A high-speed train shock absorber test system and method

Abstract

A high-speed train shock absorber test system and method, belonging to the field of train test simulation technology. The present invention can solve the problems of high cost and long cycle of whole vehicle testing, inability to achieve extreme working conditions, and inability to consider coupling effects in performance testing. The system of the present invention includes a loading system that drives an actuator to enable the shock absorber to achieve dynamic command displacement, a data acquisition system for collecting the actual displacement and reaction force of the shock absorber, a real-time simulation calculation system for real-time calculation of numerical model response, completion of dynamic characteristic compensation, sending loading system commands, and online monitoring of test stability, and a data interaction system for realizing communication between the real-time simulation calculation system and the loading system. In the process of completing the dynamic characteristic compensation, it is determined whether dynamic characteristic compensation is required based on the dynamic characteristics of the test shock absorber, and the loading error generated by the loading system is reduced by the dynamic characteristic compensation method, thereby obtaining the command displacement of the test shock absorber.

Description

Technical Field

[0001] The invention belongs to the technical field of train test simulation, and in particular relates to a high-speed train shock absorber test method. Background Art

[0002] In recent years, China's high-speed trains have entered a period of rapid development and have achieved many breakthroughs. They are widely praised for their safe and stable operation. However, with the occurrence and development of factors that affect train performance, such as wheel-rail wear, roadbed settlement and device aging, the operation performance of high-speed trains will gradually deteriorate. How to maintain good running stability has become an urgent problem to be solved. The lateral and serpentine vibrations in the operation of high-speed trains will not only aggravate wheel-rail wear and affect the stability of train operation, but also reduce the safety of train operation and increase the risk of train derailment. At the same time, high-speed trains often run on bridges, and vehicle-bridge coupling vibrations will occur between high-speed trains and bridges. The dynamic pressure of the wind and the high-speed running trains produce dynamic effects on the bridge, and the bridge will produce corresponding vibration responses, which further excite the vibration of the train. Therefore, the vehicle-bridge coupling vibration will have a great impact on the stability and comfort of the train. Installing shock absorbers is an effective measure to suppress undesirable vibrations of trains, which can improve the critical speed of train instability, running comfort and system life. Studying the stress state of the shock absorber during train operation and the dynamic coupling relationship between the shock absorber and the car body is of great value for further improving the train's running speed, running stability and safety.

[0003] At present, the testing methods of high-speed train shock absorbers can be mainly divided into two types: one is to use a vibration test bench to test the entire train or the underframe of the train; the other is to use a shock absorber test machine to test the performance of the shock absorber. Although the former can reproduce the coupling effect between the shock absorber and the entire train or the underframe of the train, it is not suitable for shock absorber research and testing work that requires a large number of tests due to the high testing cost. The latter usually uses an actuator and only performs a specific load test on the shock absorber. Although the testing cost is relatively low, it cannot consider the coupling effect between the shock absorber and the rest of the train, and it is difficult to accurately evaluate the impact of the shock absorber on the dynamic behavior of the train. In view of this, the present invention provides a high-speed train shock absorber test system and method, which can make up for such deficiencies and has outstanding advantages and broad application prospects. Summary of the invention

[0004] In order to solve the problems of high cost and long cycle of whole vehicle testing, inability to achieve extreme working conditions, and inability to consider coupling effects in performance testing, the present invention proposes a high-speed train shock absorber testing system and method in response to the shock absorber test evaluation needs.

[0005] A high-speed train shock absorber test system, comprising:

[0006] A real-time simulation calculation system is used to calculate the response of the numerical model in real time, and to determine whether dynamic characteristic compensation is required according to the dynamic characteristics of the test shock absorber. If dynamic characteristic compensation is not required, the predicted displacement of the test shock absorber is directly used as the command displacement; otherwise, the loading error generated by the loading system is reduced according to the predicted displacement of the test shock absorber through the dynamic characteristic compensation method, thereby obtaining the command displacement of the test shock absorber;

[0007] The loading system drives the actuator to achieve dynamic command displacement of the shock absorber;

[0008] Data acquisition system, used to collect the actual displacement and reaction force of the shock absorber;

[0009] The data interaction system is used to realize the communication between the real-time simulation computing system and the loading system, such as sending the reaction force of the shock absorber to the real-time simulation computing system.

[0010] A high-speed train shock absorber test method comprises the following steps:

[0011] S1. Dividing a test object system including a shock absorber into a physical specimen part and a numerical model part; the test object system is a test object system including a high-speed train;

[0012] The physical specimen is a shock absorber, which is recorded as the test shock absorber; the numerical model is a numerical model corresponding to the remaining parts of the test object system except the shock absorber, which is recorded as the object numerical model;

[0013] S2, installing the test shock absorber on the test bench to prepare for loading, compiling and downloading the numerical model to the real-time control board corresponding to the real-time simulation computing system, and establishing communication between the loading system and the real-time simulation computing system;

[0014] S3, assuming that the reaction force of the test shock absorber is zero when i=1, based on the object numerical model, the predicted displacement of the interface between the object numerical model and the test shock absorber in the next step is calculated according to the load action in the object numerical model, and the predicted displacement at time i is stored in the memory;

[0015] S4. judging whether dynamic characteristic compensation is required according to the dynamic characteristic of the test shock absorber; if dynamic characteristic compensation is not required, directly taking the predicted displacement of the test shock absorber as the command displacement; otherwise, according to the predicted displacement of the test shock absorber, using the dynamic characteristic compensation method to reduce the loading error generated by the loading system, thereby obtaining the command displacement of the test shock absorber; and using a memory to store the command displacement at this moment;

