CN114781097A - High-speed train shock absorber test system and method - Google Patents
High-speed train shock absorber test system and method Download PDFInfo
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Abstract
A high-speed train shock absorber test system and a method belong to the technical field of train test simulation. The invention can solve the problems of high cost, long period, incapability of realizing extreme working conditions and incapability of considering the coupling effect in the performance test of the whole vehicle. The system comprises a loading system which enables the shock absorber to realize dynamic command displacement through a driving actuator, a data acquisition system which is used for acquiring the actual displacement and the counterforce of the shock absorber, a real-time simulation calculation system which is used for calculating the response of a numerical model in real time, completing dynamic characteristic compensation, sending a loading system command and monitoring the test stability on line, and a data interaction system which is used for realizing the communication between the real-time simulation calculation system and the loading system. And judging whether the dynamic characteristic compensation is needed or not according to the dynamic characteristic of the test shock absorber in the process of completing the dynamic characteristic compensation, and reducing the loading error generated by a loading system by using a dynamic characteristic compensation method so as to obtain the command displacement of the test shock absorber.
Description
Technical Field
The invention belongs to the technical field of train test simulation, and particularly relates to a test method for a shock absorber of a high-speed train.
Background
In recent years, domestic high-speed trains enter a high-speed development period, and achieve a plurality of breakthrough achievements, and are popular due to safe and stable operation. However, with the occurrence and development of factors influencing train performance such as wheel rail abrasion, subgrade settlement, device aging and the like, the running performance of a high-speed train gradually deteriorates, and how to keep good running stability becomes a problem to be solved urgently. The transverse and snaking vibration of the high-speed train in operation not only can aggravate the abrasion of the wheel track and influence the running stability of the train, but also can reduce the running safety of the train and increase the derailment risk of the train. Meanwhile, a high-speed train usually runs on a bridge, and axle coupling vibration also occurs between the high-speed train and the bridge. The dynamic pressure of wind and the train running at high speed generate power action on the bridge, and the bridge generates corresponding vibration response, and the vibration further excites the train to vibrate. Therefore, the axle coupling vibration has a great influence on the smoothness and comfort of the train. The installation of the shock absorber is an effective measure for inhibiting the undesirable vibration of the train, and can improve the instability critical speed of the train, the running comfort and the system life. The stress state of the shock absorber in the running process of the train and the dynamic coupling relation between the shock absorber and the train body are researched, and the shock absorber has important values for further improving the running speed, the running stability and the safety of the train.
At present, the testing means of the high-speed train shock absorber can be mainly divided into two types: one is to use a vibration test bed to test the whole train or the underframe of the train; the other is to use a vibration damper tester to perform tests on the performance of the vibration damper. The former can reproduce the coupling effect between the damper and the whole train or the underframe of the train, but is not suitable for damper research and test work requiring a large number of tests due to high test cost. The latter generally uses an actuator to perform a specific-course loading test on the shock absorber, and although the test cost is relatively low, the coupling effect between the shock absorber and the rest of the train cannot be considered, so that the influence of the shock absorber on the dynamic behavior of the train is difficult to accurately evaluate. In view of the above, the invention provides a high-speed train shock absorber test system and method, which can make up for such deficiencies and have outstanding advantages and wide application prospects.
Disclosure of Invention
Aiming at the requirements of shock absorber test evaluation, the invention provides a high-speed train shock absorber test system and a high-speed train shock absorber test method, aiming at solving the problems that the cost of a finished train test is high, the period is long, the extreme working condition cannot be realized, and the coupling effect cannot be considered in a performance test.
A high speed train shock absorber testing system comprising:
the real-time simulation computing system is used for computing the response of the numerical model in real time, judging whether dynamic characteristic compensation is needed or not according to the dynamic characteristic of the test shock absorber, and directly taking the predicted displacement of the test shock absorber as a command displacement if the dynamic characteristic compensation is not needed; otherwise, reducing the loading error generated by the loading system by a dynamic characteristic compensation method according to the predicted displacement of the test shock absorber so as to obtain the command displacement of the test shock absorber;
the loading system enables the shock absorber to realize dynamic command displacement through the driving actuator;
the data acquisition system is used for acquiring the actual displacement and the counterforce of the shock absorber;
and the data interaction system is used for realizing communication between the real-time simulation computing system and the loading system, such as sending the counter force of the shock absorber to the real-time simulation computing system.
A test method for a high-speed train shock absorber comprises the following steps:
s1, dividing an object system comprising the shock absorber into a physical test piece part and a numerical model part; the object system is a test object system comprising a high-speed train;
the physical test piece is a shock absorber and is marked as a test shock absorber; the numerical model is a numerical model corresponding to the rest part except the shock absorber in the test object system and is marked as an object numerical model;
s2, mounting the test shock absorber on a test bed for loading, compiling and downloading the numerical model to a real-time control board card 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 is equal to 1, calculating the predicted displacement of the interface between the next target numerical model and the test shock absorber according to the load action in the target numerical model based on the target numerical model, and storing the predicted displacement at the moment i by adopting a memory;
s4, judging whether dynamic characteristic compensation is needed according to the dynamic characteristics of the test shock absorber, and directly taking the predicted displacement of the test shock absorber as a command displacement if the dynamic characteristic compensation is not needed; otherwise, reducing the loading error generated by the loading system 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; storing the command displacement at the moment by adopting a memory;
s5, transmitting the command displacement of the test shock absorber by the data interaction system, taking the command displacement of the test shock absorber as a target displacement, sending the target displacement as a control signal to a loading system through the real-time simulation computing system, and driving the hydraulic servo actuator to physically load the test shock absorber;
s6, measuring the actual measurement displacement and the actual measurement counter force of the test shock absorber through the displacement sensor and the force sensor, acquiring the actual measurement counter force of the test shock absorber through the data acquisition system, and then feeding the actual measurement counter force 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, calculating the motion response of a corresponding object system according to the actual measurement reaction force of the test shock absorber and the (i + 1) th step load action in the object numerical model, determining the predicted displacement of the interface of the next step object numerical model and the test shock absorber according to the motion response, and storing the predicted displacement at the moment by adopting a memory so as to complete data transmission and updating;
s7, i is made to i +1, and S4 to S6 are repeated until the end of the test.
