CN115935733A - A Simulation and Prediction Method of Decoupling Membrane-Channel Plate Impact Noise of Liquid Resistance Mount - Google Patents

Abstract

The invention discloses a simulation prediction method for the impact noise of a liquid resistance mount decoupling membrane, comprising: obtaining a three-dimensional structure model of a target liquid resistance mount; establishing a dynamic simulation model of a decoupling membrane-flow channel plate, and performing dynamic simulation, Simulate the collision process of the decoupling membrane and the runner plate, and calculate the vibration response of the runner plate; based on the dynamic simulation model, establish the acoustic boundary element simulation model of the decoupling membrane-runner plate; according to the vibration response, perform collision impact on the runner plate Noise source processing and radiated noise calculation to obtain the noise spectrum simulation results; predict the impact noise level of the liquid resistance mount and whether there is any abnormal sound problem based on the noise analysis results. The present invention predicts whether there is abnormal noise in the liquid resistance mount based on acoustic simulation, effectively reduces the number of experiments, and provides a reference for the design of the liquid resistance mount structure; uses a simplified decoupling membrane-flow channel plate model to ensure the accuracy of the simulation Under the premise of greatly shortening the calculation time, it is convenient for batch simulation to optimize the structure.

Description

A Simulation Prediction Method of Decoupling Membrane-Channel Plate Impact Noise of Liquid Resistance Mount

technical field

The invention relates to the field of noise analysis of liquid resistance mounts of automobile powertrains, in particular to a simulation prediction method of liquid resistance mount decoupling membrane-flow channel plate impact noise.

Background technique

As an engine vibration damping component, the liquid resistance mount has relatively ideal dynamic characteristics. It adopts an inertial channel-decoupling membrane structure inside, so that the liquid resistance mount has large damping characteristics at low frequencies and low stiffness characteristics at high frequencies. However, the complex structure also brings noise problems to the liquid resistance mount. The noise of the liquid resistance mount is divided into impact noise and cavitation noise. The cavitation noise is because the liquid in the liquid resistance mount vaporizes at low pressure and explodes under pressure at high pressure. To generate shock waves, in order to avoid cavitation noise, known effective methods include adding pressure relief valves and setting bypass channels. Impact noise is the noise generated when the decoupling membrane floats up and down and hits the runner plate when the suspension is working. This noise is more obvious under low-frequency and high-amplitude conditions. In the real vehicle, when the vehicle passes through a bad road at low speed, the cab feels obvious abnormality. ring. The structure of the liquid resistance mount itself determines that the impact process will inevitably occur during its operation. It is of great significance to study the generation mechanism and prediction method of the impact noise to solve the problem of abnormal noise.

The noise generated by the collision and impact of the decoupling membrane and the flow channel plate can be divided into two stages: acceleration noise and self-sounding noise. Noise; self-sounding noise corresponds to the free attenuation vibration stage, the surface acceleration of the object is gradually attenuated, and the noise radiation is also gradually reduced.

When studying the problem of abnormal noise of liquid resistance mounts through experiments, the test methods include: 1) Use a microphone to directly measure the sound pressure signal, and use the peak value of the sound pressure level to evaluate the noise level; 2) Use a force sensor to measure the support reaction force at the fixed end of the liquid resistance mount The signal is removed by high-pass filtering to remove the excitation force received by the liquid resistance mount, and the force signal generated by the decoupling membrane-flow channel plate collision impact can be obtained, and the peak value of the signal is taken as the noise evaluation standard. The experimental method requires the actual parts of the liquid resistance mount, and the noise of the liquid resistance mount cannot be predicted at the early stage of design, and it is not convenient to optimize the part structure, but the experimental test can be used to verify the accuracy of the simulation method.

In the prior art, the simulation prediction methods for the abnormal noise of the liquid resistance mount include: 1) Perform fluid-solid coupling finite element simulation on the liquid resistance mount to solve the change of the slapping force of the decoupling membrane over time, and calculate the peak value of the slapping force As the basis for judging abnormal noise, this method needs to model the whole liquid resistance mount, and the fluid-solid coupling effect is taken into account, resulting in a more complex model; 2) Solve the relationship curve between the contact force and equivalent displacement between the decoupling membrane and the flow channel plate by simulation , and use the maximum contact stiffness to evaluate the impact noise of the decoupling membrane. If the maximum contact stiffness exceeds 300N/mm, it is judged that there is an abnormal noise problem. Angle analysis of abnormal noise problem.