[0016] S5, the command displacement of the test shock absorber is transmitted by the data interaction system, the command displacement of the test shock absorber is used as the target displacement, and the target displacement is sent to the loading system as a control signal through the real-time simulation calculation system to drive the hydraulic servo actuator to physically load the test shock absorber;

[0017] S6. The measured displacement and measured reaction force of the test shock absorber are measured by the displacement sensor and the force sensor, the measured reaction force of the test shock absorber is collected by the data acquisition system, and then the measured reaction force is fed back to the object numerical model through the real-time simulation calculation system based on the data interaction system; based on the object numerical model, the motion response of the corresponding object system is calculated according to the measured reaction force of the test shock absorber and the load action of the i+1th step in the object numerical model, and the predicted displacement of the interface between the object numerical model and the test shock absorber in the next step is determined according to the motion response, and the predicted displacement at this moment is stored in the memory to complete data transmission and update;

[0018] S7. Let i=i+1, and repeat S4 to S6 until the test is finished.

[0019] Further, in the process of feeding back the measured reaction force to the object numerical model through the real-time simulation calculation system based on the data interaction system in S6, the measured reaction force is replaced by the measured reaction force correction value, and then the measured reaction force correction value is fed back to the object numerical model;

[0020] The calculation formula of the measured reaction force correction value is as follows:

[0021]

[0022] in, f e,i are the measured reaction force correction value and the measured reaction force of the shock absorber in the i-th step test respectively; c e is the damping of the test shock absorber; k e is the stiffness of the test shock absorber; x i 、x e,i , and are the predicted displacement, actual displacement, predicted speed and measured speed of the shock absorber in the i-th test respectively.

[0023] Furthermore, the method also includes the step of online real-time monitoring of test stability, that is, for the S3-S7 test process, an energy-based online monitoring index of test stability is used to monitor the test stability online in real time.

[0024] Furthermore, the energy-based online monitoring indicators of test stability are as follows:

[0025] E i =E n +E p

[0026]

[0027]

[0028] Among them, E i The energy dissipated by the entire system is an indicator for evaluating the stability of the system; E n is the energy dissipated by the object numerical model, is the trapezoidal integral of the work done by the damping force of the object numerical model on the predicted displacement, and is the hysteresis energy dissipated by the object numerical model; E p is the energy dissipated by the equivalent specimen, obtained by the trapezoidal integration of the work done by the measured reaction force on the predicted displacement. The equivalent specimen is a virtual specimen whose mechanical properties satisfy the measured force-predicted displacement relationship; f n,i is the damping force of the numerical model part of the object in step i; f e,i is the measured reaction force of the shock absorber part in the i-th step test; x i and q are the predicted displacement of the i-th step and the total number of test steps, respectively.

[0029] Furthermore, in the process of online real-time monitoring of test stability using energy-based test stability online monitoring indicators, if the monitoring indicator E i is positive, then the system response will be bounded and the system is stable; if the monitoring indicator E i If it is negative, the response of the system will be unbounded and the test will be unstable, then the test will be terminated directly.

[0030] Furthermore, in the process of determining whether dynamic characteristic compensation is required according to the dynamic characteristics of the test shock absorber in S4, the time axis error damping ratio ψ c As a prediction index for dynamic characteristic compensation, if the prediction index ψ c ≤[ψ c ], where [ψ c ] is the allowable time axis error damping ratio, then there is no need to perform dynamic characteristic compensation, otherwise it is necessary to perform dynamic characteristic compensation;

[0031] The time axis error damping ratio is as follows:

[0032]

[0033] Among them, τ is the time error corresponding to the phase error, and ω is the system's serpentine vibration circular frequency.

[0034] Furthermore, when dynamic characteristic compensation is required, a nonlinear least squares extrapolation compensation method is used as the dynamic characteristic compensation method.

[0035] Furthermore, the object system is a high-speed train system; the object numerical model is a vehicle body numerical model;

[0036] The numerical model of the car body is expressed in the form of motion equations. The motion equations of high-speed trains are as follows:

[0037]

[0038] Where M, C and K are the mass, damping and stiffness matrices of the train system respectively; X is the displacement vector of each degree of freedom, is the first derivative of X, is the second-order derivative of X; u is the damping force vector generated by the test shock absorber; w is the linear or nonlinear wheel-rail contact force, which is related to the wheel-rail model, track irregularity, etc.; l u and l w is the coefficient matrix, which is related to the test shock absorber installation and track irregularity, etc.; F is the wind load vector borne by the train at high speed;

[0039] S6 is a process of calculating the motion response of the corresponding object system based on the measured reaction force of the test shock absorber and the i+1-step load action in the object numerical model, that is, a process of calculating the corresponding vehicle body motion response based on the measured reaction force of the test shock absorber and the i+1-step track unevenness action and wind load excitation in the vehicle body numerical model.

[0040] Alternatively, the object system is a train-bridge coupling system; the object numerical model is a train-bridge coupling system numerical model;

[0041] The train-bridge coupling system is composed of a high-speed train subsystem and a bridge subsystem, and its motion equation is as follows:

[0042]

[0043] Among them, M v , C v are the mass and damping of the train subsystem; M b , C b are the total mass and total damping matrix of the bridge subsystem; K system =K1+K2 is the overall stiffness matrix of the system, where K1 is the overall stiffness matrix of the vehicle subsystem and the bridge subsystem without considering the coupling term; K2 is the contact matrix between the vehicle and the track; F v and F b are the external force load vectors of the train subsystem and the bridge subsystem respectively; X v , and X b , are the displacement, velocity, and acceleration vectors of the train subsystem and the bridge subsystem, respectively; R is the measured reaction force vector of the test shock absorber;

[0044] S6 is the process of calculating the motion response of the corresponding object system based on the measured reaction force of the test shock absorber and the i+1-step load action in the object numerical model, that is, the process of calculating the motion response of the corresponding train-bridge coupling system based on the measured reaction force of the test shock absorber and the i+1-step load excitation.

