A simulation and prediction method for impact noise of a hydro-elastic suspension decoupling membrane-flow channel plate

Abstract

The application discloses a simulation and prediction method for impact noise of a hydro-elastic mount decoupling film, which comprises the following steps: obtaining a three-dimensional structure model of a target hydro-elastic mount; establishing a dynamic simulation model of the decoupling film-flow channel plate, performing dynamic simulation, simulating the collision process of the decoupling film and the flow channel plate, and calculating the vibration response of the flow channel plate; based on the dynamic simulation model, establishing an acoustic boundary element simulation model of the decoupling film-flow channel plate; according to the vibration response, performing collision impact noise source processing and radiation noise calculation on the flow channel plate to obtain noise spectrum simulation results; and predicting the degree of the hydro-elastic mount impact noise and whether there is an abnormal noise problem according to the noise analysis results. The application predicts whether the hydro-elastic mount has an abnormal noise problem based on acoustic simulation, effectively reduces the number of experiments, and provides a reference for hydro-elastic mount structure design; the simplified decoupling film-flow channel plate model is used, the calculation time is greatly shortened under the premise of ensuring simulation accuracy, and the structure is optimized through batch simulation.

Description

Technical Field

[0001] This invention relates to the field of noise analysis of hydraulic suspension mounts in automotive powertrains, and particularly to a simulation prediction method for impact noise of hydraulic suspension decoupling membrane-flow channel plate. Background Technology

[0002] As an engine vibration damping component, the hydraulic resistance mount possesses relatively ideal dynamic characteristics. Its internal inertial channel-decoupling membrane structure enables it to exhibit high damping at low frequencies and low stiffness at high frequencies. However, the complex structure also introduces noise issues. Hydraulic resistance mount noise is categorized into impact noise and cavitation noise. Cavitation noise occurs when the liquid in the mount vaporizes at low pressure and then bursts under pressure at high pressure, generating a shock wave. Known effective methods to avoid cavitation noise include adding a pressure relief valve and installing a bypass channel. Impact noise is generated when the decoupling membrane floats up and down, impacting the flow channel plate during operation. This noise is more noticeable under low-frequency, high-amplitude conditions; in real-world driving, this manifests as a noticeable rattling sound felt in the cabin when the car travels at low speed over rough roads. The inherent structure of the hydraulic resistance mount dictates that impact processes inevitably occur during operation. Therefore, studying the generation mechanism and prediction methods of impact noise is crucial for resolving this noise problem.

[0003] The noise generated by the collision between the decoupling membrane and the flow channel plate can be divided into two stages: acceleration noise and self-ringing noise. Acceleration noise refers to the large vibration acceleration caused by the instantaneous impact force of the collision on the surface of the object, and the noise generated by the surrounding medium due to pressure fluctuations. Self-ringing noise corresponds to the free decay vibration stage, where the acceleration of the object surface gradually decays and the noise radiation also gradually decreases.

[0004] When studying the abnormal noise problem of liquid resistance suspension through experiments, the testing methods include: 1) directly measuring the sound pressure signal using a microphone, and using the peak sound pressure level to evaluate the noise level; 2) measuring the support reaction force signal at the fixed end of the liquid resistance suspension using a force sensor, and removing the excitation force on the liquid resistance suspension through high-pass filtering to obtain the force signal generated by the collision and impact of the decoupling membrane-flow channel plate, taking the peak value of the signal as the noise evaluation standard. The experimental methods require physical liquid resistance suspension components, making it impossible to predict the noise situation of the liquid resistance suspension in the early design stage, and also hindering the optimization of the component structure. However, the experimental tests can be used to verify the accuracy of the simulation methods.

[0005] In the existing technology, the simulation prediction methods for abnormal noise of liquid resistance suspension include: 1) performing fluid-structure interaction finite element simulation on the liquid resistance suspension to solve the change of the decoupling membrane impact force over time, and using the peak impact force as the basis for judging abnormal noise. This method requires modeling the entire liquid resistance suspension and considering the fluid-structure interaction effect, which makes the model more complex; 2) simulating the relationship curve between the contact force and equivalent displacement between the decoupling membrane and the flow channel plate, and using the maximum contact stiffness to evaluate the impact noise of the decoupling membrane. If the maximum contact stiffness exceeds 300 N / mm, it is judged that there is an abnormal noise problem. However, this standard is not applicable to liquid resistance suspensions with different structures, and this method also does not analyze the abnormal noise problem from an acoustic perspective. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention proposes a simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane. The method analyzes impact noise from an acoustic perspective and can quickly and accurately analyze and predict abnormal noise in liquid resistance suspensions.

