A high-speed rail track vibration sound radiation efficient measurement method under mobile load

Abstract

The application discloses a kind of fine transient finite element-boundary element high-speed railway rail vibration sound radiation efficient measurement method under mobile load, belong to railway noise simulation, calculation method technical field, by establishing rail discrete support finite element-boundary element model, using APDL command stream method to calculate the transient response under different moving speed, excitation frequency under mobile excitation single-wheel excitation and mobile double-wheel coherent excitation, efficiently obtain the rail vibration response characteristics under mobile load, and calculate the rail transient sound radiation characteristics.The fine transient finite element-boundary element high-speed railway rail vibration sound radiation efficient measurement method under mobile load of the application uses the way of transient calculation command written in APDL language in finite element software ANSYS, and is combined with ACOUSTIC software, efficiently calculates the rail vibration sound radiation response of high-speed railway rail under mobile excitation, higher precision, faster calculation.

Description

Technical Field

[0001] This invention relates to a refined transient finite element-boundary element method for efficient measurement of acoustic radiation of high-speed railway rail vibration under moving loads, which is applied to the prediction of wheel-rail noise in high-speed railways and belongs to the technical field of railway noise simulation and calculation methods. Background Technology

[0002] The high-speed movement of trains on tracks generates complex rail dynamics problems. These problems involve initial and boundary value issues, as well as geometric and state nonlinearities. Furthermore, the computational efficiency of explicit and implicit dynamics for rail response under moving loads is currently low. Analytical algorithms using discrete support beam models are overly simplistic and fail to capture the vibration and acoustic radiation characteristics of medium- and high-frequency rail cross-sectional deformation modes.

[0003] Therefore, a refined transient finite element-boundary element method for measuring the vibration and acoustic radiation of high-speed railway rails under moving loads is provided. This method uses APDL language to write transient calculation commands in the finite element software ANSYS and combines them with ACOUSTIC software to efficiently calculate the vibration and acoustic radiation response of high-speed railway rails under moving excitation. The method has high accuracy and fast calculation speed. Summary of the Invention

[0004] The purpose of this invention is to provide a refined and efficient measurement method for acoustic radiation of high-speed railway rail vibration under moving loads using the transient finite element-boundary element method, to develop a refined and efficient calculation method, to construct a refined model of discrete support track for high-speed railway on straight sections, and to study an efficient calculation method for acoustic vibration under moving loads using the transient finite element-boundary element method.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution:

[0006] A refined transient finite element-boundary element method for efficient measurement of acoustic radiation from high-speed railway rail vibration under moving loads, comprising the following steps:

[0007] (1) Establish a finite element-boundary element model for discrete rail support;

[0008] (2) The APDL command flow method is used to calculate the transient response under different moving speeds and excitation frequencies under single-wheel excitation and coherent dual-wheel excitation of moving excitation;

[0009] (3) Time-frequency analysis method is used to analyze the spatial-wavenumber domain response characteristics of rail vibration, and the rail vibration response characteristics under moving load are obtained efficiently.

[0010] (4) Calculate the transient acoustic radiation characteristics of the rail.

[0011] Preferably, step (1) is as follows: a track slab model is established using solid185 elements in the finite element software ANSYS, a rail model is established using solid185 elements, and a constraint relationship is established between the rail and the track slab using spring elements at equal intervals.

[0012] Preferably, step (2) is as follows: using APDL command flow, compile automated commands, establish the load step action time according to the length of the supporting finite element-boundary element model and the relative motion speed of the wheel and rail, and calculate the motion excitation response under the action of two wheels and under the action of a single wheel.

[0013] Preferably, step (3) is as follows: the acceleration, velocity, displacement and other information of each model node obtained by the finite element model calculation in step 2 are automatically extracted by APDL, and the obtained data stream is imported into MATLAB for Fourier transform to obtain the frequency domain result.

[0014] Preferably, step (4) is as follows: the calculation results of the finite element model are transferred into the boundary element model, the boundary element model of the rail is established by using the envelope method, and the result of the surface node vibration being converted into sound radiation is calculated.

[0015] Beneficial effects: The refined transient finite element-boundary element method for measuring the vibration and acoustic radiation of high-speed railway rails under moving loads of the present invention adopts the method of writing transient calculation commands in the APDL language in the finite element software ANSYS, and combining it with ACOUSTIC software to efficiently calculate the vibration and acoustic radiation response of high-speed railway rails under moving excitation. It has high accuracy and fast calculation speed. Attached Figure Description

[0016] Figure 1 This is a flowchart of the refined transient finite element-boundary element method for efficient measurement of acoustic radiation of high-speed railway rail vibration under moving load, as described in Embodiment 1 of the present invention.

[0017] Figure 2 This is a schematic diagram of the rail grid in Embodiment 1 of the present invention.

[0018] Figure 3 This is a sound field distribution diagram in the horizontal space when a single wheel moves through the excitation of the present invention in Embodiment 1.

