Non-stationary vibration signal acquisition and analysis system for simulating linear time-varying structure of trolley gap bridge

Abstract

The invention provides a system for health monitoring and dynamic analysis of a bridge structure. The system is particularly suitable for collecting and analyzing non-stationary vibration signals of a linear time-varying structure for simulating trolley bridge crossing. The system comprises a time-varying structure, an excitation system, a multi-mode sensor, a measurement and analysis system, a motor system, a dynamic parameter control module and a signal processing module. Bridge structures with different time-varying characteristics are simulated by changing the mass size and the movement mode of the mass block. The two ends of the bridge are fixed to the top end of the supporting table body through screws, and the middle of the bridge is suspended. The vibration exciter makes contact with a bridge supporting body, and the motor system controls the movement mode of the movable mass block. The multi-mode sensor is vertically arranged on the bottom face of a bridge, and parameters of the mass block and the bridge are adjusted in real time through the dynamic parameter control module. The signal processing module can quickly acquire the dynamic response of the system by combining a real-time feedback control mechanism with signal analysis technologies such as wavelet transform and the like, and errors are reduced. The system effectively solves the problem that a traditional experimental device cannot accurately simulate a linear time-varying structure of a trolley gap bridge, and the dynamic monitoring and analysis capability of the bridge structure is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of simulation experiments and dynamic characteristics monitoring of linear time-varying structures, and is particularly suitable for health monitoring and dynamic response analysis of bridge structures under complex working conditions. Specifically, the present invention combines a multimodal sensor array with real-time feedback control technology to accurately monitor the dynamic characteristics of bridges in extreme environments (such as strong winds, heavy rains and other weather conditions) or high-frequency loads (such as large freight vehicles passing frequently). Through the pressure, strain, acceleration and other data collected by multimodal sensors, the system can provide real-time feedback on the structural status of the bridge to ensure bridge safety and performance optimization under complex working conditions. Background Art

[0002] In practical engineering applications, structural properties often change significantly over time, especially in aerospace, mechanical equipment and bridge engineering, where this time-varying characteristic is particularly prominent. For example, the mass change caused by fuel consumption during rocket launch, the aerodynamic heating effect of the aircraft during high-speed flight, and the mass and stiffness changes when the solar panels of the spacecraft are deployed, all have an impact on the dynamic characteristics of the structure. In bridge engineering, the dynamic load changes when trains and trucks pass through the bridge will also significantly affect the vibration characteristics of the bridge structure. Traditional experimental methods mostly rely on static or quasi-static simulation methods, which cannot accurately capture the non-stationary vibration signals of the structure under actual working conditions. However, the time-varying structural simulation of the existing technology mostly only changes the speed and position of the mass block, and the signal acquisition is mostly limited to a single sensor type, making it difficult to obtain complete dynamic response data. Therefore, in order to improve the accuracy of dynamic analysis of complex structures such as bridges, there is an urgent need for a system that can combine multi-modal sensors and has real-time feedback capabilities to more accurately simulate and analyze the dynamic behavior of linear time-varying structures.

[0003] In view of this, this application is filed. Summary of the invention

[0004] The present invention provides a non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge, which combines a multi-modal sensor array and real-time feedback control technology to improve the monitoring accuracy of bridge structures in complex environments. The multi-modal sensors in the system can collect multi-dimensional data such as pressure, strain, acceleration and temperature of the bridge structure, so as to more comprehensively reflect the response characteristics of the bridge under dynamic conditions, especially in extreme weather conditions (such as strong winds, heavy rains) and high-frequency, high-load vehicles passing through. The system can adjust the parameters of the bridge structure through a real-time feedback mechanism to ensure the safe operation of the bridge structure under complex working conditions. The system is applicable to a variety of bridge types (such as highway bridges, railway bridges, cable-stayed bridges, etc.), and can adjust the monitoring plan according to the actual working environment of the bridge, providing an important reference for the design, maintenance and health assessment of the bridge.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The non-stationary vibration signal acquisition and analysis system of the linear time-varying structure simulating a trolley crossing a bridge of the present invention is widely applicable to the health monitoring and dynamic response analysis of bridges. The system can adapt to various types of bridges, including highway bridges, railway bridges, cable-stayed bridges and long-span bridges. By dynamically adjusting the motion form and excitation signal of the mass block, the system can capture the non-stationary vibration signal of the bridge in real time under heavy load conditions such as fully loaded trucks and trains, and then perform high-precision modal analysis, which is particularly suitable for long-term health monitoring and dynamic evaluation of bridge structures.