[0007] To achieve the objective of this invention, the present invention provides a simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane, comprising the following steps:

[0008] ① Obtain the three-dimensional structural model of the target liquid resistance suspension;

[0009] ② Extract the decoupling membrane-flow channel plate assembly model from the target liquid resistance suspension three-dimensional structural model, draw a mesh on the assembly model, assign material properties, add constraints and loads, establish a dynamic simulation model, and perform transient finite element simulation;

[0010] ③ Calculate the collision impact response of the decoupled membrane-flow channel plate and obtain the vibration acceleration information of the flow channel plate surface;

[0011] ④ Based on the dynamic simulation model, define the acoustic boundary conditions and sound source surface, set the acoustic field points to be analyzed, and establish a decoupled membrane-flow channel plate acoustic boundary element simulation model.

[0012] ⑤ Load the vibration acceleration information as a sound source into the acoustic boundary element simulation model of the decoupled membrane-flow channel plate, and calculate the sound pressure level distribution of external field points in the decoupled membrane-flow channel plate model;

[0013] ⑥ Perform acoustic boundary element analysis to obtain the sound pressure level curve of the acoustic field point as a function of frequency. Use the maximum sound pressure level as the evaluation standard for the degree of abnormal noise and compare it with the abnormal noise threshold to predict whether there is an abnormal noise problem in the liquid resistance suspension.

[0014] Furthermore, in step ②, in the dynamic simulation model, the flow channel plate is fixed, and pressure is applied to the surface of the decoupling membrane as the model input.

[0015] Furthermore, in step ②, when the decoupling membrane is a floating liquid resistance suspension, the initial position of the decoupling membrane in the dynamic simulation model is in the middle of the liquid chamber of the flow channel. When the decoupling membrane is a semi-floating liquid resistance suspension, the total thickness of the decoupling membrane is greater than the height of the gas chamber of the flow channel, and the assembled decoupling membrane is in a compressed state.

[0016] Furthermore, step ② includes the following sub-steps:

[0017] Extract the decoupling membrane-flow channel plate assembly model;

[0018] Import the decoupling membrane-flow channel plate assembly model into the finite element preprocessing software for mesh generation;

[0019] The decoupling membrane-flow channel plate assembly model after mesh generation is imported into the finite element analysis software. Then, the material properties of the decoupling membrane and the flow channel plate are set respectively, and model constraints and loads are applied. The lower surface of the flow channel plate is fixed, and pressure is applied to the surface of the decoupling membrane. The surface vibration acceleration of the decoupling membrane and the flow channel plate at the moment of collision is simulated and analyzed.

[0020] Furthermore, the finite element preprocessing software used is HyperMesh, and the finite element analysis software used is Abaqus.

[0021] Furthermore, in step ③, the time-domain response of the vibration acceleration on the surface of the flow channel plate is calculated as the excitation for the acoustic simulation.

[0022] Furthermore, in step ④, the acoustic boundary element simulation model of the decoupled membrane-flow channel plate selects the surface of the flow channel plate as the sound source surface.

[0023] Furthermore, the vibration acceleration information in step ⑤ is transformed into a frequency domain signal by Fourier transform and then used as the excitation input for acoustic simulation.

[0024] Furthermore, in step ⑤, the formula for calculating the sound pressure at the acoustic field point is:

[0025] p = {A TV (ω)} T {a n (ω)}

[0026] In the formula, p is the sound pressure at the acoustic field point; A TV a is the acoustic transfer vector from a node on the structural surface to a point in the acoustic field; n ω is the normal vibration acceleration of the structural surface; ω is the angular velocity; and T is the transpose.

[0027] Furthermore, after step ⑥, step ⑦ is also included: if the analysis determines that there is an abnormal noise problem, the decoupling membrane-flow channel plate structure is optimized, and steps ① to ⑥ are repeated until the sound pressure signal meets the requirements. The optimization is carried out based on three parameters: 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.