Further, in the process that the real-time simulation calculation system feeds back the actual measurement reaction force to the object numerical model based on the data interaction system in S6, the actual measurement reaction force is replaced by the actual measurement reaction force correction value, and then the actual measurement reaction force correction value is fed back to the object numerical model;
the actual measurement reaction correction value calculation formula is as follows:
wherein, the first and the second end of the pipe are connected with each other,
fe,irespectively obtaining an actual measurement counter force correction value and an actual measurement counter force of the shock absorber in the step i; c. CeTesting the damping of the shock absorber; k is a radical ofeTo test the stiffness of the shock absorber; x is a radical of a fluorine atomi、xe,i、
And
the predicted displacement, the actual displacement, the predicted speed and the actual measurement speed of the shock absorber in the ith step are respectively.
Further, the method also comprises a step of monitoring the test stability in real time on line, namely, aiming at the test process from S3 to S7, an energy-based test stability on-line monitoring index is adopted to monitor the test stability in real time on line.
Further, the on-line monitoring indexes of the test stability based on energy are as follows:
Ei＝En+Ep
wherein E isiThe energy dissipated by the whole system is an index for evaluating the stability of the system; enEnergy dissipated for the object numerical model, trapezoidal integral of the damping force of the object numerical model acting on the prediction displacement and hysteretic energy consumption of the object numerical model; epThe energy dissipated by the equivalent test piece is obtained by trapezoidal integration of actually measured counter force acting on the predicted displacement, and the equivalent test piece is a virtual test piece with mechanical properties meeting the relation of the actual force and the predicted displacement; f. ofn,iThe damping force of the object numerical model part in the ith step; f. ofe,iTesting the actually measured reaction force of the shock absorber part in the ith step; x is the number ofiAnd q are the predicted displacement of the ith step and the total number of test steps respectively.
Further, in the process of monitoring the test stability on line in real time by adopting the test stability on-line monitoring index based on energy, if the index E is monitorediIf positive, the system response will be bounded and the system will stabilize; if monitoring the index EiIf the response is negative, i.e. the response of the system will be unbounded, the test is unstable, and the test is ended directly.
Further, in the process of determining whether dynamic characteristic compensation is required according to the dynamic characteristics of the test damper in S4, a time axis error damping ratio ψ is usedcAs a power characteristic compensation prediction index, if the prediction index psic≤[ψc]Wherein [ psic]If the time axis error damping ratio is allowed, dynamic characteristic compensation is not needed, otherwise, the dynamic characteristic compensation is needed;
the time axis error damping ratio is as follows:
wherein, tau is the time error corresponding to the phase error, and omega is the snaking vibration circle frequency of the system.
Further, when the dynamic characteristic compensation is required, a nonlinear least square extrapolation compensation method is adopted as the dynamic characteristic compensation method.
Furthermore, the object system is a high-speed train system; the object numerical model is a vehicle body numerical model;
the numerical model of the train body is embodied in the form of a motion equation, and the motion equation of the high-speed train is as follows:
wherein M, C and K are the mass, damping and stiffness matrices of the train system, respectively; x is a displacement vector of the respective degree of freedom,
is the first derivative of X and is,
is the second derivative of X; u is a damping force vector generated by the test shock absorber; w is a linear or non-linear wheel-rail contact force, and is related to a wheel-rail model, rail irregularity and the like; luAnd lwThe coefficient matrix is respectively related to the installation of the test shock absorber, the irregularity of the track and the like; f is a wind load vector borne by the train running at high speed;
in S6, the motion response of the corresponding target system is calculated according to the measured reaction force of the test damper and the load action at step i +1 in the target numerical model, that is, the corresponding vehicle motion response is calculated according to the measured reaction force of the test damper and the track irregularity action and the wind load excitation at step i +1 in the vehicle numerical model.
Or, the object system is a train-bridge coupling system; an object numerical model is a train-bridge coupling system numerical model;
the train-bridge coupling system consists of a high-speed train subsystem and a bridge subsystem, and the motion equation is as follows:
wherein, Mv、CvRespectively the train subsystem mass and the damping; mb、CbRespectively the total mass and the total damping matrix of the bridge subsystem; ksystem＝K1+K2Is the global stiffness matrix of the system, where K1The integral rigidity matrix of the coupling item is not considered for the vehicle subsystem and the bridge subsystem; k2A contact matrix of the vehicle and the track; fvAnd FbRespectively are external force load vectors borne by the train subsystem and the bridge subsystem; xv，
And Xb，
Respectively are displacement, speed and acceleration vectors of the train subsystem and the bridge subsystem; r is an actually measured reaction force vector of the test shock absorber;
and in S6, calculating the motion response of the corresponding object system according to the measured reaction force of the test shock absorber and the load action of the (i + 1) th step in the object numerical model, namely calculating the motion response of the corresponding train-bridge coupling system according to the measured reaction force of the test shock absorber and the load excitation of the (i + 1) th step.