[0019] Figure 4 This is the sound pressure level response time history curve at the field point in Embodiment 1 of the present invention. Detailed Implementation

[0020] Unless otherwise specified, the components involved in the embodiments of the present invention are all conventional components in the art, the detection methods involved are all conventional detection methods in the art, and the software used is commonly used software in the art.

[0021] Example 1

[0022] like Figure 1 The diagram shows a flowchart of the efficient measurement method for high-speed railway rail vibration and acoustic radiation under moving load using a refined transient finite element-boundary element method according to Embodiment 1 of the present invention. The efficient measurement method for high-speed railway rail vibration and acoustic radiation under moving load using a refined transient finite element-boundary element method according to the present invention includes the following steps: First, based on the moving force model theory, a discrete support finite element-boundary element model of the rail is established; second, the rail response under moving excitation includes different excitation frequencies, different moving speeds, and coherent excitation by two wheels; finally, the transient acoustic radiation of the rail under moving excitation includes the sound field distribution and sound pressure level at field points in the horizontal space.

[0023] The present invention provides a refined transient finite element-boundary element method for efficient measurement of acoustic radiation from high-speed railway rail vibration under moving loads, comprising the following steps:

[0024] (1) Establish a discrete support finite element-boundary element model for the rail; use solid185 elements in the finite element software ANSYS to establish the track slab model and the rail model, and use spring elements at equal intervals to establish constraint relationships between the rail and the track slab.

[0025] Specifically as follows:

[0026] The track structure is symmetrical along the longitudinal direction, so half of it is used to build a finite element model. The track slab and sleeper support platform are considered as a whole, and the concrete base is regarded as a rigid foundation. The CA mortar layer is simulated to connect with the track slab using spring element COMBIN14. The track slab uses SOLID185 elements, and the 60kg / m rail on it also uses SOLID185 elements. The track slab and rail are connected by a periodically spaced fastener system, which is simulated by COMBIN14 elements in the finite element model. Then, a rail vibration-acoustic radiation boundary element model is built on the Virtual.lab Acoustics platform. The acoustic envelope mesh of the rail is generated based on the rail finite element model. The rail surface vibration velocity calculated in the finite element software is used as the boundary condition for acoustic calculation. The frequency response data of the rail vibration velocity is converted to the acoustic boundary element mesh, and the acoustic radiation characteristics of the rail are calculated using the direct boundary element method.

[0027] (2) The APDL command flow method is used to calculate the transient response under different moving speeds and excitation frequencies under single-wheel excitation and coherent dual-wheel excitation of moving excitation;

[0028] Specifically as follows:

[0029] Using APDL command flow, automated commands are compiled. Based on the length of the supporting finite element-boundary element model and the relative speed of wheel-rail motion, the load step application time is established, and the movement excitation response under two-wheel action and single-wheel action is calculated.

[0030] (3) The time-frequency analysis method is used to analyze the spatial-wavenumber domain response characteristics of rail vibration, efficiently obtain the rail vibration response characteristics under moving load, and calculate the transient acoustic radiation characteristics of rail.

[0031] Specifically as follows:

[0032] The acceleration, velocity, displacement and other information of each model node obtained from the finite element model calculation in step 2 are automatically extracted by APDL. The obtained data stream is imported into MATLAB for Fourier transform to obtain the frequency domain results.

[0033] (4) Calculate the transient acoustic radiation characteristics of the rail;

[0034] Specifically, the calculation results of the finite element model are transferred into the boundary element model. The boundary element model of the rail is established using the envelope method, and the results of the surface nodal vibration being converted into sound radiation are calculated.

[0035] The following is a detailed explanation with reference to the accompanying drawings:

[0036] In the acoustic boundary element software Virtual.lab Acoustic, the transient boundary element (BEM) method is used to interpolate and transfer the nodal vibration results of the finite element model from the transient time-series calculation in ANSYS to the acoustic boundary element model. The acoustic radiation of the rail under single-frequency moving force sequence excitation in a free acoustic field environment is calculated and analyzed. The time history response characteristics are obtained by solving in the time domain. The vibration response results under a 500Hz single-wheel moving harmonic force excitation are used for transient boundary element calculation (rail with a single moving force of 83.4kN at a speed of 300km / h, 500Hz, and a rail length of 6.5m). The transient boundary element mesh of the rail is obtained. Figure 2 As shown;

[0037] The transient boundary element method was used to calculate the sound pressure level distribution in the horizontal plane above the rail top using a finite element model of a rail subjected to harmonic force excitation by a single wheel. Field points were set at distances of 5m and 25m from the rail top within the horizontal plane, and the sound pressure level response at these field points was analyzed. Figure 3 The image shows the sound field distribution in the horizontal space when a single wheel moves and passes through the area according to Embodiment 1 of the present invention (a cloud map showing the sound pressure level distribution in the horizontal space at 0.1s). Figure 3It can be seen that when the rail is excited by a moving force of 300 km / h, the total excitation time is 0.078s. At 0.1s, the sound field distribution shows that in the area closer to the rail, the sound pressure level decreases slightly because there is no longer any excitation force. In the other areas, the sound pressure level decreases as the distance from the rail increases, and the distribution on the horizontal plane is relatively uniform.