[0028] The abnormal noise threshold in step ⑥ is obtained through simulation analysis and experimental testing of different types of liquid resistance suspensions and decoupling membrane-flow channel plates with different structures. This abnormal noise threshold is between the "maximum simulated sound pressure without abnormal noise" and the "minimum simulated sound pressure with abnormal noise". The range can be continuously narrowed by increasing the data to make the value more accurate.

[0029] The structural optimization in step ⑦ involves optimizing the decoupling membrane structure. Common noise reduction methods include adding noise-reducing ribs and using semi-floating decoupling membrane structures. Structural optimization generally considers three design parameters of the decoupling membrane: decoupling membrane thickness, noise-reducing rib height, and the gap between the decoupling membrane and the flow channel plate. The optimal values ​​of these parameters can be analyzed from these three aspects to obtain a better noise reduction effect. The smaller the gap between the decoupling membrane and the flow channel plate, the lower the noise. However, the increase in fluid resistance suspension stiffness caused by the reduction in gap should also be considered. The noise is generally lower when the decoupling membrane thickness and noise-reducing rib height are designed within a specific range.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] 1) This invention analyzes the impact noise problem of the liquid resistance suspension decoupling membrane based on the collision acoustics theory. The simulation method can predict whether there is abnormal noise in the liquid resistance suspension, effectively reducing the number of experiments and providing a reference for the design of liquid resistance suspension structure.

[0032] 2) The liquid resistance suspension structure is relatively complex, but the impacted components are the decoupling membrane and the flow channel plate. Therefore, this invention can analyze only the decoupling membrane-flow channel plate model, which can significantly shorten the calculation time while accurately predicting the impact noise of the liquid resistance suspension, and facilitate the optimization of the structure through batch simulation.

[0033] 3) This invention can predict and analyze different types of liquid resistance suspensions, and is applicable to both floating and semi-floating decoupling membranes. The proposed abnormal noise threshold can be used as a unified standard for different liquid resistance suspensions. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0035] Figure 1 This is a flowchart illustrating the steps of a simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane-flow channel plate provided in an embodiment of the present invention.

[0036] Figure 2 This is a finite element model diagram of the decoupling membrane-flow channel plate in an embodiment of the present invention.

[0037] Figure 3 This is a cloud map of the acoustic simulation field sound pressure level in an embodiment of the present invention.

[0038] Figure 4 This is a simulated acoustic pressure spectrum of the liquid resistance suspension (1) in the embodiment of the present invention when using different decoupling membrane structures.

[0039] Figure 5 This is a simulated acoustic pressure spectrum of the liquid resistance suspension (2) in this embodiment of the invention when using different decoupling membrane structures. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figure 1 As shown, the present invention provides a simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane, comprising the following steps:

[0042] Step 1: Obtain the three-dimensional structural model of the target liquid resistance suspension.

[0043] 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 mesh on the assembly model, assign material properties, add constraints and loads, establish a dynamic simulation model, and perform transient finite element simulation.

[0044] In some embodiments of the present invention, the liquid resistance suspension has upper and lower flow channel plates, and the lower flow channel plate and the liquid resistance suspension base are designed as a whole. To simplify the model, only the part of the lower flow channel plate that may come into contact with the decoupling membrane is taken. The decoupling membrane-flow channel plate assembly model is imported into HyperMesh software, and the decoupling membrane is set to a hexahedral mesh, the flow channel plate is set to a tetrahedral mesh, and the mesh size is 1 mm (other values ​​can be set in other embodiments). The decoupling membrane-flow channel plate assembly model is then meshed.

[0045] The meshed decoupling membrane-flow channel plate assembly model was imported into the finite element analysis software. Then, the material properties of the decoupling membrane and the flow channel plate were set, and model constraints and loads were applied. The lower surface of the flow channel plate was fixed, and pressure was applied to the surface of the decoupling membrane. Since there was an initial gap between the decoupling membrane and the flow channel plate, they collided under excitation. The surface vibration acceleration of the decoupling membrane and the flow channel plate at the moment of collision was simulated and analyzed.