[0045] The beneficial effects of the present invention are:

[0046] The present invention proposes a high-speed train shock absorber test system and method, which synchronously carry out the physical loading of the real shock absorber and the solution of the train numerical model (which may include bridge model, wind field model, earthquake model, etc. as needed), and the two interact with each other in real time, which can accurately reproduce the force process of the shock absorber and the coupling effect between the shock absorber and the train; only the shock absorber is used as the actual test piece, which greatly saves the test cost and test cycle compared with the whole vehicle test; the numerical method is used to simulate the rest of the train, which reduces the requirements for the test equipment; the parameters can be adjusted to simulate the train dynamic behavior under different working conditions, thereby improving the test efficiency and the test detection capability of extreme working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] For the convenience of explanation, the present invention is described in detail with reference to the following specific embodiments and the accompanying drawings.

[0048] Figure 1 This is a flow chart of the test method for the high-speed train shock absorber test system;

[0049] Figure 2 It is a schematic diagram of the test method principle of the high-speed train shock absorber test system;

[0050] Figure 3 The flowchart of the test method is a test of the shock absorber of the vehicle-bridge coupling system as an example;

[0051] Figure 4 Schematic diagram of the test method principle, taking the vehicle-bridge coupling system shock absorber test as an example. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is described below by specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. It should be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and processing steps closely related to the present invention are shown in the accompanying drawings, and other details that are not very relevant are omitted.

[0053] The high-speed train shock absorber test method of the present invention needs to be implemented with the help of a high-speed train shock absorber test system, and the high-speed train shock absorber test system includes a real-time simulation calculation system, a loading system, a data acquisition system, a data interaction system, etc.

[0054] The real-time simulation calculation system is used to calculate the response of the numerical model in real time, complete the dynamic characteristic compensation, and send the loading system command; the process of completing the dynamic characteristic compensation: judging whether the dynamic characteristic compensation is required according to the dynamic characteristic of the test shock absorber, if the dynamic characteristic compensation is not required, directly taking the predicted displacement of the test shock absorber as the command displacement; otherwise, according to the predicted displacement of the test shock absorber, the dynamic characteristic compensation method is used to reduce the loading error generated by the loading system, thereby obtaining the command displacement of the test shock absorber;

[0055] The loading system drives the actuator to achieve dynamic command displacement of the shock absorber;

[0056] Data acquisition system, used to collect the actual displacement and reaction force of the shock absorber;

[0057] The data interaction system is used to realize the communication between the real-time simulation computing system and the loading system, such as sending the reaction force of the shock absorber to the real-time simulation computing system.

[0058] The high-speed train shock absorber test method described in the present invention simulates the main parts of the power system such as the train, shock absorber, bridge, earthquake, wind, etc. through simulation technology, simulates a single key shock absorber through physical experiments, and conducts experiments on the test system to evaluate the dynamic performance of the shock absorber and its coupling with the surrounding environment in a low-cost, efficient and accurate manner.

[0059] In order to fully illustrate the present invention, a high-speed train shock absorber test method is described in more detail through a specific implementation method.

[0060] Specific implementation method 1: Combination Figure 1 , Figure 2 To explain this embodiment,

[0061] This embodiment is a high-speed train shock absorber test method provided by the present invention.

[0062] A high-speed train shock absorber test method specifically comprises the following steps:

[0063] S1. Divide the high-speed train into a physical specimen part and a numerical model part; the physical specimen is a shock absorber of the high-speed train, recorded as a test shock absorber; the numerical model is a numerical model corresponding to the remaining car body except the shock absorber, which can be established using MATLAB / Simulink and recorded as a car body numerical model.

[0064] The numerical model of the vehicle body is expressed in the form of motion equations, and its parameters include vehicle body mass and moment of inertia, structure mass and moment of inertia, wheelset mass and moment of inertia, primary and secondary spring stiffness and shock absorber damping coefficients, vehicle dimensions, wheel-rail contact model parameters, track irregularity information, etc. It can also include train running speed, bridge model, train-air coupling model, etc., and more factors can be considered according to actual conditions. The motion equation of a high-speed train can be expressed as

[0065]

[0066] Where M, C and K are the mass, damping and stiffness matrices of the train system respectively; X is the displacement vector of each degree of freedom, is the first derivative of X, is the second-order derivative of X; u is the damping force vector generated by the test shock absorber; w is the linear or nonlinear wheel-rail contact force, which is related to the wheel-rail model, track irregularity, etc.; l u and l w is the coefficient matrix, which is related to the test shock absorber installation and track irregularity, etc.; F is the wind load vector borne by the train when running at high speed.

[0067] The parameters of the vehicle body numerical model at the i-th moment are stored in the memory and transmitted by the data interaction system to the vehicle body numerical model motion equation in the real-time simulation calculation system to calculate the predicted displacement at the i+1 moment in real time.

[0068] S2. Install the test shock absorber on the test bench to prepare for loading, compile the vehicle body numerical model using C language, download it to the real-time control board corresponding to the real-time simulation computing system, and establish communication between the loading system and the real-time simulation computing system.