[0007] The system collects vibration signals through a multimodal sensor array, and shows high adaptability and analysis accuracy when dealing with the dynamic response of bridges under different loads such as large trucks, trains and small vehicles. It is particularly suitable for health assessment and maintenance of complex bridge structures.

[0008] A non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a trolley crossing a bridge, comprising: a time-varying structure, an excitation system, a multimodal sensor assembly, a measurement and analysis system, a motor system and a support platform, wherein the time-varying structure comprises a bridge and a mobile mass block, the excitation system is arranged on the ground, the exciter top rod of the excitation system is in contact with the support body of the bridge, the multimodal sensor assembly is vertically placed on the bottom surface of the bridge, the support platform is placed on the horizontal ground, the support platform comprises a first platform and a second platform, the first platform is used to support the bridge, the second platform is used to support the motor system, and the two ends of the bridge are connected to the motor system. The ends are fixed at the front and rear ends of the top of the first platform, the mobile mass block is connected to the motor system through a steel plate, the motor system is installed on the left side and the top of the second platform, the multimodal sensor assembly is connected to the measurement and analysis system, the dynamic parameter control module adjusts the various parameters of the mass block and the bridge in real time to more accurately simulate the driving process of different vehicles, and the signal processing module can perform time-frequency analysis and modal identification on the collected data by introducing sensor-based modal analysis and noise filtering technology, and can obtain the dynamic response of the system more quickly, reduce errors, and ensure high-precision analysis of the system under dynamic conditions;

[0009] The time-varying structure configuration can change various parameters of the moving mass block and the bridge through a dynamic parameter control module to simulate vehicles in different working conditions, and the motor system is configured to control the movement of the moving mass block to achieve a time-varying structure simulating different time-varying characteristics;

[0010] The measurement and analysis system is configured to implement the following steps by executing a computer program stored therein:

[0011] Acquire the vibration signals of the bridge under different excitation conditions collected by the multimodal sensor assembly, and combine multimodal sensors, including pressure sensors, strain sensors, and temperature sensors, to perform real-time monitoring in more dimensions;

[0012] The collected data is processed by the signal processing module, and the sensor-based modal analysis and noise filtering technology are introduced to obtain the dynamic response of the system more quickly, extract the modal parameters of the bridge structure, perform time-varying modal analysis, and identify the changes in modal parameters of the bridge structure under different loads and time;

[0013] The experimental data are visualized and analyzed to show the dynamic response characteristics of the bridge under different conditions. The health status and dynamic characteristics of the bridge structure are evaluated based on the changes in modal parameters, providing a reference for bridge design and maintenance.

[0014] In summary, when the bridge structure of the non-stationary vibration signal acquisition and analysis system of the linear time-varying structure simulating the car passing the bridge, the whole system shows significant time-varying characteristics, and the random vibration response signal of the bridge structure shows significant non-stationarity. Through the collected non-stationary vibration signal data, accurate linear time-varying structural modal analysis can be performed to identify the changes in modal parameters of the bridge structure under different car loads and time, so as to better understand its dynamic behavior. This has important reference value for bridge design and maintenance. The non-stationary vibration signal acquisition and analysis system of the linear time-varying structure simulating the car passing the bridge can simulate the dynamic characteristics under the condition of linear time-varying structure and can perform real-time acquisition and analysis of non-stationary vibration signals; the system can not only improve the dynamic monitoring and analysis capabilities of the bridge structure, but also provide strong technical support for the study of the dynamic characteristics of the linear time-varying structure, which has important practical significance and engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a device diagram of a non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a trolley crossing a bridge provided by an embodiment of the present invention;

[0016] Figure 2 3 is a diagram of a test and analysis system device for a non-stationary vibration signal acquisition and analysis system of a linear time-varying structure simulating a trolley crossing a bridge provided by an embodiment of the present invention;

[0017] Figure 3 It is a time domain diagram plotted by intercepting part of the data collected by the signal collected by the non-stationary vibration signal collection and analysis system of the linear time-varying structure simulating a trolley crossing a bridge provided by an embodiment of the present invention;

[0018] Figure 4 It is a spectrum diagram drawn according to the intercepted part of data provided by an embodiment of the present invention.