[0046] In some embodiments of the present invention, the flow channel plate material is defined as metallic aluminum with a density of 2700 kg / m³. 3 The Young's modulus is 72500 MPa, and the Poisson's ratio is 0.33; the decoupling membrane material is rubber with a density of 1100 kg / m³. 3 The Mooney-Rivlin hyperelastic constitutive model is used, with the parameter C. 10 =0.2897MPa, C 01 =0.0599MPa. The impact process between the decoupling membrane and the flow channel plate is simulated. Six degrees of freedom in the lower surface of the flow channel plate are constrained, and pressure is applied to the surface of the decoupling membrane as an excitation for transient finite element simulation. The specific values ​​above are just one example; other values ​​can be used in other embodiments.

[0047] In some embodiments of the present invention, the finite element analysis software used is Abaqus.

[0048] 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 is understood that in other embodiments, the applied pressure may be set to other values.

[0049] In some embodiments of the present invention, the simulation duration is set to 10ms in this step. Of course, it is understood that in other embodiments, the simulation duration can be set to other values.

[0050] In some embodiments of the present invention, the dynamic simulation model is as follows: 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 resistance suspension, 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-flow channel plate model, the decoupling membrane needs to be pre-compressed for simulation processing.

[0051] Step 3: Submit the analysis task in the finite element analysis software, calculate the collision impact response of the decoupled membrane-flow channel plate, and obtain the vibration acceleration information of the flow channel plate surface.

[0052] Step 4: Based on the dynamic simulation model, define the acoustic boundary conditions and sound source surface, set the acoustic field points to be analyzed, and establish the decoupled membrane-flow channel plate acoustic boundary element simulation model.

[0053] In some embodiments of the present invention, the finite element analysis result file obtained in step 3 is imported into LMS Virtual.Lab. Based on the dynamic simulation model, the outer surface of the flow channel plate is set as the sound source surface, the propagation medium is defined as air, and the point on the Y-axis 1m away from the center of the dynamic simulation model is selected as the acoustic field point to establish the decoupled membrane-flow channel plate acoustic boundary element simulation model.

[0054] Step 5: Load the vibration acceleration information as a sound source into the acoustic boundary element simulation model of the decoupling membrane-flow channel plate, and calculate the sound pressure level distribution of external field points in the decoupling membrane-flow channel plate model.

[0055] In some embodiments of the present invention, the vibration acceleration time-domain signal obtained from dynamic simulation is subjected to Fourier transform and loaded as an excitation source into the acoustic boundary element simulation model of decoupled membrane-flow channel plate. The frequency range for solving is set to 40Hz to 2000Hz with an interval of 40Hz, and the sound pressure level distribution of the external field is simulated and analyzed.

[0056] Wherein, according to the formula p={A TV (ω)} T {a n (ω)} calculates the sound pressure at an acoustic field point, where: p is the sound pressure at the acoustic field point; A TV The Acoustic Transfer Vector (ATV) is the sound transfer vector from a structural surface node to an acoustic field point. It 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; it is an inherent property of the system. n The normal vibration acceleration of the structural surface is represented by the superscript T, which indicates that the formula is solved in the frequency domain. However, the acceleration signal obtained from the dynamic simulation is a time domain signal, so it should be converted into a frequency domain signal by Fourier transform before input.

[0057] Step 6: Simulate the sound pressure level curve of the field point as a function of frequency, and use the maximum sound pressure level, i.e. the peak sound pressure level, as the evaluation standard for abnormal noise. Compare it with the abnormal noise threshold to predict the impact noise of the liquid resistance suspension.

[0058] The abnormal noise threshold is determined by simulation and experimentation on decoupled membrane-flow channel plates with various structures. In some embodiments of the present invention, the abnormal noise threshold is set at 57 dB. If the peak sound pressure level obtained from the simulation exceeds the abnormal noise threshold, the liquid resistance suspension is determined to have an abnormal noise problem; otherwise, the noise of the liquid resistance suspension is considered to be within an acceptable range. In other embodiments, the abnormal noise threshold may also be a numerical value.

[0059] This invention provides a simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane. The method can determine the degree of abnormal noise from the liquid resistance suspension through simulation analysis. Furthermore, this method uses a simplified decoupling membrane-flow channel plate model, making it suitable for batch simulations of different structures and enabling optimization of the decoupling membrane-flow channel plate structure. It can also perform predictive analysis on different types of liquid resistance suspensions and is applicable to both floating and semi-floating decoupling membrane structures.