The invention has the beneficial effects that:
the invention provides a high-speed train shock absorber test system and a method, which are characterized in that the physical loading of a real shock absorber and the solving of a train numerical model (which can comprise a bridge model, a wind field model, a seismic model and the like according to requirements) are synchronously carried out, the physical loading and the solving of the train numerical model and the physical loading and the solving of the train numerical model interact data in real time, and the stress process of the shock absorber and the coupling action of the shock absorber and a train can be accurately reproduced; only the shock absorber is used as an actual test piece, so that the test cost and the test period are greatly saved compared with the whole vehicle test; the rest parts of the train are simulated by adopting a numerical method, so that the requirement on test equipment is reduced; train power behaviors under different working conditions can be simulated by adjusting parameters, and test efficiency and test detection capability under extreme working conditions are improved.
Drawings
For convenience of explanation, the invention is described in detail in the following detailed description and the accompanying drawings.
FIG. 1 is a flow chart of a testing method of a high speed train shock absorber testing system;
FIG. 2 is a schematic diagram of a testing method principle of a high-speed train shock absorber testing system;
FIG. 3 is a flow chart of a test method, such as an axle coupling system shock absorber test;
FIG. 4 is a schematic diagram illustrating a testing method for testing the shock absorber of the axle coupling system.
Detailed Description
In order that the objects, aspects and advantages of the invention will become more apparent, the invention will be described by way of example only, and in connection with the accompanying drawings. It is to be understood that such description is merely illustrative and not intended to limit the scope of the present invention. It should be noted that, in order to avoid obscuring the present invention with unnecessary detail, only the structures and processing steps that are closely related to the scheme of the present invention are shown in the drawings, and other details that are not relevant are omitted.
The high-speed train shock absorber testing method is realized by means of a high-speed train shock absorber testing system, and the high-speed train shock absorber testing system comprises a real-time simulation computing system, a loading system, a data acquisition system, a data interaction system and the like;
the real-time simulation computing system is used for computing the response of the numerical model in real time, completing the compensation of the dynamic characteristics and sending a loading system command; completing the process of power characteristic compensation: judging whether dynamic characteristic compensation is needed according to the dynamic characteristics of the test shock absorber, and directly taking the predicted displacement of the test shock absorber as a command displacement if the dynamic characteristic compensation is not needed; otherwise, reducing the loading error generated by the loading system 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 enables the shock absorber to realize dynamic command displacement through the driving actuator;
the data acquisition system is used for acquiring the actual displacement and the counterforce of the shock absorber;
and the data interaction system is used for realizing communication between the real-time simulation computing system and the loading system, such as sending the counter force of the shock absorber to the real-time simulation computing system.
The invention relates to a test method of a high-speed train shock absorber, which simulates the main parts of dynamic systems such as trains, shock absorbers, bridges, earthquakes, wind and the like through a simulation technology, simulates a single key shock absorber through a physical test, and carries out a test on the test system, thereby evaluating the dynamic performance of the shock absorber and the coupling effect with the surrounding environment with low cost, high efficiency and accuracy.
In order to fully explain the invention, a method for testing a shock absorber of a high-speed train is explained in more detail through specific embodiments.
The first embodiment is as follows: this embodiment will be described with reference to FIGS. 1 and 2,
the embodiment is a test method for a shock absorber of a high-speed train.
A test method for a shock absorber of a high-speed train specifically comprises the following steps:
s1, dividing the high-speed train into a physical test piece part and a numerical model part; the physical test piece is a shock absorber of the high-speed train and is marked as a test shock absorber; the numerical model is a numerical model corresponding to the rest vehicle body parts except the shock absorber, can be established by adopting MATLAB/Simulink and is marked as a vehicle body numerical model.
The vehicle body numerical model is embodied in the form of a motion equation, and parameters of the vehicle body numerical model comprise vehicle body mass and rotary inertia, framework mass and rotary inertia, wheel set mass and rotary inertia, spring stiffness and shock absorber damping coefficient of a primary system and a secondary system, each size of a vehicle, wheel-rail contact model parameters, track irregularity information and the like; the model can also comprise a train running speed, a bridge model, a train-air coupling model and the like, and can also consider more factor models according to actual conditions. The equation of motion of the high-speed train can be expressed as
Wherein M, C and K are the mass, damping and stiffness matrices of the train system, respectively; x is a displacement vector of the respective degree of freedom,
is the first derivative of X and is,
is the second derivative of X; u is a damping force vector generated by the test shock absorber; w is a linear or non-linear wheel-rail contact force, related to wheel-rail models, rail irregularities, etc.; l. theuAnd lwThe coefficient matrix is respectively related to the installation of the test shock absorber, the irregularity of the track and the like; and F is a wind load vector borne by the train running at high speed.
And parameters of the vehicle body numerical model at the ith moment are stored in a memory, and the parameters are transmitted to a vehicle body numerical model motion equation in the real-time simulation calculation system by the data interaction system to calculate the predicted displacement at the i +1 moment in real time.
And S2, mounting the test shock absorber on a test bed for loading, compiling and downloading the numerical model of the vehicle body to a real-time control board card corresponding to the real-time simulation computing system by adopting C language, and establishing communication between the loading system and the real-time simulation computing system.