Contents of the invention

In order to solve the problems existing in the prior art, the present invention proposes a simulation prediction method for the impact noise of the decoupling membrane of the liquid resistance mount. The method analyzes the impact noise from the acoustic point of view, and can quickly and accurately predict the Analyzing and predicting abnormal noise conditions.

In order to achieve the purpose of the present invention, the present invention provides a simulation prediction method for the impact noise of the decoupling membrane of the fluid resistance mount, which includes the following steps:

10. Obtain the three-dimensional structure model of the target hydraulic mount;

2○. Extract the decoupling membrane-flow channel plate assembly model from the three-dimensional structure model of the target liquid resistance suspension, draw grids for the assembly model, assign material properties, add constraints and loads, establish a dynamic simulation model, and perform instantaneous Dynamic finite element simulation;

30. Calculate the collision impact response of the decoupling membrane-runner plate, and obtain the vibration acceleration information of the runner plate surface;

40. According to the dynamic simulation model, define the acoustic boundary conditions and the sound source surface, set the acoustic field points to be analyzed, and establish the decoupling membrane-flow channel plate acoustic boundary element simulation model;

5○. Load the vibration acceleration information as the sound source into the decoupling membrane-runner plate acoustic boundary element simulation model, and calculate the sound pressure level distribution of the external field points in the decoupling membrane-runner plate model;

○6. Perform acoustic boundary element analysis to obtain the sound pressure level versus frequency curve of the acoustic field point, use the maximum value of the sound pressure level as the evaluation standard for abnormal noise, and compare it with the abnormal noise threshold to predict whether there is abnormal noise in the liquid resistance mount question.

Further, in step ○2, in the dynamic simulation model, the flow channel plate is fixed, and the pressure applied on the surface of the decoupling membrane is used as model input.

Further, in step ②, when it is a floating decoupling membrane liquid resistance suspension, the initial position of the decoupling membrane in the dynamic simulation model is in the middle of the flow channel liquid chamber, and when it is a semi-floating decoupling membrane liquid resistance suspension When placed, the total thickness of the decoupling membrane is greater than the height of the flow channel air chamber, and the assembled decoupling membrane is in a compressed state.

Further, in step ②, the following sub-steps are included:

Extract the decoupling membrane-flow channel plate assembly model;

Import the decoupling membrane-flow channel plate assembly model into the finite element pre-processing software for mesh division;

Import the meshed decoupling membrane-flow channel plate assembly model into the finite element analysis software, then set the material properties of the decoupling membrane and the flow channel plate respectively, apply model constraints and loads, and place the flow channel plate The lower surface is fixed, and pressure is applied to the surface of the decoupling membrane, and the surface vibration acceleration of the decoupling membrane and the flow channel plate at the moment of collision between the decoupling membrane and the flow channel plate is simulated and analyzed.

Further, the finite element pre-processing software uses HyperMesh software, and the finite element analysis software uses Abaqus.

Further, in step ③, the time-domain response of the vibration acceleration on the surface of the runner plate is calculated as the excitation of the acoustic simulation.

Further, in the decoupling membrane-flow channel plate acoustic boundary element simulation model in step ④, the surface of the flow channel plate is selected as the sound source surface.

Further, the vibration acceleration information in step ⑤ is converted into a frequency domain signal by Fourier transform, and then used as an acoustic simulation excitation input.

Further, in step ⑤, the sound pressure calculation formula of the acoustic field point is

p＝{A _TV (ω)} ^T {a _n (ω)}

In the formula, p is the sound pressure of the acoustic field point; A _TV is the acoustic transfer vector of the structure surface node to the acoustic field point; a _n is the normal vibration acceleration of the structure surface; ω is the angular velocity, and T is the transposition.

Further, after step ⑥, step ⑦ is also included: if the analysis determines that there is an abnormal sound problem, optimize the structure of the decoupling membrane-flow channel plate, and repeat steps ① to ⑥ until the sound pressure signal meets the requirements, wherein, from The thickness of the decoupling membrane, the height of the noise reduction rib and the gap between the decoupling membrane and the flow channel plate are optimized.

Abnormal sound threshold in step ⑥: It is obtained through simulation analysis and experimental test summary of different types of liquid resistance mounts and decoupling membrane-flow channel plates with different structures. The abnormal sound threshold is between "no abnormal sound problem" Between the maximum simulated sound pressure" and the "minimum simulated sound pressure with abnormal noise problem", the range can be continuously narrowed by increasing the data to make the value more accurate.