[0060] The above description of the disclosed embodiments enables those 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 invention is not to 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

1. A simulation prediction method for impact noise of a liquid resistance suspended decoupling diaphragm, characterized in that, Includes the following steps: ① Obtain the three-dimensional structural model of the target liquid resistance suspension; ② Extract the decoupling membrane-flow channel plate assembly model from the target liquid resistance suspension three-dimensional structural model, draw a mesh on the assembly model, assign material properties, add constraints and loads, establish a dynamic simulation model, and perform transient finite element simulation; ③ Calculate the collision impact response of the decoupled membrane-flow channel plate and obtain the vibration acceleration information of the flow channel plate surface; ④ Based on the dynamic simulation model, define the acoustic boundary conditions and sound source surface, set the acoustic field points to be analyzed, and establish a decoupled membrane-flow channel plate acoustic boundary element simulation model. ⑤ Load the vibration acceleration information as a sound source into the acoustic boundary element simulation model of the decoupled membrane-flow channel plate, and calculate the sound pressure level distribution of external field points in the decoupled membrane-flow channel plate model; ⑥ Perform acoustic boundary element analysis to obtain the sound pressure level curve of the acoustic field point as a function of frequency. Use the maximum sound pressure level as the evaluation standard for the degree of abnormal noise and compare it with the abnormal noise threshold to predict whether there is an abnormal noise problem in the liquid resistance suspension. In step ②, in the dynamic simulation model, the flow channel plate is fixed, and pressure is applied to the surface of the decoupling membrane as the model input; In step ②, when the decoupling membrane is suspended by liquid resistance, the initial position of the decoupling membrane in the dynamic simulation model is in the middle of the liquid chamber of the flow channel. When the decoupling membrane is suspended by liquid resistance, the total thickness of the decoupling membrane is greater than the height of the gas chamber of the flow channel. The assembled decoupling membrane is in a compressed state. Step ② includes the following sub-steps: Extract the decoupling membrane-flow channel plate assembly model; Import the decoupling membrane-flow channel plate assembly model into the finite element preprocessing software for mesh generation; The decoupling membrane-flow channel plate assembly model after mesh generation is imported into the finite element analysis software. Then, the material properties of the decoupling membrane and the flow channel plate are set respectively, the model constraints and loads are applied, the lower surface of the flow channel plate is fixed, and pressure is applied to the surface of the decoupling membrane. The surface vibration acceleration of the decoupling membrane and the flow channel plate at the moment of collision is simulated and analyzed. In step ⑤, the formula for calculating the sound pressure at the acoustic field point is: In the formula, The sound pressure at the acoustic field point; is the acoustic transmission vector from the structural surface node to the acoustic field point; The normal vibration acceleration of the structural surface; Let ω be the angular velocity and T be the transpose.

2. The simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane according to claim 1, characterized in that, The finite element preprocessing software used is HyperMesh, and the finite element analysis software used is Abaqus.

3. The simulation prediction method for impact noise of a liquid resistance suspended decoupling membrane according to claim 1, characterized in that, In step ③, the time-domain response of the vibration acceleration on the surface of the flow channel plate is calculated as the excitation for the acoustic simulation.

4. The simulation prediction method for impact noise of a liquid resistance suspended decoupling membrane according to claim 1, characterized in that, In step ④, the acoustic boundary element simulation model of the decoupling membrane-flow channel plate selects the surface of the flow channel plate as the sound source surface.

5. The simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane according to claim 1, characterized in that, The vibration acceleration information in step ⑤ is converted into a frequency domain signal by Fourier transform and then used as the excitation input for acoustic simulation.

6. A simulation prediction method for impact noise of a liquid resistance suspension decoupling membrane according to any one of claims 1-5, characterized in that, After step ⑥, step ⑦ is also included: if the analysis determines that there is an abnormal noise problem, the decoupling membrane-flow channel plate structure is optimized, and steps ① to ⑥ are repeated until the sound pressure signal meets the requirements. The optimization is carried out based on three parameters: 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.

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