[0069] The loading system adopts an electro-hydraulic servo loading system (such as MTS test system, Fuyun Tianyi loading system, Zhongji test loading system, etc.), including: a host computer, a controller, a hydraulic servo actuator, etc.

[0070] The real-time simulation computing system includes but is not limited to a DSpace system, an xPC target machine, an industrial computer, a NI controller system, and the like.

[0071] S3, assuming that the reaction force of the test shock absorber is zero when i=1, based on the vehicle body numerical model, according to the track irregularity and wind load excitation at this moment in the vehicle body numerical model, calculate the predicted displacement of the interface between the vehicle body numerical model and the test shock absorber in the next step, and use a memory to store the predicted displacement at moment i;

[0072] The track unevenness is processed into track unevenness in the time domain using track power spectrum density. The single-sided power spectrum density function of track unevenness is converted into a double-sided function and processed by discretization sampling; the spectrum of track unevenness is calculated based on the discretization sampling result, and the fast Fourier inverse transform is performed to obtain the time series of track unevenness. The time series information of track unevenness is reflected by w of the motion equation. According to the track unevenness effect, wind load excitation and measured reaction force of the test shock absorber in the i-th step transmitted to the vehicle body numerical model, the numerical model motion equation calculates the predicted displacement of the interface between the vehicle body numerical model and the test shock absorber in real time.

[0073] S4, based on dynamic characteristics compensation prediction index ψ c , to pre-judge whether dynamic characteristic compensation is needed. If the prediction index prediction index ψ c ≤[ψ c ], where [ψ c ] is the allowable time axis error damping ratio, the influence of the loading error can be ignored, and there is no need to perform dynamic characteristic compensation. The predicted displacement of the test shock absorber is directly used as the command displacement to simplify the test process; otherwise, the loading error (phase error and amplitude error) generated by the loading system is reduced by the dynamic characteristic compensation method according to the predicted displacement of the test shock absorber, so that the command displacement of the test shock absorber can be obtained, and the memory is used to store the command displacement at this moment;

[0074] In order to pre-judge whether the test method of the present invention needs to be compensated for dynamic characteristics in order to obtain reasonable test results, the present invention analyzes the influence of loading error on the test method of the present invention, thereby proposing a dynamic characteristics compensation prediction index. In order to more clearly describe the dynamic characteristics compensation prediction index, only the motion equation of a single degree of freedom system including a test shock absorber is used for derivation. The single degree of freedom system including the test shock absorber is the snaking vibration mode of the high-speed train power system. The derivation process is as follows:

[0075] The equation of motion of the single degree of freedom system including the test shock absorber is:

[0076]

[0077] in, ξ=c e / (2·m·ω); m and k are the mass and stiffness of the system respectively; x, and f are the displacement, acceleration and external force of the system respectively; ω and ξ are the system's serpentine vibration circular frequency and the damping ratio of the test shock absorber respectively; t represents time; c e is the damping of the test shock absorber, It represents the first-order derivative of the displacement of the test shock absorber, that is, the actual velocity of the test shock absorber. It should be noted that the displacement x and velocity of the system and acceleration These are the predicted displacement, velocity and acceleration of the test shock absorber.

[0078] Due to the loading error, the actual speed of the test shock absorber at time t With prediction speed Different. Using the actuator model that considers amplitude error and phase error, we have

[0079]

[0080] Among them, μ is the amplitude error, and τ is the time error corresponding to the phase error.

[0081] Substituting equation (2) into equation (1) yields the equation of motion of the single-degree-of-freedom system including the test shock absorber taking into account the influence of the loading error, namely:

[0082]

[0083] When the phase error term When Taylor series expansion is used and partial terms are taken for approximation, considering that the high-speed train power system is a high-frequency response system with a relatively large frequency, and the single-degree-of-freedom system including the test shock absorber is the serpentine vibration mode of the high-speed train power system, the frequency ω of the single-degree-of-freedom system is also relatively large, τ 2 The term cannot be ignored. Therefore, in order to analyze the impact of loading error on the solution of the equation, the Taylor expansion containing the phase error term can be expressed as

[0084]

[0085] The acceleration in formula (4) Unknown. In order to solve this problem, the effect of loading is ignored at this time, that is, the jerk is obtained by derivation of formula (3): Right now

[0086]

[0087] Therefore, the phase error term Can be approximated as

[0088]

[0089] Substituting equation (6) into equation (3) and multiplying both sides by m, we can obtain

[0090]

[0091] Formula (7) can be rearranged to obtain

[0092]

[0093] Where, Δm = -μc(τ + ξωτ 2 );

[0094] Formula (8) shows that the loading error introduces mass increment, damping increment and load increment into the system, which all cause certain test errors. Among them, the damping increment may cause the system to become unstable and have an extremely adverse effect. Therefore, the time axis error damping ratio ψ can be defined as c ,Right now As a prediction index of dynamic characteristic compensation. c ≤[ψ c ], where [ψ c ] is to allow the time axis error damping ratio, that is, the phase error is small, then the adverse effect of the loading error on the test can be ignored, and reasonable test results can be obtained without the need for dynamic characteristic compensation; otherwise, the adverse effect of the loading error on the test cannot be ignored, and the dynamic characteristic compensation method must be used to reduce the loading error to ensure the stability of the test and reasonable results.