[0019] Figure 5 It is a flow chart of the experimental steps provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] refer to Figures 1 to 4 As shown, the first embodiment of the present invention discloses a non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge, which mainly includes: a time-varying structure (bridge and mobile mass block), an excitation system (exciter), a multi-modal sensor assembly, a measurement and analysis system, a motor system and a support platform. The two ends of the bridge are fixed to the top of the support platform, and the middle of the bridge is suspended; the mobile mass block is connected to the motor system through a steel plate and driven by the motor system to move along the bridge; the multi-modal sensor is vertically installed on the bottom of the bridge to collect vibration signals, and the data is processed by the measurement and analysis system. This system innovatively integrates a dynamic parameter control module, which can automatically adjust the movement mode (position, speed, acceleration) of the mass block according to the vibration signal collected in real time, and accurately simulate the driving process of different vehicles (such as large trucks, trains, small cars, etc.). In addition, the signal processing module can accurately perform time-frequency analysis and modal recognition on the collected non-stationary vibration signals by introducing a multi-modal sensor array (pressure, strain, acceleration) and advanced noise filtering and modal analysis technology.

[0022] Wherein, the time-varying structure is configured to simulate vehicles of different working conditions by changing the size of the moving mass block, and the motor system integrates a dynamic parameter adjustment function to control the movement mode of the moving mass block to realize a time-varying structure simulating different time-varying characteristics;

[0023] The measurement and analysis system is configured to implement the following steps by executing a computer program stored therein:

[0024] Acquire vibration signals of the bridge under different excitation conditions collected by the multimodal sensor assembly;

[0025] Process the collected data, extract the modal parameters of the bridge structure, conduct time-varying modal analysis, and identify the changes in modal parameters of the bridge structure under different loads and time;

[0026] During the experiment, the sampling frequency and time of the sensor are first set through the measurement and analysis system. The excitation system outputs an excitation signal of a specific frequency and applies external force to the bridge through the exciter. The mass block moves along the bridge under the control of the motor system, and the sensor collects the dynamic response data of the bridge in real time. After the data collection is completed, the signal processing module performs time-frequency analysis on the vibration data, extracts the modal parameters of the bridge, and displays the dynamic response characteristics of the bridge under different load conditions in real time.

[0027] The experimental data are visualized and analyzed to show the dynamic response characteristics of the bridge under different conditions. The health status and dynamic characteristics of the bridge structure are evaluated based on the changes in modal parameters, providing a reference for bridge design and maintenance.

[0028] In this embodiment, the time-varying structure includes a bridge (length, width and height in cm, 250×8×3) and a mobile mass block (10kg-30kg). By increasing or decreasing the mass size of the mass block, vehicles in different working conditions (large trucks, small trucks, trains, fully loaded trucks, empty trucks, cars, etc.), movement modes (position, speed and acceleration), etc. can be simulated to simulate time-varying structures with different time-varying characteristics. The dynamic parameter control module adjusts the various parameters of the mass block and the bridge in real time to more accurately simulate the driving process of different vehicles.

[0029] In this embodiment, the two ends of the bridge are fixed to the top of the bridge support platform to ensure that the middle of the bridge is suspended; the mobile mass block is installed so that it can move smoothly on the bridge surface; the exciter is placed on the ground, and the exciter top rod is in contact with the bridge support body; the multimodal sensor is placed vertically on the bottom of the bridge and connected to the measurement and analysis system; the motor system is fixed on the motor system support platform, and the mass block is driven to move by the reducer. Then data acquisition is performed: the sampling frequency and sampling time are preset by the measurement and analysis system; the excitation system outputs the excitation signal, and the exciter is transmitted to the bridge support body; the sensor collects the vibration signal of the bridge under different excitation conditions. Then data processing and analysis are performed: the collected data is processed by the measurement and analysis system to extract the modal parameters of the bridge structure; time-varying modal analysis is performed to identify the changes in the modal parameters of the bridge structure under different loads and times. Finally, the results are analyzed: the data is visualized and analyzed to show the dynamic response characteristics of the bridge under different conditions; according to the changes in the modal parameters, the health status and dynamic characteristics of the bridge structure are evaluated to provide a reference for bridge design and maintenance. The system has a compact structure and is easy to install and operate in an ordinary laboratory environment without the need for special sites and facilities. The device can be adjusted and configured according to experimental needs and is suitable for different types of experimental requirements.