The loading system adopts an electro-hydraulic servo loading system (such as an MTS test system, a Fuyun wing loading system, a middle aircraft test loading system and the like), and comprises: the device comprises an upper computer, a controller, a hydraulic servo actuator and the like.
The real-time simulation computing system comprises but is not limited to a DSpace system, an xPC target machine, an industrial personal computer, an NI controller system and the like.
S3, assuming that the reaction force of the test shock absorber is zero when i is equal to 1, calculating the predicted displacement of the interface between the next vehicle body numerical model and the test shock absorber according to the track irregularity and the wind load excitation in the vehicle body numerical model at the moment based on the vehicle body numerical model, and storing the predicted displacement at the moment i by adopting a memory;
the track irregularity is track irregularity in a time domain by processing the track power spectral density by adopting the track power spectral density. Converting a single-side power spectral density function with unsmooth track into a double-side function and performing discretization sampling treatment; and calculating the frequency spectrum of the track irregularity according to the discretization sampling result, and performing fast Fourier inverse transformation to obtain the time sequence of the track irregularity. And reflecting time series information of track irregularity through w of the motion equation, and calculating the predicted displacement of the joint surface of the vehicle body numerical model and the test shock absorber in the next step in real time through the motion equation of the numerical model according to the track irregularity effect, the wind load excitation and the actual measurement counter force of the test shock absorber in the step i transmitted to the vehicle body numerical model.
S4, compensating the prejudgment index psi based on the dynamic characteristicscTo determine in advance whether or not the power characteristic compensation is required. If the prejudged index psic≤[ψc]Wherein [ psic]In order to allow the time axis error damping ratio, the influence of the loading error can be ignored, dynamic characteristic compensation is not needed, and the predicted displacement of the test shock absorber is directly used as command displacement so as to simplify the test process; otherwise, according to the predicted displacement of the test shock absorber, reducing a loading error (phase error and amplitude error) generated by a loading system by a dynamic characteristic compensation method so as to obtain a command displacement of the test shock absorber, and storing the command displacement at the moment by adopting a memory;
in order to judge whether the test method needs dynamic characteristic compensation in advance to obtain a reasonable test result, the invention analyzes the influence of loading errors on the test method, thereby providing a dynamic characteristic compensation prejudgment index. In order to describe the dynamic characteristic compensation prejudgment index more clearly, only a single-degree-of-freedom system motion equation comprising a test shock absorber is adopted for derivation, the single-degree-of-freedom system comprising the test shock absorber is a snaking vibration mode of a high-speed train dynamic system, and the derivation process is as follows:
the single-degree-of-freedom system motion equation comprising the test shock absorber comprises the following steps:
wherein the content of the first and second substances,
ξ＝cev (2 · m · ω); m and k are the mass and stiffness of the system, respectively; x, x,
And f is the displacement, acceleration and external force of the system respectively; omega and xi are respectively the snaking vibration circle frequency of the system and the damping ratio of the test shock absorber; t represents time; c. CeIt is the damping of the test shock absorber,
the first derivative of the test damper displacement, i.e., the actual velocity of the test damper, is represented. It should be noted that the displacement x, velocity of the system
And acceleration
I.e., the predicted displacement, velocity and acceleration of the test shock absorber.
Testing the actual speed of the shock absorber at the moment t due to the loading error
And predicted speed
Different. Using actuator models taking into account amplitude and phase errors, having
Where μ is the amplitude error and τ is the time error corresponding to the phase error.
Substitution of equation (2) for equation (1) the described equation of motion for a single degree of freedom system including a test damper, which takes into account the effect of loading errors, i.e.
When it is aligned with the phase error term
When Taylor series expansion is adopted and partial terms are approximate, the high-speed train power system is considered to be a high-frequency response system with higher frequency, and the single-degree-of-freedom system comprising the test shock absorber is a snaking vibration mode of the high-speed train power system, so that the frequency omega of the single-degree-of-freedom system is higher, and the tau is higher2The entries cannot be ignored. Thus, to analyze the effect of loading error on the solution of the equation, the Taylor expansion with phase error term can be expressed as
Acceleration in formula (4)
Is unknown. To solve this problem, the influence of the loading is ignored, i.e. the jerk is derived from equation (3)
Namely that
Therefore, including the phase error term
Can be approximated by
By substituting formula (6) for formula (3) and multiplying both sides by m
Can be obtained by finishing the formula (7)
Wherein, Δ m ═ μ c (τ + ξ ω τ)2)；
The equation (8) shows that the loading error introduces mass increment, damping increment and load increment into the system, and all cause certain test errors, wherein the damping increment can cause the system to be unstable, and extremely adverse effects are generated. Thus, a time axis error damping ratio ψ can be definedcI.e. by
As a power characteristic compensation anticipation index. If psic≤[ψc]Wherein [ psic]The damping ratio of time axis error is allowed, namely the phase error is smaller, the adverse effect of loading error on the test can be ignored, and a reasonable test result can be obtained without adopting dynamic characteristic compensation; on the contrary, the adverse effect of the loading error on the test cannot be ignored, and the dynamic characteristic compensation method must be adopted to reduce the loading error so as to ensure the stability of the test and reasonable result.
Aiming at the problem that loading errors are introduced for tests due to the nonlinear dynamic characteristics of a loading system, the invention provides a nonlinear least square extrapolation compensation method as the dynamic characteristic compensation method in S4.