[0095] In order to solve the problem of loading error introduced into the test due to the nonlinear dynamic characteristics of the loading system itself, the present invention proposes a nonlinear least squares extrapolation compensation method as the dynamic characteristics compensation method in S4 described in the present invention.

[0096] The basic principle of the nonlinear least squares extrapolation compensation method is: select the predicted displacement data set (x j ,y j ), j = i, i-1, ..., im; (x j -x i )=(ji)Δt;Δt=a / f,where Δt is the time step between predicted displacement data points; a is an integer; f is an integer and the sampling frequency. Using trigonometric functions Fit the selected predicted displacement data set; according to the principle of least squares method, minimize the square sum of errors, that is, Among them, the undetermined parameter vector m≥3n. Since P j (t) is nonlinear, so the unknown parameter vector θ cannot be solved by the method of finding the extreme value of the multivariate function, but an iterative algorithm is used to solve it; in order to solve the unknown parameter vector θ more simply, for the selected predicted displacement data set (x j ,y j ), let the current step x i = 0, then x j=(ji)Δt, j = i, i-1, …, im; set the appropriate initial value θ0 of the unknown parameter vector θ, and use the Levenberg-Marquardt algorithm to iterate and solve the parameter vector θ of the objective function F(θ). Finally, perform extrapolation compensation, and Calculate the i-th step command displacement, where τ is the time error corresponding to the phase error.

[0097] S5, the command displacement of the test shock absorber is transmitted by the data interaction system, the command displacement of the test shock absorber is used as the target displacement, and the target displacement is sent to the loading system as a control signal through the real-time simulation calculation system to drive the hydraulic servo actuator to physically load the test shock absorber;

[0098] S6. The measured displacement and measured reaction force of the test shock absorber are measured by the displacement sensor and the force sensor, and the measured reaction force of the test shock absorber is collected by the data acquisition system. Then, based on the data interaction system, the measured reaction force is fed back to the vehicle body numerical model through the real-time simulation calculation system (the measured reaction force is the damping force u generated by the vibration damper); based on the vehicle body numerical model, the corresponding vehicle body motion response is calculated according to the measured reaction force of the test shock absorber and the i+1-step track unevenness effect and wind load excitation in the vehicle body numerical model, and the predicted displacement of the interface between the vehicle body numerical model and the test shock absorber in the next step is determined according to the vehicle body motion response, and the predicted displacement at this moment is stored in the memory to complete data transmission and update;

[0099] S7. Let i=i+1, and repeat S4 to S6 until the test is finished.

[0100] S8. For the S3-S7 test process, an energy-based online monitoring index for test stability is used to monitor the test stability online in real time. If the monitoring index value is negative, that is, the response of the system will be unbounded and the test will be unstable, the test will be terminated directly to avoid unpredictable damage to facilities such as physical specimens and loading systems caused by test instability.

[0101] The test method described in the present invention is to form a feedback closed loop through real-time interaction of the vehicle body numerical model and the test shock absorber through the intersection interface data, wherein the loading error introduced will be continuously accumulated during the test, which will have an adverse effect on the stability of the test. Therefore, in order to ensure the stability of the test, it is necessary to analyze the stability of the test. However, for the test stability problem of the test method described in the present invention, that is, when the train is snaking and unstable, the high-speed train power system itself is unstable, and it is difficult to directly use the existing linear or nonlinear stability analysis method to judge the stability of the test. Therefore, the present invention proposes an energy-based online monitoring index for test stability to analyze the stability of the test in real time.

[0102] In order to clearly describe the energy-based online monitoring index of test stability, the concept of "equivalent specimen" is defined, that is, a virtual specimen whose mechanical properties satisfy the measured force-predicted displacement relationship. In other words, the hysteresis curve of the virtual specimen is the hysteresis curve of the test shock absorber taking into account the loading error. In the test method of the present invention, the dissipated energy includes the energy dissipated by the vehicle body numerical model and the energy dissipated by the equivalent specimen, that is,

[0103] E i =E n +E p

[0104]

[0105]

[0106] Among them, E i The energy dissipated by the entire system is an indicator for evaluating the stability of the system; E n is the energy dissipated by the vehicle body numerical model, which is usually the trapezoidal integral of the work done by the damping force of the vehicle body numerical model on the predicted displacement and the hysteresis energy dissipation of the vehicle body numerical model; E p is the energy dissipated by the equivalent specimen, obtained by the trapezoidal integration of the work done by the measured reaction force on the predicted displacement; f n,i is the damping force of the vehicle body numerical model in step i; f e,i is the measured reaction force of the shock absorber part in the i-th step test; x i and q are the predicted displacement of the i-th step and the total number of test steps, respectively.

[0107] The energy-based online monitoring index of test stability is based on the energy dissipated by the whole system E i As an online monitoring indicator of system stability. Basic principle: If the system is stable, then the system's mechanical energy, external work, and system dissipated energy are all bounded; if the external work and system dissipated energy are all bounded, then the system's mechanical energy is also bounded. Therefore, the bounded energy dissipated by the system can be used as a necessary and sufficient condition for system stability.

[0108] Specifically, in the test method of the present invention, if the vehicle body numerical model does not contain energy-consuming elements (such as shock absorbers), the system energy consumption is equivalent to the energy consumption of the specimen. It can be seen that if the energy consumption of the specimen is positive, the energy of the system will be attenuated and the test will be stable; if the energy consumption of the specimen is negative, the energy of the system will increase and the test may become unstable. If the vehicle body numerical model does not contain energy-consuming elements, only E i is always positive, then the system response will be bounded and the system is stable; if E i is always negative, then the energy of the system will continue to increase and the response of the system will be unbounded, i.e., divergent.