[0030] Preferably, the motor system integrates a dynamic parameter adjustment function including a motor, a dynamic parameter adjustment module, an encoder, a motion controller and a reducer, the mobile mass block is connected to the reducer, the encoder and the motion controller are connected to the motor, the encoder and the motion controller are configured to control the motion form of the motor output end, the motor output end is fixedly connected to the reducer to drive the mass block to move on the bridge, the motor, the encoder and the motion controller form a closed loop, wherein the motion form of the motor output end includes position, speed and acceleration. The motor, the encoder and the motion controller are all uniformly placed in a chassis and fixed to the left side of the second platform, and the reducer is fixed to the top of the second platform. The system can dynamically adjust the motion trajectory, speed and acceleration of the trolley according to the real-time collected data. The dynamic parameter adjustment module is introduced, which can automatically adjust the motion speed and acceleration of the mass block according to the real-time collected vibration signal of the trolley when crossing the bridge, so as to ensure the simulation of the real dynamic response of the bridge under different working conditions.

[0031] In this embodiment, the motor system integrates the dynamic parameter adjustment function, including the motor, encoder, motion controller and Zhuolan planetary reducer. The encoder and motion controller are used to control the motion form (position, speed and acceleration) of the motor output end. The motor output end is directly connected to the reducer to drive the mass block to move on the bridge. The motor, encoder and motion controller form a closed loop, which can accurately control the motion form of the motor output end, and then realize the precise control of the motion form (position, speed and acceleration) of the mass block. In addition, the motor system can preset the motion information standard that the mass block needs to meet at the start of multi-modal sensor sampling. During the movement, when the motion information of the mass block meets the preset motion information standard, the measurement and analysis system starts the multi-modal sensor to start sampling, and the sampling end time is directly preset by the measurement and analysis system, which realizes the collection of excitation signals and structural dynamic response signals in any time period under any motion form of the mass block.

[0032] The motor, encoder and motion controller in the motor system are all installed in a chassis and fixed on the left side of the motor system support platform. The reducer is fixed on the top of the support platform and connected to the steel plate where the mass block is stored. The reducer drives the mass block to move on the bridge. The motor control module integrates the dynamic parameter adjustment function.

[0033] Specifically, this module includes:

[0034] Motion controller: Dynamically adjusts the acceleration and speed of the mass block based on the real-time collected bridge vibration signals. For example, when the system detects that the vibration amplitude of the bridge exceeds the set threshold, the motion controller will automatically reduce the movement speed of the mass block to prevent excessive vibration of the bridge;

[0035] Feedback control mechanism: The system can automatically adjust the position and speed of the mass block based on real-time feedback from vibration data, making the simulated car crossing the bridge process closer to the actual working conditions. Through this function, the system can cope with the dynamic response under different bridge structures and vehicle conditions, and achieve more accurate experimental simulation.

[0036] Specifically, in this embodiment, the motor system drives the mass block to move on the bridge. It controls the speed, distance, acceleration, number of back and forth movements, etc. through a reducer. These are mainly controlled by the encoder and motion controller in its chassis. They and the motor are installed in a chassis and fixed on the left side of the motor system support platform. The reducer is fixed on the top of the support platform and is connected to the steel plate where the mass block is stored to drive the mass block to move on the bridge.

[0037] Preferably, both ends of the bridge are fixed to the top of the first platform by screws and stainless steel plates, the middle part of the bridge is in a suspended state, and two smooth grooves are provided on the top of the bridge so that the movable mass block can move smoothly on the bridge deck.

[0038] Based on a real-time feedback control mechanism, the system can automatically adjust the excitation signal of the excitation system and the motion trajectory of the mass block according to the bridge vibration signal collected by the sensor. When the bridge vibration amplitude is detected to exceed the set threshold, the system will automatically reduce the speed of the mass block to avoid excessive vibration of the bridge structure and ensure the accuracy of the experimental data.