Structural optimization in step ⑦: the optimization object is generally a decoupling membrane structure. Commonly used noise reduction methods include adding noise reduction ribs and using a semi-floating decoupling membrane structure. Structural optimization generally considers three design parameters of the decoupling membrane, Including the thickness of the decoupling membrane, the height of the noise reduction rib and the gap between the decoupling membrane and the flow channel plate, the optimal values of the parameters can be analyzed from these three aspects, so as to obtain a better noise reduction effect; the decoupling membrane and the flow channel The smaller the plate gap, the lower the noise, but at the same time, it should be considered that the stiffness of the liquid resistance mount increases due to the reduction of the gap; the decoupling membrane thickness and the height of the noise reduction rib are generally designed within a specific range, and the noise is small.

Compared with the prior art, the present invention has at least the following beneficial effects:

1) The present invention analyzes the impact noise of the fluid-resistance mount decoupling membrane based on the theory of impact acoustics, and can predict whether there is abnormal noise in the fluid-resistance mount through the simulation method, effectively reducing the number of experiments, and providing reference for the design of the fluid-resistance mount structure in accordance with;

2) The liquid resistance mount structure is relatively complex, but the parts that collide are the decoupling membrane and the flow channel plate, so the present invention can only analyze the decoupling film-flow channel plate model, and can accurately predict the liquid resistance mount Under the premise of impact noise, the calculation time is greatly shortened, and it is convenient to optimize the structure through batch simulation;

3) The present invention can predict and analyze different types of liquid resistance mounts, and is also applicable to the situation where the decoupling membrane is a floating and semi-floating structure. The proposed abnormal sound threshold can be used as a unified standard.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only For some embodiments of the invention, those of ordinary skill in the art can also obtain other drawings based on these drawings without creative work, wherein:

Fig. 1 is a flow chart of the steps of a method for simulation and prediction of impact noise of fluid resistance mount decoupling membrane-flow channel plate provided by an embodiment of the present invention.

Fig. 2 is a finite element model diagram of the decoupling membrane-flow channel plate in the embodiment of the present invention.

Fig. 3 is a nephogram of the external sound pressure level of the acoustic simulation in the embodiment of the present invention.

Fig. 4 is a spectrum diagram of the simulated sound pressure of the fluid resistance mount (1) in the embodiment of the present invention when different decoupling membrane structures are used.

Fig. 5 is a spectrum diagram of the simulated sound pressure of the liquid resistance mount (2) in the embodiment of the present invention when using different decoupling membrane structures.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts are within the protection scope of the present invention.

As shown in Fig. 1, a method for simulation and prediction of impact noise of liquid resistance mount decoupling membrane provided by the present invention includes the following steps:

Step 1. Obtain the three-dimensional structure model of the target hydraulic mount.

Step 2. Extract the decoupling membrane-flow channel plate assembly model from the three-dimensional structural model of the target liquid resistance suspension, draw a grid for the assembly model, assign material properties, add constraints and loads, establish a dynamic simulation model, and carry out Transient finite element simulation.

In some embodiments of the present invention, there are upper and lower flow channel plates in the liquid resistance suspension, and the lower flow channel plate and the base of the liquid resistance suspension are designed as a whole. contact part. Import the decoupling membrane-flow channel plate assembly model into the HyperMesh software, set the decoupling membrane as a hexahedral grid, the flow channel plate as a tetrahedral grid, and the grid size as 1mm (in other embodiments, it can be set to other values ), meshing the decoupled membrane-flow channel plate assembly model.

Import the meshed decoupling membrane-flow channel plate assembly model into the finite element analysis software, then set the material properties of the decoupling membrane and the flow channel plate respectively, apply model constraints and loads, and place the flow channel plate The lower surface is fixed, and pressure is applied to the surface of the decoupling membrane. Since there is a certain gap between the decoupling membrane and the flow channel plate initially, the two collide under excitation. The surface vibration acceleration of the decoupling membrane and the flow channel plate at the moment of the collision is simulated and analyzed Condition.

In some embodiments of the present invention, the flow channel plate material is defined as metal aluminum with a density of 2700kg/m ³ , Young’s modulus of 72500MPa, and Poisson’s ratio of 0.33; the decoupling membrane material is rubber with a density of 1100kg /m ³ , using the Mooney-Rivlin hyperelastic constitutive model, the parameters are: C ₁₀ =0.2897MPa, C ₀₁ =0.0599MPa. Simulate the impact process between the decoupling membrane and the flow channel plate, constrain the degrees of freedom of the lower surface of the flow channel plate in six directions, and apply pressure to the surface of the decoupling membrane as an excitation to perform transient finite element simulation. The above specific numerical value is only a specific example, and in other embodiments, other numerical values can also be set.