SaidThe basic principle of the nonlinear least square extrapolation compensation method is as follows: selecting the predicted displacement data set (x) of the current ith step and the past stepj,yj)，j＝i,i-1,…,i-m；(xj-xi) (j-i) Δ t; Δ t ═ a/f, where Δ t is the time step between predicted displacement data points; a is an integer; f is an integer as the sampling frequency. Using trigonometric functions
Fitting the selected predictive displacement data set; according to the principle of least squares, the sum of squares of the errors is minimised, i.e.
Wherein the undetermined parameter vector
m is more than or equal to 3 n. Due to PjThe nonlinearity of (t), so the undetermined parameter vector theta cannot be solved by a method for solving an extremum of a multivariate function, but an iterative algorithm is adopted for solving; for a more concise solution to the undetermined parameter vector θ, the displacement data set (x) is predicted for the selected predictionj,yj) Let the current ith step xiWhen being equal to 0, x isj(j-i) Δ t, j ═ i, i-1, …, i-m; setting an initial value theta of a suitable undetermined parameter vector theta0Iteration is carried out by adopting a Levenberg-Marquardt algorithm, and a parameter vector theta of the target function F (theta) is solved. Finally, extrapolation compensation is performed by
And calculating the command displacement of the ith step, wherein tau is a time error corresponding to the phase error.
S5, transmitting the command displacement of the test shock absorber by the data interaction system, taking the command displacement of the test shock absorber as a target displacement, sending the target displacement as a control signal to the loading system through the real-time simulation computing system, and driving the hydraulic servo actuator to physically load the test shock absorber;
s6, measuring the actual measurement displacement and the actual measurement counter force of the test shock absorber through the displacement sensor and the force sensor, acquiring the actual measurement counter force of the test shock absorber through the data acquisition system, and then feeding the actual measurement counter force back to the car body numerical model (the actual measurement counter force is the damping force u generated by the shock absorption damper) through the real-time simulation calculation system based on the data interaction system; based on the vehicle body numerical model, calculating corresponding vehicle body motion response according to the actually measured counter force of the test shock absorber and the irregularity of the track at the (i + 1) th step in the vehicle body numerical model and wind load excitation, determining the predicted displacement of the joint surface of the vehicle body numerical model and the test shock absorber at the next step according to the vehicle body motion response, and storing the predicted displacement at the moment by adopting a memory so as to complete data transmission and updating;
s7, i equals i +1, and S4 to S6 are repeated until the test is completed.
S8, for the S3-S7 test process, adopting an energy-based test stability online monitoring index to monitor the test stability online in real time; if the monitoring index value is negative, namely the response of the system is unbounded, the test is unstable, the test is directly ended, and unpredictable damage to facilities such as a physical test piece, a loading system and the like caused by the test instability is avoided.
The test method provided by the invention is characterized in that a vehicle body numerical model and a test shock absorber are interacted in real time through intersecting interface data to form a feedback closed loop, wherein the introduced loading error can be accumulated continuously in the test, and the adverse effect can be brought to the stability of the test. Therefore, to ensure the stability of the test, the stability of the test needs to be analyzed. However, the test stability problem of the test method of the invention is that when the train has hunting instability, the power system of the high-speed train is unstable, and the stability of the test is difficult to be judged by directly adopting the existing linear or nonlinear stability analysis method. Therefore, the invention provides an energy-based test stability on-line monitoring index, and the test stability is analyzed in real time.
In order to clearly describe the online monitoring index of the test stability based on energy, an equivalent test piece concept is defined, namely a virtual test piece with mechanical characteristics meeting the relation of practical force-predicted displacement. In other words, the hysteresis curve of the virtual test piece is the hysteresis curve of the test damper in consideration of the loading error. In the test method of the invention, the dissipated energy includes the energy dissipated by the numerical model of the vehicle body and the energy dissipated by the equivalent test piece, i.e. the energy dissipated by the equivalent test piece
Ei＝En+Ep
Wherein E isiThe energy dissipated by the whole system is an index for evaluating the stability of the system; enThe energy dissipated by the vehicle body numerical model is usually trapezoidal integral of the damping force of the vehicle body numerical model acting on the predicted displacement and hysteretic energy consumption of the vehicle body numerical model; epThe energy dissipated by the equivalent test piece is obtained by trapezoidal integration of the work done by the actual measurement counter force on the prediction displacement; f. ofn,iThe damping force of the vehicle body numerical model part in the ith step is obtained; f. ofe,iTesting the actually measured reaction force of the shock absorber part in the ith step; x is a radical of a fluorine atomiAnd q are the predicted displacement of the ith step and the total number of test steps respectively.
The test stability on-line monitoring index based on energy is that the whole system is adopted to dissipate energy EiAs an on-line monitoring indicator of system stability. The basic principle is as follows: if the system is stable, the mechanical energy, the external force acting and the energy dissipated by the system are bounded; if the external force does work and the energy dissipated by the system is bounded, the mechanical energy of the system is also bounded. Therefore, the energy dissipated by the system is bounded as a sufficient requirement for system stability.
Specifically, in the test method of the present invention, the car body numerical model does not contain dissipative elements (such as dampers), and the system dissipation is the equivalent test piece dissipation. Therefore, if the energy consumption of the test piece is positive, the energy of the system is attenuated, and the test is stable; if the test piece consumes negative energy, the system energy will increase, and the test can be carried outCan be destabilized. For a numerical model of the car body without dissipative elements, only E is requirediAlways positive, then the system response will be bounded and the system will stabilize; if EiAlways negative, the system energy will continue to increase and the response of the system will be unbounded, i.e. divergent.