[0109] Furthermore, based on the S4 dynamic characteristic compensation method, in order to further reduce the impact of loading errors, it is possible to use The formula is used to correct the measured reaction force of the i-th step to obtain the measured reaction force correction value; the measured reaction force of the i-th step is replaced by the measured reaction force correction value, and then the measured reaction force correction value is fed back to the vehicle body numerical model (the measured reaction force correction value is substituted into the damping force u generated by the vibration damper in the high-speed train motion equation) until the test is completed. Among them, f e,i are the measured reaction force correction value and the measured reaction force of the shock absorber in the i-th step test respectively; c e is the damping of the test shock absorber; k e is the stiffness of the test shock absorber; x i 、x e,i , and are the predicted displacement, actual displacement, predicted speed and measured speed of the shock absorber in the i-th test respectively.

[0110] That is to say, the aforementioned method is to feed back the measured reaction force to the vehicle body numerical model in step S6, while here the measured reaction force correction value is fed back to the vehicle body numerical model. Specific implementation method 2:

[0112] This embodiment is a high-speed train shock absorber test method provided by the present invention.

[0113] This embodiment uses the shock absorber test of the vehicle-bridge coupling system as an example to explain in detail the test method of the present invention. The vehicle-bridge coupling system is a high-speed train-bridge coupled vibration system. When a high-speed train passes over a bridge at a certain speed, the impact of the train will cause the bridge to vibrate in response, and the vibration response of the bridge will in turn affect the vibration of the train. This mutual influence of vibrations will also produce vehicle-bridge coupled vibrations. The vehicle-bridge coupled vibration will have a great impact on the smoothness and comfort of the train's operation. The test method and system of the present invention can be used to study the working state of the high-speed train shock absorber under actual vehicle-bridge coupled vibration conditions and the coupling effect between the train and the shock absorber. Figure 3 , Figure 4 The present embodiment is described. A high-speed train shock absorber test method described in the present embodiment specifically comprises the following steps:

[0114] Step 1: Divide the train-bridge coupling system into a physical specimen part and a numerical model part. Take a shock absorber of a high-speed train as the physical specimen part, and the remaining train-bridge coupling system part as the numerical model part; according to the parameter information of the train-bridge coupling system, use MATLAB / Simulink to establish the numerical model of the train-bridge coupling system;

[0115] The vehicle-bridge coupling overall system is composed of a high-speed train subsystem and a bridge subsystem, and its motion equation is as follows:

[0116]

[0117] Among them, M v , C v are the mass and damping of the train subsystem; M b , C b are the total mass and total damping matrix of the bridge subsystem; K system =K1+K2 is the overall stiffness matrix of the system, where K1 is the overall stiffness matrix of the vehicle subsystem and the bridge subsystem without considering the coupling term; K2 is the contact matrix between the vehicle and the track. v and F b are the external force load vectors of the train subsystem and the bridge subsystem respectively; X v , and X b , are the displacement, velocity and acceleration vectors of the train subsystem and the bridge subsystem respectively; R is the measured reaction force vector of the test shock absorber.

[0118] Step 2: Install the test shock absorber on the test bench to prepare for loading, compile the numerical model of the train-bridge coupling system using C++ language, download it to the real-time control board corresponding to the real-time simulation computing system, and establish communication between the loading system and the real-time simulation computing system.

[0119] Step 3, assuming that the reaction force of the test train is zero when i=1, based on the train-bridge coupling system numerical model, the predicted displacement of the interface between the train-bridge coupling system numerical model and the test shock absorber is calculated according to the excitation load, and the predicted displacement at time i is stored in the memory;

[0120] Step 4: Compensation prediction index ψ based on dynamic characteristics c , to determine whether dynamic characteristic compensation is needed. If the prediction index ψ c ≤[ψ c ], where [ψ c ] is the allowable time axis error damping ratio, the influence of the loading error can be ignored, and there is no need to perform dynamic characteristic compensation. The predicted displacement of the test shock absorber is directly used as the command displacement to simplify the test process; otherwise, according to the predicted displacement of the test shock absorber, the nonlinear least squares extrapolation compensation method proposed in the present invention is used as the dynamic characteristic compensation method to reduce the phase error and amplitude error generated by the loading system, so that the command displacement of the test shock absorber can be obtained, and the memory is used to store the command at this moment;

[0121] Step 5: The command displacement of the test shock absorber is transmitted by the data interaction system, and the command displacement of the test shock absorber is used as the target displacement. Then, the target displacement is fed back as a control signal to the loading system through the real-time simulation calculation system to drive the hydraulic servo actuator to physically load the test shock absorber specimen;

[0122] Step 6, the measured displacement and measured reaction force of the test shock absorber are measured by the displacement sensor and the force sensor, the measured reaction force of the test shock absorber is collected by the data acquisition system, and then the measured reaction force is fed back to the train-bridge coupling system numerical model through the real-time simulation calculation system based on the data interaction system, and the corresponding train-bridge coupling system motion response is calculated based on the train-bridge coupling system numerical model according to the measured reaction force of the test shock absorber and the i+1th step load excitation, and the predicted displacement of the interface between the train-bridge coupling system numerical model and the test shock absorber in the next step is determined according to the train-bridge coupling system motion response, and the predicted displacement at this moment is stored in the memory;

[0123] Step 7: Let i=i+1, and repeat steps 4 to 6 until the test is finished.