In some embodiments of the present invention, the finite element analysis software used is Abaqus.

In some embodiments of the present invention, a pressure of 0.1 MPa is applied to the upper surface of the decoupling membrane. Of course, it can be understood that in other embodiments, the magnitude of the applied pressure can be set to other values.

In some embodiments of the present invention, the simulation duration is set to 10ms in this step. Of course, it can be understood that in other embodiments, the simulation duration can be set to other values.

In some embodiments of the present invention, the dynamic simulation model: for a floating decoupling membrane liquid resistance suspension, the initial position of the decoupling membrane is in the middle of the flow channel liquid chamber; for a semi-floating decoupling membrane liquid The total thickness of the decoupling membrane is greater than the height of the flow channel air chamber, and the assembled decoupling membrane is in a compressed state. After obtaining the decoupling membrane-runner plate model, it is necessary to perform pre-compression simulation processing on the decoupling membrane.

Step 3. Submit an analysis task in the finite element analysis software, calculate the collision impact response of the decoupling membrane-runner plate, and obtain the vibration acceleration information of the runner plate surface.

Step 4. According to the dynamic simulation model, define the acoustic boundary conditions and the sound source surface, set the acoustic field points to be analyzed, and establish the decoupling membrane-flow channel plate acoustic boundary element simulation model.

In some of the embodiments of the present invention, the finite element analysis result file obtained in step 3 is imported into LMSVirtual.Lab, and according to the dynamic simulation model, the outer surface of the runner plate is set as the sound source surface, and the propagation medium is defined as air , select the point 1m away from the center of the dynamic simulation model on the Y axis as the acoustic field point, and establish the acoustic boundary element simulation model of the decoupling membrane-runner plate.

Step 5. Load the vibration acceleration information as a sound source into the decoupled membrane-runner plate acoustic boundary element simulation model, and calculate the sound pressure level distribution of the external field points in the decoupled membrane-runner plate model.

In some embodiments of the present invention, Fourier transform is performed on the vibration acceleration time domain signal obtained by dynamic simulation, and loaded into the decoupling membrane-flow channel plate acoustic boundary element simulation model as an excitation source, and the frequency range for solution is set From 40Hz to 2000Hz, with an interval of 40Hz, simulate and analyze the distribution of sound pressure level in the external field.

Among them, the sound pressure of the acoustic field point is calculated according to the formula p={A _TV (ω)} ^T {a _n (ω)}, where: p is the sound pressure of the acoustic field point; A _TV (Acousic Transfer Vector) is the structure The sound transfer vector of the surface node to the acoustic field point can be determined by the shape of the sound source structure, the location of the field point, the properties of the sound transfer medium, and the analysis frequency, etc., and is an inherent property of the system; a _n is the normal vibration acceleration of the structure surface; superscript T is the transpose, ω is the angular velocity, which means that the formula is solved in the frequency domain, and the acceleration signal obtained from the dynamics simulation is a time domain signal, so it should be transformed into a frequency domain signal by Fourier transform before input.

Step 6. The curve of the sound pressure level at the site point changing with the frequency is obtained by simulation, and the maximum value of the sound pressure level, that is, the peak value of the sound pressure level, is used as the evaluation standard of the abnormal sound degree, and compared with the abnormal sound threshold value, the impact noise of the liquid resistance mount is predicted.

The abnormal sound threshold is determined by simulation and experiment of decoupling membrane-flow channel plate with various structures. In some embodiments of the present invention, the abnormal sound threshold is determined to be 57dB. If the peak value of the sound pressure level obtained by simulation exceeds the abnormal sound threshold, it is determined that the liquid resistance mount has an abnormal sound problem; otherwise, it is considered that the liquid resistance mount is noisy. within an acceptable range. In other embodiments, the abnormal sound threshold may also adopt a numerical value.