Further, on the basis of the S4 dynamic characteristic compensation method, in order to further reduce the influence of loading error, a method of compensating for the dynamic characteristic may be adopted
Correcting the measured reaction force in the ith step by a formula to obtain a measured reaction force correction value; and replacing the measured reaction force in the ith step with a measured reaction force correction value, and feeding back the measured reaction force correction value to the numerical model of the train body (the measured reaction force correction value substitutes the damping force u generated by the vibration damping damper in the motion equation of the high-speed train) until the test is finished. Wherein the content of the first and second substances,
fe,irespectively obtaining an actual measurement counter force correction value and an actual measurement counter force of the shock absorber in the step i; c. CeTesting the damping of the shock absorber; k is a radical ofeTo test the stiffness of the shock absorber; x is the number ofi、xe,i、
And
the predicted displacement, the actual displacement, the predicted speed and the actual measurement speed of the shock absorber in the ith step are respectively.
That is, in the above-described embodiment, the actual measurement reaction force is fed back to the vehicle body numerical model in step S6, and the actual measurement reaction force correction value is fed back to the vehicle body numerical model in this case.
The second embodiment is as follows:
the embodiment is a test method for a shock absorber of a high-speed train.
In the embodiment, the test method is elaborated by taking the shock absorber test of the axle coupling system as an example, wherein the axle coupling system is a high-speed train-bridge coupling vibration system. When a high-speed train passes through a bridge at a certain running speed, the bridge generates vibration response due to the impact power of the train, the vibration response of the bridge in turn influences the vibration of the train, and the mutual influence of the vibration also generates axle coupling vibration. The axle coupling vibration can greatly affect the running stability and comfort of the train, and the working state of the high-speed train shock absorber under the condition of actual axle coupling vibration and the coupling effect of the train and the shock absorber can be researched by the testing method and the testing system. The embodiment is described with reference to fig. 3 and 4, and the method for testing the shock absorber of the high-speed train in the embodiment specifically includes the following steps:
step 1, dividing an axle coupling system into a physical test piece part and a numerical model part. Taking a shock absorber of a high-speed train as a physical test piece part, and taking the rest train-bridge coupling system part as a numerical model part; according to the parameter information of the train-bridge coupling system, adopting MATLAB/Simulink to establish a numerical model of the train-bridge coupling system;
the axle coupling integral system consists of a high-speed train subsystem and a bridge subsystem, and the motion equation is as follows:
wherein M isv、CvRespectively the train subsystem mass and damping; m is a group ofb、CbRespectively the total mass and the total damping matrix of the bridge subsystem; k issystem＝K1+K2Is the global stiffness matrix of the system, where K1The integral rigidity matrix of the coupling item is not considered for the vehicle subsystem and the bridge subsystem; k2Is the contact matrix of the vehicle and the track. FvAnd FbRespectively are external force load vectors borne by the train subsystem and the bridge subsystem; xv，
And Xb，
Respectively are displacement, speed and acceleration vectors of the train subsystem and the bridge subsystem; r is the measured reaction vector of the test damper.
And 2, installing the test shock absorber on a test bed for loading, compiling and downloading the numerical model of the train-bridge coupling system to a real-time control board card corresponding to the real-time simulation computing system by adopting C + + language, and establishing communication between the loading system and the real-time simulation computing system.
Step 3, assuming that the counter force of the test train is zero when i is equal to 1, calculating the predicted displacement of the joint surface of the next train-bridge coupling system numerical model and the test shock absorber according to the excitation load based on the train-bridge coupling system numerical model, and storing the predicted displacement at the moment i by adopting a memory;
step 4, compensating the prejudgment index psi based on the dynamic characteristicscWhether or not power characteristic compensation is required is determined. If the index psi is predeterminedc≤[ψc]Wherein [ psic]In order to allow the time axis error damping ratio, the influence of a loading error can be ignored, dynamic characteristic compensation is not needed, and the predicted displacement of the test shock absorber is directly used as a command displacement so as to simplify the test process; on the contrary, according to the predicted displacement of the test shock absorber, the nonlinear least square extrapolation compensation method provided by the invention is adopted as a dynamic characteristic compensation method to reduce the phase error and the amplitude error generated by a loading system, so that the command displacement of the test shock absorber can be obtained, and a memory is adopted to store the command at the moment;
step 5, transmitting the command displacement of the test shock absorber by the data interaction system, taking the command displacement of the test shock absorber as a target displacement, and feeding the target displacement serving as a control signal back to the loading system through the real-time simulation computing system to drive the hydraulic servo actuator to physically load a test piece of the test shock absorber;
step 6, measuring the actual measurement displacement and the actual measurement counter force of the test shock absorber through a displacement sensor and a force sensor, acquiring the actual measurement counter force of the test shock absorber through a data acquisition system, then feeding the actual measurement counter force back to a train-bridge coupling system numerical model through a real-time simulation calculation system based on a data interaction system, calculating the corresponding train-bridge coupling system motion response according to the actual measurement counter force of the test shock absorber and the load excitation of the (i + 1) th step based on the train-bridge coupling system numerical model, determining the predicted displacement of the joint of the train-bridge coupling system numerical model and the test shock absorber at the next step according to the train-bridge coupling system motion response, and storing the predicted displacement at the moment by adopting a memory;
and 7, repeating the fourth step to the sixth step until the test is finished by making i equal to i + 1.