[0038] like Figure 4 The figure shows the sound pressure level response time history curve at the field point in Embodiment 1 of the present invention; Figure 4 It can be seen that, since the speed of sound in air is 340 m / s, the sound pressure level response is generated at the 5 m point 0.016 s after the rail is excited, and at the 25 m point 0.080 s after the rail is excited. The sound pressure level at the point fluctuates within a certain range and is relatively stable within a certain period (e.g., 100 ms). Taking the stable time period of the two points (0.02-0.03 s at 5 m and 0.084-0.094 s at 5 m), the average sound pressure levels are calculated to be 75.21 dB at 5 m and 54.25 dB at 25 m.

[0039] When a train runs on a track, each moving wheel exerts a structural force on the rail. These structural forces can be viewed as a group of moving forces distributed according to the axle spacing of the vehicle. The physical process of the high-speed wheels moving on the rail can be simplified as the vibration process of a discretely supported elastic beam subjected to moving loads and subjected to broadband random excitation. The high-speed movement of the wheel-rail excitation point causes the vibration of the previous excitation point and its vicinity to not be completely attenuated, and vibration is generated and superimposed at the next excitation point and its vicinity. At the same time, the rail guided waves such as bending waves are excited and transmitted and accumulated along the rail, which interact with each other. Compared with the rail vibration characteristics under low speed or static excitation, they change significantly.

[0040] The calculation and simulation of high-speed railway wheel-rail noise requires understanding the vibration and sound radiation characteristics of the rail. When a train runs at high speed on the rail, the interaction between the wheel and the rail under the surface roughness of their respective surfaces can be regarded as a random vibration process that cannot be described by a deterministic function but has certain statistical regularities. At the same time, it has narrow-band spike characteristics and broadband characteristics under peak wavelength excitation.

[0041] This invention addresses the acoustic and vibration characteristics of rails under the action of a wide-frequency moving force group in multi-axle trains. It utilizes a fusion of finite element transient analysis and transient boundary element analysis to decompose the wide-frequency characteristics of the moving load, calculates the acoustic and vibration characteristics of the rails under multiple single-frequency harmonic excitations in the time and space domains, and uses fast Fourier transform to obtain frequency domain-wavenumber domain results to calculate the acoustic and vibration characteristics of the rails under moving harmonic excitations.

[0042] In addition, the four wheels of the two axles of a bogie are distributed on both sides of the rails on both sides of the track. The wheels on both sides are rigidly connected by the axles. The two rails on the same track are connected by the track slab or sleeper. There are coupling correlations between the two rails on the same track, the two wheels on the same axle, and the two wheels on the same side rail. The acoustic and vibration characteristics of the rails under coherent harmonic motion excitation are also the subject of this calculation method.

[0043] This invention presents a refined transient finite element-boundary element method for efficient measurement of high-speed railway rail vibration and acoustic radiation under moving loads. By establishing a discrete support finite element-boundary element model of the rail and employing the APDL command flow method, it calculates the transient response under different moving speeds and excitation frequencies under moving excitation with single-wheel excitation and coherent moving dual-wheel excitation. This efficiently obtains the rail vibration response characteristics under moving loads and calculates the transient acoustic radiation characteristics of the rail. This provides an efficient calculation method for studying the vibration and acoustic radiation characteristics of rails under moving excitation in high-speed railway wheel-rail noise.

[0044] This invention presents a refined transient finite element-boundary element method for efficient measurement of acoustic radiation of high-speed railway rail vibration under moving loads. It develops a refined and efficient calculation method, constructs a refined model of discrete support track of high-speed railway on straight sections, and studies an efficient calculation method for acoustic vibration of transient finite element-boundary element under moving loads.

Claims

1. A high-speed railway rail vibration sound radiation efficient measurement method under moving load, comprising the following steps: (1) establishing a rail discrete support finite element-boundary element model; (2) using an APDL command stream method, calculating transient responses under different moving speeds and excitation frequencies under moving excitation single-wheel excitation and moving double-wheel coherent excitation; (3) using a time-frequency analysis method, analyzing spatial-wave number domain response characteristics of rail vibration, and obtaining rail vibration response characteristics under moving load; (4) calculating rail transient sound radiation characteristics. The step (1) is specifically as follows: using a solid185 element in a finite element software ANSYS to establish a track plate model, using a solid185 element to establish a rail model, and using a spring element to establish a constraint relationship at equal intervals between the rail and the track plate; The step (2) is specifically as follows: using an APDL command stream, preparing an automatic command, establishing a load step action time according to a length of the support finite element-boundary element model and a wheel-rail relative motion speed, and calculating moving excitation responses under two-wheel action and single-wheel action; The step (3) is specifically as follows: using APDL to automatically extract acceleration, speed and displacement information of each model node calculated by the finite element model in the step 2, importing the obtained data stream into MATLAB to perform Fourier transform, and obtaining frequency domain results; The step (4) is specifically as follows: converting the finite element model calculation results into the boundary element model, using an envelope method to establish a boundary element model of the rail, and calculating results of sound radiation converted from surface node vibration.

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