission is completed. S14. After receiving the stress wave signal, the piezoelectric ceramic PZT2 utilizes its characteristic of being both a sensor and an actuator. Due to the time reversal characteristic, the piezoelectric ceramic PZT2 converts mechanical energy into electrical energy through the positive voltage effect, and transmits the electrical energy as a new signal to the piezoelectric ceramic PZT1. S15, the positive voltage effect of piezoelectric ceramic PZT2 and the reverse voltage effect of piezoelectric ceramic PZT1 are jointly transmitted to the wave source signal to form a focused signal; compare the focused signal under healthy condition and the focused signal under damaged condition. If the comparison is consistent, it means that no damage has occurred. If the comparison is inconsistent, it means that the bolts at the node and pipe connection have become loose.

9. The bolt loosening detection method for railway roof space frame according to claim 8, characterized in that: initial signal With focus signal The relationship is In the formula, C is the transfer function of the structure itself, and the initial signal is the signal generated by the roof vibration.

10. A method for detecting crack propagation in railway roof space frames, characterized in that, The vibration damping device for railway roof space frame according to any one of claims 1-7 includes the following steps: S21. Place the piezoelectric ceramic PZT1 in the upper inner clamp cavity (5-6) and the piezoelectric ceramic PZT2 in the pipe support (7-1) of the upper branch pipe (1); S22. Confirm the connection status of the sensor. The corresponding signal amplifier, receiver and computer need to be connected. S23. Since there is a coupling relationship between the mechanical resistance of the structure and the admittance value of the piezoelectric ceramic PZT, the change in the admittance value of the piezoelectric ceramic PZT sheet can reflect structural damage and obtain stress wave signals in healthy and damaged states. S24. Determine the sensitive segment based on the admittance curve under healthy operating conditions, and compare the sensitive segment under damaged operating conditions with the sensitive segment under healthy operating conditions to determine whether damage has occurred. S25, Formula As a damage assessment indicator, the processed admittance value is input into the BP neural network, where... The signal energy value collected under healthy conditions. is the signal energy value collected under real-time damage conditions, where i is the frequency point; S26. The neural network is trained with a large number of samples to establish a BP neural network, determine the structural design and parameter selection, and finally complete the identification of damage.

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