8, for the test processes from the step 3 to the step 7, adopting an energy-based test stability on-line monitoring index to monitor the test stability on line in real time; if the monitoring index value is negative, namely the response of the system is unbounded, the test is unstable, and the test is directly ended.
The loading system described in this embodiment adopts an electro-hydraulic servo loading system (such as an MTS test system, a fuyun wing loading system, a midaircraft test loading system, etc.), and includes: the device comprises an upper computer, a controller, a hydraulic servo actuator and the like; the real-time simulation computing system comprises a DSpace system, an xPC target machine, an industrial personal computer, an NI controller system and the like.
In step 8 of this embodiment, the energy-based test stability on-line monitoring index E provided by the present invention is adoptediThe formula is as follows
Ei＝En+Ep
Wherein E isiThe energy dissipated by the whole system is an index for evaluating the stability of the system; enIs a column ofEnergy dissipated by the numerical model of the train-bridge coupling system is usually trapezoidal integral of the damping force of the numerical model of the train-bridge coupling system acting on the prediction displacement and hysteretic energy consumption of the numerical model of the train-bridge coupling system; epThe energy dissipated by the equivalent test piece is obtained by trapezoidal integration of the work done by the actual measurement counter force on the prediction displacement; f. ofn,iDamping force of the numerical model part of the ith train-bridge coupling system; f. ofe,iTesting the actually measured reaction force of the shock absorber part in the ith step; x is a radical of a fluorine atomiAnd q is the predicted displacement of the ith step and the total test step number respectively.
Further, on the basis of the step 4 dynamic characteristic compensation method, in order to further reduce the influence of loading errors, the method can be adopted
Correcting the measured reaction force in the ith step by a formula to obtain a measured reaction force correction value; and replacing the actual measurement reaction force in the ith step with an actual measurement reaction force correction value, and feeding back the actual measurement reaction force correction value to the numerical model of the train-bridge coupling system (the actual measurement reaction force correction value substitutes the damping force u generated by the vibration damper in the motion equation of the train-bridge coupling system) until the test is finished. Wherein the content of the first and second substances,
fe,irespectively obtaining an actual measurement reaction force correction value and an actual measurement reaction force of the shock absorber in the step i; c. CeTesting the damping of the shock absorber; k is a radical of formulaeTo test the stiffness of the shock absorber; x is the number ofi、xe,i、
And
the predicted displacement, the actual displacement, the predicted speed and the actual measurement speed of the shock absorber in the step i are respectively.
That is, in the above-described method, the measured reaction force is fed back to the train-bridge coupling system numerical model in step S6, and the measured reaction force correction value is fed back to the train-bridge coupling system numerical model in this case.
The drawings in the present specification are schematic views to assist in explaining the concept of the present invention, and schematically show the shapes of respective portions and their mutual relationships. Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention as claimed in the appended claims.
Claims (10)
1. A high speed train shock absorber testing system, comprising:
the real-time simulation computing system is used for computing the numerical model response in real time, judging whether dynamic characteristic compensation is needed or not according to the dynamic characteristic of the test shock absorber, and directly taking the predicted displacement of the test shock absorber as command displacement if the dynamic characteristic compensation is not needed; otherwise, reducing the loading error generated by the loading system 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 enables the shock absorber to realize dynamic command displacement through the driving actuator;
the data acquisition system is used for acquiring the actual displacement and the counterforce of the shock absorber;
and the data interaction system is used for realizing the communication between the real-time simulation computing system and the loading system.
2. A test method for a shock absorber of a high-speed train is characterized by comprising the following steps:
s1, dividing an object system comprising the shock absorber into a physical test piece part and a numerical model part; the object system is a test object system comprising a high-speed train;
the physical test piece is a shock absorber and is marked as a test shock absorber; the numerical model is a numerical model corresponding to the rest part except the shock absorber in the test object system and is recorded as an object numerical model;
s2, mounting the test shock absorber on a test bed for loading, compiling and downloading the numerical model to a real-time control board card 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 is equal to 1, calculating the predicted displacement of the interface between the next target numerical model and the test shock absorber according to the load action in the target numerical model based on the target numerical model, and storing the predicted displacement at the moment i by adopting a memory;
s4, judging whether dynamic characteristic compensation is needed according to the dynamic characteristics of the test shock absorber, and directly taking the predicted displacement of the test shock absorber as a command displacement if the dynamic characteristic compensation is not needed; otherwise, reducing the loading error generated by the loading system by a dynamic characteristic compensation method according to the predicted displacement of the test shock absorber so as to obtain the command displacement of the test shock absorber; storing the command displacement at the moment by adopting a memory;
s5, transmitting the command displacement of the test shock absorber by the data interaction system, taking the command displacement of the test shock absorber as a target displacement, sending the target displacement as a control signal to a loading system through the real-time simulation computing system, and driving the hydraulic servo actuator to physically load the test shock absorber;
s6, measuring the actual measurement displacement and the actual measurement counter force of the test shock absorber through the displacement sensor and the force sensor, collecting the actual measurement counter force of the test shock absorber through the data acquisition system, and then feeding the actual measurement counter force 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, calculating the motion response of a corresponding object system according to the actually measured counter force of the test shock absorber and the load action of the (i + 1) th step in the object numerical model, determining the predicted displacement of the interface of the next step object numerical model and the test shock absorber according to the motion response, and storing the predicted displacement at the moment by adopting a memory so as to complete data transmission and updating;
s7, i is made to i +1, and S4 to S6 are repeated until the end of the test.