[0124] Step 8. For the test process of steps 3 to 7, an energy-based online test stability monitoring index is used to monitor the test stability online in real time. If the monitoring index value is negative, that is, the response of the system will be unbounded and the test will be unstable, the test will be terminated directly.

[0125] The loading system described in this embodiment adopts an electro-hydraulic servo loading system (such as MTS test system, Fuyun Tianyi loading system, Zhongji test loading system, etc.), including: a host computer, a controller, a hydraulic servo actuator, etc.; the real-time simulation calculation system includes a DSpace system, an xPC target machine, an industrial computer, a NI controller system, etc.

[0126] In step 8 of this embodiment, the energy-based test stability online monitoring index E proposed by the present invention is used. i , the formula is as follows

[0127] E i =E n +E p

[0128]

[0129]

[0130] Among them, E i The energy dissipated by the entire system is an indicator for evaluating the stability of the system; E nis the energy dissipated by the numerical model of the train-bridge coupling system, which is usually the trapezoidal integral of the work done by the damping force of the numerical model of the train-bridge coupling system on the predicted displacement and the hysteresis energy dissipation of the numerical model of the train-bridge coupling system; E p is the energy dissipated by the equivalent specimen, obtained by the trapezoidal integration of the work done by the measured reaction force on the predicted displacement; f n,i is the damping force of the numerical model of the train-bridge coupling system in step i; f e,i is the measured reaction force of the shock absorber part in the i-th step test; x i and q are the predicted displacement of the i-th step and the total number of test steps, respectively.

[0131] Furthermore, based on the dynamic characteristic compensation method in step 4, in order to further reduce the influence of loading error, it is possible to adopt The measured reaction force of step i is corrected by the formula to obtain the measured reaction force correction value; the measured reaction force of step i is replaced by the measured reaction force correction value, and then the measured reaction force correction value is fed back to the numerical model of the train-bridge coupling system (the measured reaction force correction value is substituted into the damping force u generated by the vibration damper in the train-bridge coupling system motion equation) until the end of the test. Among them, f e,i are the measured reaction force correction value and the measured reaction force of the shock absorber in the i-th step test respectively; c e is the damping of the test shock absorber; k e is the stiffness of the test shock absorber; x i 、x e,i , and are the predicted displacement, actual displacement, predicted speed and measured speed of the shock absorber in the i-th test respectively.

[0132] That is to say, the aforementioned method is to feed back the measured reaction force to the numerical model of the train-bridge coupling system in step S6, while here the measured reaction force correction value is fed back to the numerical model of the train-bridge coupling system.

[0133] The drawings of this specification are schematic diagrams, which assist in explaining the concept of the present invention and schematically show the shapes of various parts and their mutual relationships. Although the preferred embodiments of the present invention are described above in conjunction with the drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make various modifications and deformations without departing from the scope of protection of the present invention and the claims, which all belong to the protection scope of the present invention.

Claims

1. A high-speed train shock absorber test method, characterized in that: The following steps are involved: S1. Dividing a test object system including a shock absorber into a physical specimen part and a numerical model part; the test object system is a test object system including a high-speed train; The physical specimen is a shock absorber, which is recorded as the test shock absorber; the numerical model is a numerical model corresponding to the remaining parts of the test object system except the shock absorber, which is recorded as the object numerical model; S2, installing the test shock absorber on the test bench to prepare for loading, compiling and downloading the numerical model to the real-time control board corresponding to the real-time simulation computing system, and establishing communication between the loading system and the real-time simulation computing system; S3, assuming that the reaction force of the test shock absorber is zero when i=1, based on the object numerical model, the predicted displacement of the interface between the object numerical model and the test shock absorber in the next step is calculated according to the load action in the object numerical model, and the predicted displacement at time i is stored in the memory; S4. judging whether dynamic characteristic compensation is required according to the dynamic characteristic of the test shock absorber, and if dynamic characteristic compensation is not required, directly taking the predicted displacement of the test shock absorber as the command displacement; Otherwise, according to the predicted displacement of the test shock absorber, the loading error generated by the loading system is reduced by a dynamic characteristic compensation method, thereby obtaining a command displacement of the test shock absorber; and a memory is used to store the command displacement at this moment; S5, the command displacement of the test shock absorber is transmitted by the data interaction system, the command displacement of the test shock absorber is used as the target displacement, and the target displacement is sent to the loading system as a control signal through the real-time simulation calculation system to drive the hydraulic servo actuator to physically load the test shock absorber; S6. The measured displacement and measured reaction force of the test shock absorber are measured by the displacement sensor and the force sensor, the measured reaction force of the test shock absorber is collected by the data acquisition system, and then the measured reaction force is fed back to the object numerical model through the real-time simulation calculation system based on the data interaction system; based on the object numerical model, the motion response of the corresponding object system is calculated according to the measured reaction force of the test shock absorber and the load action of the i+1th step in the object numerical model, and the predicted displacement of the interface between the object numerical model and the test shock absorber in the next step is determined according to the motion response, and the predicted displacement at this moment is stored in the memory to complete data transmission and update; S7. Let i=i+1, and repeat S4 to S6 until the test is finished.

2. A high-speed train shock absorber test method according to claim 1, characterized in that: In the process of feeding back the measured reaction force to the object numerical model through the real-time simulation calculation system based on the data interaction system in S6, the measured reaction force is replaced by the measured reaction force correction value, and then the measured reaction force correction value is fed back to the object numerical model; The calculation formula of the measured reaction force correction value is as follows: in, f e,i are the measured reaction force correction value and the measured reaction force of the shock absorber in the i-th step test respectively; c e is the damping of the test shock absorber; k e is the stiffness of the test shock absorber; x i 、x e,i , and are the predicted displacement, actual displacement, predicted speed and measured speed of the shock absorber in the i-th test respectively.