[0039] In order to improve the accuracy of the experiment, this system introduces a real-time feedback control mechanism. This mechanism can dynamically adjust the excitation signal of the excitation system and the motion mode of the mass block according to the real-time vibration signal collected by the sensor. The specific operations are as follows:

[0040] Dynamic adjustment of the excitation system: When the bridge vibration signal exceeds the set threshold, the system will control the output signal of the excitation system through a computer, automatically adjust the excitation amplitude and frequency, and ensure that the bridge remains within a safe vibration range during the experiment.

[0041] Adaptive adjustment of motion mode: Through real-time acquisition of bridge vibration data, the system can adjust the motion trajectory of the mass block according to the actual response of the bridge. When the bridge is detected to be vibrating violently, the system will automatically reduce the speed of the mass block; when the vibration amplitude decreases, the system will gradually increase the speed of the car to achieve a more realistic experimental simulation.

[0042] In this embodiment, it should be noted that the bridge and the supporting platform are not directly connected, but two stainless steel plates (25×5×5) are placed on the top of the supporting platform, and the two ends of the bridge are placed on the steel plates and then fixed with screws.

[0043] Preferably, the movable mass block is composed of a mass block, a stainless steel plate, four cylindrical steel columns, and two smooth spheres. Four holes are opened on the mass block. The four cylindrical steel columns are placed on the stainless steel plate. The mass block passes through the four cylindrical steel columns and is movably placed on the stainless steel plate. The first lower end surface of the stainless steel plate is connected to the spheres to simulate the movement of a trolley wheel on the bridge. The second lower end surface of the stainless steel plate is connected to the reducer in the motor system.

[0044] In this embodiment, the movable mass block is composed of a stainless steel plate (40×20×1), four cylindrical steel columns, and two smooth spheres. The mass block is placed on the steel plate, and a section below the steel plate is connected to the smooth spheres to simulate the movement of a trolley wheel on a bridge. The four holes of the mass block are lowered facing the cylindrical steel columns to fix the mass block, and the other end below the steel plate is connected to the reducer in the motor system.

[0045] Preferably, the excitation system includes an exciter and a power amplifier, the exciter is connected to the power amplifier, the exciter is configured to output different types of bandwidth signals or single-frequency signals, the power amplifier is configured to adjust the amplitude of the output signal, the exciter adopts a DH40200 exciter, and the power amplifier adopts a DH5872 power amplifier.

[0046] In this embodiment, the vibration exciter top rod cannot be too close to the support platform, and a distance of about 1 cm should be reserved to prevent the vibration exciter from burning out due to long-term inability to vibrate.

[0047] Preferably, on the basis of existing displacement and acceleration sensors, pressure sensors, strain sensors and temperature sensors are added. This system uses multimodal sensors, including pressure sensors, strain sensors and acceleration sensors, which are used to monitor the pressure, stress and acceleration response of the bridge structure during the process of the trolley crossing the bridge. The data of these sensors are processed and visualized in real time through the measurement and analysis system to ensure that the dynamic characteristics of the bridge are accurately captured under different working conditions.

[0048] In this embodiment, a multimodal sensor is selected to measure the excitation signal of the time-varying structure; a multimodal sensor is selected to measure the dynamic response signal of the structure under the excitation, and the sensor is placed on the bottom of the bridge in a manner perpendicular to the bottom of the bridge. The sensor is an IEPE sensor connected to the BNC (Q9) line through the IEPE signal input line, and then connected to the data acquisition channel in the DH5922N dynamic signal test and analysis system.

[0049] Preferably, the measurement and analysis system adopts a DH5922N dynamic signal test system, and the measurement and analysis system is configured to preset the sampling frequency and sampling time of the multimodal sensor assembly, and analyze and process the excitation signal and structural dynamic response signal collected by the multimodal sensor assembly.

[0050] This system uses advanced data processing algorithms to perform time-frequency analysis and modal identification on the vibration signals collected by the sensor. The specific steps are as follows:

[0051] Time-frequency analysis: The vibration signal of the bridge is processed using wavelet transform and Hilbert-Huang transform, which can simultaneously analyze the time domain and frequency domain information of the signal and identify the dynamic response characteristics of the bridge under different loads and time.

[0052] Modal Identification: The system extracts the modal parameters of the bridge (including natural frequency, damping ratio and vibration mode) and analyzes the modal changes of the bridge structure in real time when the car passes over the bridge. The modal identification process can identify the key modal parameters of the bridge under different loads and provide accurate health assessment data.