The embodiment of the present invention provides a simulation prediction method for the impact noise of the decoupling membrane of the liquid resistance mount, which can determine the degree of abnormal noise of the liquid resistance mount through simulation analysis, and this method uses a simplified decoupling membrane-flow channel plate The model is suitable for batch simulation of different structures, and realizes the optimization of decoupling membrane-flow channel plate structure. And it can predict and analyze different types of liquid resistance mounts, and it is also applicable to the situation where the decoupling membrane is a floating and semi-floating structure.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A simulation prediction method for impact noise of a liquid resistance suspension decoupling film is characterized by comprising the following steps:

(1) acquiring a target liquid resistance suspension three-dimensional structure model;

(2) extracting a decoupling film-runner plate assembly model from the target liquid resistance suspension three-dimensional structure model, drawing a grid on the assembly model, endowing material properties, adding constraint conditions and loads, establishing a dynamic simulation model, and performing transient finite element simulation;

(3) calculating the collision impact response of the decoupling film and the runner plate, and acquiring the vibration acceleration information of the surface of the runner plate;

(4) defining an acoustic boundary condition and a sound source surface according to the dynamic simulation model, setting an acoustic field point to be analyzed, and establishing a decoupling film-flow channel plate acoustic boundary element simulation model;

(5) loading vibration acceleration information serving as a sound source into the decoupling film-flow channel plate acoustic boundary element simulation model, and calculating the sound pressure level distribution condition of external field points in the decoupling film-flow channel plate model;

(6) and performing acoustic boundary element analysis, acquiring a curve of the sound pressure level of an acoustic field point along with the frequency change, taking the maximum value of the sound pressure level as an abnormal sound degree evaluation standard, comparing the evaluation standard with an abnormal sound threshold value, and predicting whether the abnormal sound problem exists in the liquid resistance suspension.

2. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film according to claim 1, wherein in the step (2), in the dynamic simulation model, the runner plate is fixed, and the surface of the decoupling film applies pressure as a model input.

3. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film according to claim 1, wherein in the step (2), when the liquid resistance suspension of the floating decoupling film is adopted, the initial position of the decoupling film in the dynamic simulation model is in the middle position of the runner liquid chamber, when the liquid resistance suspension of the semi-floating decoupling film is adopted, the total thickness of the decoupling film is larger than the height of the runner air chamber, and the assembled decoupling film is in a compressed state.

4. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film according to claim 1, wherein the step (2) comprises the following substeps:

extracting a decoupling film-runner plate assembly model;

importing the decoupling film-runner plate assembly model into finite element pretreatment software for grid division;

importing the decoupling film-runner plate assembly model subjected to meshing into finite element analysis software, respectively setting material attributes of the decoupling film and the runner plate, applying model constraint conditions and loads, fixing the lower surface of the runner plate, applying pressure to the surface of the decoupling film, and carrying out simulation analysis on the surface vibration acceleration conditions of the decoupling film and the runner plate at the moment of plate collision of the decoupling film and the runner plate.

5. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film as claimed in claim 4, wherein the finite element preprocessing software adopts Hypermesh software, and the finite element analysis software adopts Abaqus.

6. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film as claimed in claim 1, wherein in the step (3), the time domain response of the vibration acceleration of the surface of the flow channel plate is calculated as the excitation of the acoustic simulation.

7. The simulation prediction method for the impact noise of the liquid resistance suspension decoupling film according to claim 1, wherein the decoupling film-flow channel plate acoustic boundary element simulation model in the step (4) selects the surface of the flow channel plate as a sound source surface.

8. The simulation prediction method for impact noise of the liquid resistance suspension decoupling membrane as claimed in claim 1, wherein the vibration acceleration information in the step (5) is subjected to Fourier transform and converted into a frequency domain signal, and then the frequency domain signal is used as an acoustic simulation excitation input.

9. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film according to claim 1, wherein in the step (5), the sound pressure calculation formula of the acoustic field point is

p＝{A _TV (ω)} ^T {a _n (ω)}

In the formula, p is the sound pressure of an acoustic field point; a. The _TV Acoustic transmission vectors of the structure surface nodes to the acoustic field points; a is _n The acceleration is the normal vibration acceleration of the surface of the structure; ω is angular velocity and T is transpose.

10. The simulation prediction method for impact noise of the liquid resistance suspension decoupling film according to any one of claims 1-9, characterized by further comprising the step (7) after the step (6): and (4) if the abnormal sound problem exists, optimizing the decoupling film-runner plate structure, and repeating the steps (1) to (6) until the sound pressure signal meets the requirement, wherein the three parameters of the thickness of the decoupling film, the height of the noise reduction rib and the gap between the decoupling film and the runner plate are optimized.

Images