3. A high-speed train shock absorber test method according to claim 1 or 2, characterized in that: The method also includes the step of online real-time monitoring of test stability, that is, for the S3-S7 test process, an energy-based online monitoring index of test stability is used to monitor the test stability online in real time.

4. A high-speed train shock absorber test method according to claim 3, characterized in that: The energy-based test stability online monitoring indicators are as follows: AND i =And n +E p Among them, E i The energy dissipated by the entire system is an indicator for evaluating the stability of the system; E n is the energy dissipated by the object numerical model, is the trapezoidal integral of the work done by the damping force of the object numerical model on the predicted displacement, and is the hysteresis energy dissipated by the object numerical model; E p is the energy dissipated by the equivalent specimen, obtained by the trapezoidal integration of the work done by the measured reaction force on the predicted displacement. The equivalent specimen is a virtual specimen whose mechanical properties satisfy the measured force-predicted displacement relationship; f n,i is the damping force of the numerical model part of the object in step i; f e,i is the measured reaction force of the shock absorber part in the i-th step test; x i and q are the predicted displacement of the i-th step and the total number of test steps, respectively.

5. A high-speed train shock absorber test method according to claim 4, characterized in that: In the process of online real-time monitoring of test stability using energy-based test stability online monitoring indicators, if the monitoring indicator E i is positive, then the structural response will be bounded and the system will be stable; if the monitoring index E i If it is negative, the response of the system will be unbounded and the test will be unstable, then the test will be terminated directly.

6. A high-speed train shock absorber test method according to claim 5, characterized in that: In the process of judging whether dynamic characteristic compensation is required according to the dynamic characteristics of the test shock absorber as described in S4, the time axis error damping ratio ψ c As a prediction index for dynamic characteristic compensation, if the prediction index ψ c ≤[ψ c ], where [ψ c ] is the allowable time axis error damping ratio, then there is no need to perform dynamic characteristic compensation, otherwise it is necessary to perform dynamic characteristic compensation; The time axis error damping ratio is as follows: Among them, τ is the time error corresponding to the phase error, and ω is the system's serpentine vibration circular frequency.

7. A high-speed train shock absorber test method according to claim 6, characterized in that: When dynamic characteristic compensation is required, a nonlinear least squares extrapolation compensation method is used as the dynamic characteristic compensation method.

8. A high-speed train shock absorber test method according to claim 7, characterized in that: The object system is a high-speed train system; the object numerical model is a vehicle body numerical model; The numerical model of the car body is expressed in the form of motion equations. The motion equations of high-speed trains are as follows: Where M, C and K are the mass, damping and stiffness matrices of the train system respectively; X is the displacement vector of each degree of freedom, is the first derivative of X, is the second-order derivative of X; u is the damping force vector generated by the test shock absorber; w is the linear or nonlinear wheel-rail contact force, which is related to the wheel-rail model and track irregularity; l u and l w is the coefficient matrix, which is related to the test shock absorber installation and track irregularity respectively; F is the wind load vector borne by the train at high speed; S6 is a process of calculating the motion response of the corresponding object system based on the measured reaction force of the test shock absorber and the i+1-step load action in the object numerical model, that is, a process of calculating the corresponding vehicle body motion response based on the measured reaction force of the test shock absorber and the i+1-step track unevenness action and wind load excitation in the vehicle body numerical model.

9. A high-speed train shock absorber test method according to claim 7, characterized in that: The object system is a train-bridge coupling system; the object numerical model is a train-bridge coupling system numerical model; The train-bridge coupling system is composed of a high-speed train subsystem and a bridge subsystem, and its motion equation is as follows: Among them, M v , C v are the mass and damping of the train subsystem; M b , C b are the total mass and total damping matrix of the bridge subsystem; K system =K1+K2 is the overall stiffness matrix of the system, where K1 is the overall stiffness matrix of the vehicle subsystem and the bridge subsystem without considering the coupling term; K2 is the contact matrix between the vehicle and the track; F v and F b are the external force load vectors of the train subsystem and the bridge subsystem respectively; X v , and X b , are the displacement, velocity, and acceleration vectors of the train subsystem and the bridge subsystem, respectively; R is the measured reaction force vector of the test shock absorber; S6 is the process of calculating the motion response of the corresponding object system based on the measured reaction force of the test shock absorber and the i+1-step load action in the object numerical model, that is, the process of calculating the motion response of the corresponding train-bridge coupling system based on the measured reaction force of the test shock absorber and the i+1-step load excitation.

10. A high-speed train shock absorber test system, implemented by using a high-speed train shock absorber test method according to any one of claims 1 to 9, characterized in that: A real-time simulation calculation system is used to calculate the response of the numerical model in real time and determine whether dynamic characteristic compensation is required based on the dynamic characteristics of the test shock absorber. If dynamic characteristic compensation is not required, the predicted displacement of the test shock absorber is directly used as the command displacement; Otherwise, the loading error generated by the loading system is reduced by a dynamic characteristic compensation method according to the predicted displacement of the test shock absorber, thereby obtaining the command displacement of the test shock absorber; The loading system drives the actuator to achieve dynamic command displacement of the shock absorber; Data acquisition system, used to collect the actual displacement and reaction force of the shock absorber; The data interaction system is used to realize the communication between the real-time simulation computing system and the loading system.

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