[0053] In this embodiment, the DH5922N dynamic signal test and analysis system of Donghua Testing is used, which can be used to preset the sampling frequency and sampling time of the multi-modal sensor, and process the excitation signal and structural dynamic response signal collected by the sensor. The measurement and analysis system uses time-frequency analysis tools (such as wavelet transform and Hilbert-Huang transform) to process the collected vibration signals, and extracts the modal parameters of the bridge under different trolley loads through the time-varying modal recognition algorithm, analyzes the changes in the dynamic characteristics of the bridge in real time, and provides a reference for bridge health assessment. .

[0054] Preferably, the first platform and the second platform are constructed of metal profiles, the size of the first platform is 250cm×77cm×104cm, wherein the width of the top beam, the side columns and the bottom beam are all 10cm, and the size of the second platform is 250cm×40cm×104cm, wherein the width of the top beam, the side columns and the bottom beam are all 5cm.

[0055] In this embodiment, the two support platforms are not connected, and their specifications and sizes are different, but their heights are parallel. The two support platforms are connected by a steel plate for storing mass blocks. The reason for using two support platforms instead of the same support platform is that the motor system will inevitably generate some vibrations when working, and these vibrations will cause the vibration signals collected when the car crosses the bridge to be inaccurate, so the motor system is separated from the bridge in order to measure more accurate vibration signal data. In short, the bridge support platform and the motor system support platform, as the name implies, one supports the bridge and the other supports the motor system. The bridge is fixed to the top of the support platform by padding with two stainless steel blocks of size (25×5×5). The motor system support platform is not directly connected to the bridge support platform, but is highly parallel to ensure that the influence of the motor system vibration on the bridge vibration signal is reduced in the experiment.

[0056] Specifically, in this embodiment, the non-stationary vibration signal acquisition and analysis system of the linear time-varying structure simulating a trolley crossing a bridge first simulates an actual bridge structure. The two ends of the bridge are fixed to the top of the platform supporting the bridge by screws. The middle of the bridge is in a suspended state. A stainless steel plate is placed on the bridge. The number of steel blocks (i.e., mass) on the plate can be increased or decreased as needed. The steel plate is connected to the reducer of the motor system to change the movement mode (position, velocity and acceleration) of the mass block to simulate time-varying structures with different time-varying characteristics.

[0057] After determining the size of the mass block, place the exciter of the excitation system on the ground, point the top rod of the exciter to a certain position of the bridge support platform, and connect the exciter to the power amplifier, which is then connected to the DH5922N dynamic signal test and analysis system. The exciter is used to output different types of bandwidth signals or single-frequency signals, and the power amplifier is used to adjust the amplitude of the output signal.

[0058] In summary, the bridge structure of the non-stationary vibration signal acquisition and analysis system of the linear time-varying structure simulating a car passing over the bridge shows significant time-varying characteristics when the car passes, and the random vibration response signal of the bridge structure shows significant non-stationarity. Through the collected non-stationary vibration signal data, accurate linear time-varying structural modal analysis can be performed to identify the changes in modal parameters of the bridge structure under different car loads and time, so as to better understand its dynamic behavior. It aims to solve the problems that traditional experimental equipment cannot accurately simulate the linear time-varying structure of a car passing over the bridge and capture certain changes in its non-stationary vibration signal in real time, and improve the dynamic monitoring and analysis capabilities of the bridge structure.

[0059] Experimental process:

[0060] 1. Experimental preparation stage: First, fix both ends of the bridge on the supporting platform and ensure that the middle of the bridge is suspended. Install and calibrate the multimodal sensor and adjust its sampling frequency to 1000Hz. Connect the excitation system and set the initial excitation signal frequency to 1Hz to 100Hz to ensure that the experimental excitation signal can cover the possible response frequency of the bridge.

[0061] 2. Data sampling phase: Start the measurement and analysis system and begin collecting vibration signals of the bridge under excitation conditions. The multimodal sensor will simultaneously collect data such as pressure, strain, acceleration, etc. of the bridge to ensure that the dynamic response of the bridge can be captured in multiple dimensions. The system dynamically adjusts the sampling frequency according to the vibration characteristics of the bridge to avoid data redundancy or information loss.