3. The method for testing the shock absorber of the high-speed train according to claim 2, wherein in the process that the real-time simulation computing system feeds back the actual measurement reaction force to the object numerical model based on the data interaction system, the actual measurement reaction force is replaced by an actual measurement reaction force correction value, and then the actual measurement reaction force correction value is fed back to the object numerical model;
the actual measurement reaction correction value calculation formula is as follows:
wherein the content of the first and second substances,
fe,irespectively obtaining an actual measurement counter force correction value and an actual measurement counter force of the shock absorber in the step i; c. CeTesting the damping of the shock absorber; k is a radical of formulaeTo test the stiffness of the shock absorber; x is a radical of a fluorine atomi、xe,i、
And
the predicted displacement, the actual displacement, the predicted speed and the actual measurement speed of the shock absorber in the step i are respectively.
4. The method for testing the shock absorber of the high-speed train as claimed in claim 2 or 3, wherein the method further comprises the step of monitoring the test stability on line in real time, namely, for the test process from S3 to S7, the test stability is monitored on line in real time by adopting an energy-based test stability on-line monitoring index.
5. The method for testing the shock absorber of the high-speed train as claimed in claim 4, wherein the on-line monitoring indexes of the test stability based on energy are as follows:
Ei＝En+Ep
wherein, EiThe energy dissipated by the whole system is an index for evaluating the stability of the system; enEnergy dissipated for the object numerical model, trapezoidal integral of the damping force of the object numerical model acting on the prediction displacement and hysteretic energy consumption of the object numerical model; epThe energy dissipated by the equivalent test piece is obtained by trapezoidal integration of actually measured counter force acting on the predicted displacement, and the equivalent test piece is a virtual test piece with mechanical properties meeting the relation of the actual force and the predicted displacement; f. ofn,iThe damping force of the object numerical model part in the ith step; f. ofe,iTesting the actually measured reaction force of the shock absorber part in the ith step; x is a radical of a fluorine atomiAnd q are the predicted displacement of the ith step and the total number of test steps respectively.
6. The method for testing the shock absorber of the high-speed train as claimed in claim 5, wherein in the process of monitoring the stability of the test on line in real time by using the on-line monitoring index for the stability of the test based on energy, if the monitoring index E isiIf positive, the structural response will be bounded and the system will stabilize; if monitoring the index EiIf the response is negative, i.e. the response of the system will be unbounded, the test is unstable, and the test is ended directly.
7. The method for testing the shock absorber of the high-speed train according to claim 6, wherein in the process of judging whether dynamic characteristic compensation is required according to the dynamic characteristics of the test shock absorber in S4, a time axis error damping ratio psi is adoptedcAs a dynamic characteristic compensation prejudgmentIndex, if the index psi is predeterminedc≤[ψc]Wherein [ psic]If the time axis error damping ratio is allowed, dynamic characteristic compensation is not needed, otherwise, the dynamic characteristic compensation is needed;
the time axis error damping ratio is as follows:
wherein, tau is the time error corresponding to the phase error, and omega is the snaking vibration circle frequency of the system.
8. The test method for the shock absorber of the high-speed train according to claim 7, wherein when the dynamic characteristic compensation is required, a nonlinear least square extrapolation compensation method is adopted as the dynamic characteristic compensation method.
9. The method for testing the shock absorber of the high-speed train according to claim 8, wherein the object system is a high-speed train system; the object numerical model is a vehicle body numerical model;
the numerical model of the train body is embodied in the form of a motion equation, and the motion equation of the high-speed train is as follows:
wherein M, C and K are the mass, damping and stiffness matrices of the train system, respectively; x is a displacement vector of the respective degree of freedom,
is the first derivative of X and is,
is the second derivative of X; u is the damping force vector generated by the test shock absorber; w is a linear or non-linear wheel-rail contact force with the wheelRail models, rail irregularities, etc.; luAnd lwIs a coefficient matrix which is respectively related to the installation of the test shock absorber, the irregularity of the track and the like; f is a wind load vector borne by the train running at high speed;
in S6, the motion response of the corresponding object system is calculated according to the actual measurement reaction force of the test damper and the load action at step i +1 in the object numerical model, that is, the vehicle motion response is calculated according to the actual measurement reaction force of the test damper and the track irregularity action at step i +1 in the vehicle body numerical model and the wind load excitation.
10. The method for testing the shock absorber of the high-speed train as claimed in claim 8, wherein 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 consists of a high-speed train subsystem and a bridge subsystem, and the motion equation is as follows:
wherein M isv、CvRespectively the train subsystem mass and the damping; mb、CbRespectively the total mass and the total damping matrix of the bridge subsystem; k issystem＝K1+K2Is the global stiffness matrix of the system, where K1The overall rigidity matrix of the coupling terms is not considered for the vehicle subsystem and the bridge subsystem; k2A contact matrix of the vehicle and the track; fvAnd FbRespectively are external force load vectors borne by the train subsystem and the bridge subsystem; xv，
And Xb，
Are train subsystems respectivelyAnd displacement, velocity, acceleration vectors of the bridge subsystem; r is an actually measured reaction force vector of the test shock absorber;
in S6, a motion response of the corresponding object system is calculated according to the actual measurement reaction force of the test shock absorber and the action of the (i + 1) th step load in the object numerical model, that is, the corresponding motion response of the train-bridge coupling system is calculated according to the actual measurement reaction force of the test shock absorber and the excitation of the (i + 1) th step load.
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