[0062] 3. Dynamic adjustment and feedback stage: During the data collection process, the system automatically monitors the vibration amplitude of the bridge through a real-time feedback mechanism. If the vibration amplitude is detected to exceed the safety threshold of 5mm, the system will automatically reduce the excitation amplitude of the exciter and slow down the movement speed of the mass block to prevent excessive vibration of the bridge and ensure the safety and effectiveness of the experimental process.

[0063] 4. Data processing stage: The collected data will be analyzed through wavelet transform and Hilbert-Huang transform to identify the modal parameters such as the natural frequency and damping ratio of the bridge. According to different load conditions, the system updates the analysis results in real time to ensure efficient and accurate data processing during the experiment.

[0064] 5. Result visualization and analysis stage: Finally, the experimental results will be visualized through the measurement and analysis system to generate the dynamic response curve of the bridge under different excitation conditions. By analyzing the changes in modal parameters, the health status of the bridge can be evaluated to determine whether there is structural damage or fatigue, providing a scientific basis for bridge maintenance.

[0065] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge, characterized in that: include: A time-varying structure, an excitation system, a multimodal sensor assembly, a measurement and analysis system, a motor system and a support platform, a dynamic parameter control module, and a signal processing module. The time-varying structure includes a bridge and a moving mass block. The excitation system is configured on the ground. The exciter top rod of the excitation system contacts the support body of the bridge. The multimodal sensor assembly is vertically placed on the bottom surface of the bridge. The support platform is placed on the horizontal ground. The support platform includes a first platform and a second platform. The first platform is used to support the bridge, and the second platform is used to support the motor system. The two ends of the bridge are fixed to the first and last ends of the top of the first platform. The moving mass block is connected to the motor system through a steel plate. The motor system is installed on the left and top of the second platform. The multimodal sensor assembly is vertically placed on the bottom surface of the bridge. The support platform is placed on the horizontal ground. The support platform includes a first platform and a second platform. The first platform is used to support the bridge, and the second platform is used to support the motor system. The two ends of the bridge are fixed to the first and last ends of the top of the first platform. The moving mass block is connected to the motor system through a steel plate. The motor system is installed on the left and top of the second platform. The sensor components include not only force sensors, strain sensors and motion sensors, but also pressure sensors and temperature sensors. They can capture complex non-stationary vibration signals of bridge structures in real time under a wider range of environments and working conditions, and provide richer and more accurate data than a single sensor. The dynamic parameter control module is combined with a real-time feedback control system, which can dynamically adjust the load, excitation signal and motion parameters (position, speed, acceleration) of the bridge and the trolley (mass block) to ensure that the non-stationary characteristics of the simulated bridge structure under different conditions have higher accuracy and sensitivity. The signal processing module can extract the precise modal parameters of the bridge structure from the non-stationary signals collected by multi-modal sensors by combining advanced time-frequency analysis techniques such as wavelet transform and Hilbert-Huang transform. Compared with the existing single signal processing technology, this module significantly improves the analysis accuracy and response speed of non-stationary vibration signals; The time-varying structure is configured to simulate vehicles of different working conditions by changing the size of the moving mass block, and the motor system integrates a dynamic parameter adjustment function to control the movement mode of the moving mass block to realize a time-varying structure simulating different time-varying characteristics; the time-varying characteristics of the structure simulated in the prior art are only achieved by changing the speed and position of the mass block, and the system in the present invention can further improve the simulation accuracy of the non-stationarity of the structure by adjusting the bridge load and the acceleration of the trolley (mass block) in real time; The measurement and analysis system is configured to implement the following steps by executing a computer program stored therein: Acquire vibration signals of the bridge under different excitation conditions collected by the multimodal sensor assembly; The collected data is processed to extract the modal parameters of the bridge structure, and time-varying modal analysis is performed to identify the changes in the modal parameters of the bridge structure under different loads and time. A real-time feedback control mechanism is added based on the existing technology. Based on the collected vibration signal, the excitation signal of the excitation system or the motion mode of the mass block is automatically adjusted, so that the simulated car crossing the bridge process is closer to the actual working condition. The experimental data are visualized and analyzed to show the dynamic response characteristics of the bridge under different conditions. The health status and dynamic characteristics of the bridge structure are evaluated based on the changes in modal parameters, providing a reference for bridge design and maintenance.

2. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The motor system integrates a dynamic parameter adjustment function and includes a motor, an encoder, a motion controller and a reducer. The movable mass block is connected to the reducer, and the encoder and the motion controller are connected to the motor. The encoder and the motion controller are configured to control the motion form of the motor output end. The motor output end is fixedly connected to the reducer to drive the mass block to move on the bridge. The motor, the encoder and the motion controller form a closed loop, wherein the motion form of the motor output end includes position, speed and acceleration.

3. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 2 is characterized in that: The motor, encoder and motion controller are all placed in a chassis and fixed on the left side of the second platform, and the reducer is fixed on the top of the second platform.

4. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The bridge is fixed by stainless steel plates to ensure structural stability under different load and motion conditions. The suspended design of the bridge cooperates with the dynamic movement of the mass block so that the non-stationary vibration signal of the bridge structure can be captured more accurately. Two smooth grooves are provided on the top of the bridge to enable the moving mass block to move smoothly on the bridge deck.

5. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The movable mass block consists of a mass block, a stainless steel plate, four cylindrical steel columns, and two smooth spheres. Four holes are opened on the mass block. The four cylindrical steel columns are placed on the stainless steel plate. The mass block passes through the four cylindrical steel columns and is movably placed on the stainless steel plate. The first lower end surface of the stainless steel plate is connected to the spheres to simulate the movement of a trolley wheel on the bridge. The second lower end surface of the stainless steel plate is connected to the reducer in the motor system.

6. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The excitation system includes an exciter and a power amplifier, the exciter is connected to the power amplifier, the exciter is configured to output different types of bandwidth signals or single-frequency signals, the power amplifier is configured to adjust the amplitude of the output signal, the exciter adopts a DH40200 exciter, and the power amplifier adopts a DH5872 power amplifier.

7. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The multimodal sensor assembly includes a pressure sensor, a strain sensor and a motion sensor. The force sensor is configured to measure the excitation signal received by the time-varying structure, and the motion sensor is configured to measure the dynamic response signal of the structure under the excitation. The force sensor adopts a mechanical impedance sensor, and the motion sensor adopts an acceleration sensor. Most existing systems adopt a single type of sensor (such as a displacement or acceleration sensor), and the system proposed in the present invention can be combined with multimodal sensors, including pressure sensors, strain sensors and temperature sensors, to perform real-time monitoring in more dimensions.

8. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The measurement and analysis system adopts the DH5922N dynamic signal test system. The measurement and analysis system is configured to preset the sampling frequency and sampling time of the multimodal sensor assembly, and analyze and process the excitation signal and structural dynamic response signal collected by the multimodal sensor assembly. The system adds spectrum analysis and time-frequency analysis tools, and uses more advanced frequency analysis methods (such as wavelet transform and Hilbert-Huang transform) to further extract non-stationary features in bridge vibration.

9. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1 is characterized in that: The first platform and the second platform are constructed of metal profiles. The size of the first platform is 250cm×77cm×104cm, wherein the width of the top beam, the side columns and the bottom beam are all 10cm. The size of the second platform is 250cm×40cm×104cm, wherein the width of the top beam, the side columns and the bottom beam are all 5cm.

10. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1, characterized in that: The non-stationary vibration signal acquisition and analysis system of the linear time-varying structure simulating a car crossing a bridge can be applied to various bridge structures, such as highway bridges, railway bridges, and cable-stayed bridges. The system can flexibly adjust the modal parameters of the bridge according to different bridge structures, so that the system can provide accurate vibration signal acquisition and analysis when dealing with different vehicle working conditions such as large trucks, trains, fully loaded vehicles and empty vehicles, ensuring that the system can adapt to complex working conditions.

11. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1, characterized in that: The system can simulate the vehicle driving process under different load conditions, including the dynamic response of fully loaded and unloaded trucks, by adjusting the mass and motion form of the moving mass. This design ensures that the system can accurately reflect the dynamic impact of different vehicles on the bridge structure during bridge inspection and evaluation, providing reliable data support for bridge health monitoring and maintenance.

12. The non-stationary vibration signal acquisition and analysis system for a linear time-varying structure simulating a car crossing a bridge according to claim 1, characterized in that: The system is not only applicable to steel structure bridges, but also to concrete bridges and composite bridges. By adjusting the dynamic parameter control module and the settings of the multimodal sensor, the system can cope with bridges of different sizes, materials and structural forms, and collect high-precision vibration signals under actual working conditions to ensure the safety assessment of the bridge structure under different load and vibration conditions.

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